PH-4107_5102_Lecture Notes 8/29/2013

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "PH-4107_5102_Lecture Notes 8/29/2013"

Transcription

1 NMR SPECTROCOPY NMR - Classification CLASSIFICATION C-13 NMR -THEORY PMR -THEORY C-13 NMR INSTRUMENTATION PMR INSTRUMENTATION Low Field NMR High Field NMR Small Molecule NMR Macromolecular / Protein NMR FEATURES OF C-13 NMR SPECTRA FEATURES OF PMR SPECTRA Continuous Wave Mode NMR Pulsed FTNMR INTERPRETATION OF C-13 NMR SUMMARY INTERPRETATION OF PMR SUMMARY Solution phase NMR Solid State NMR NMR Screening (HTS) NMR Imaging (MRI) 1 2 NMR - classification 1D NMR 2D / 3D NMR Homonuclear NMR Heteronuclear NMR HSQC HMQC NMR Spectroscopy - Introduction NMR Spectroscopy is the most powerful tool in determining the structure of organic compounds. NMR requires only a small amount (mg or less) of sample and the sample can be recovered. Can be used in conjunction with other means of identification, but often this is the only tool necessary and is an indispensable one. A wide variety of nuclei can be studied by NMR: 1 H, 13 C, 15 N, 19 F, and 31 P. 1 H and 13 C are the most commonly studied nuclei. H-1, C-13, N-15 NMR O-17, F-19 NMR INEPT INADEQUATE 3 4 Fig 1. Fig 2. All nuclei carry charge due to the positively charged protons located there. Sometimes this charge spins and generates a magnetic dipole alongtheaxisofspin. In the absence of Ho, the magnetic moments are random. When the field is applied, they tend to align with(α spin-lower energy) or against (β spin-higher energy) the external field(fig 1). 5 Based on Boltzmann distribution phenomena, the population of lower energy level will be slightly more than the higher energy level nuclei. When a proton in the α state (low energy, slight excess) is irradiated with the proper frequency, ν, it can go to the higher energy β state or vice versa. At that frequency, they are in resonance. 6 A S Raja, Dept of Pharma, IIT (BHU). 1

2 The frequency of radiation (Rf) required is determined by the difference in the energy level of two transition states. Calculation of transition energy Magnetic moment of nucleus µ = γ I h / 2π γ -Gyromagnetic ratio I spin of nucleus h- Plank s constant The difference in energy between two states E = γ h B 0 / 2π B 0 Strength at nucleus i.e., If magnetic field strength B 0 and gyromagnetic ratio γ of nuclei is large then so is E Fig 3 Larmor frequency A nuclei with ½ spin, placed in a magnetic field, if align with the magnetic field, takes the lower energy level (alpha state, see Fig 4) start spinning on its axis. The axis of rotation will precess around the applied magnetic field. The frequency of precession is termed the Larmor frequency Fig 4. Spinning nucleus 7 8 Excitation Process - Absorption of Rf When the nucleus absorbs radiation (Rf) then the angle of precession (θ) changes and the radiation flips the magnetic moment so that it opposes the applied field thus reaching the higher energy state(beta state). Spin saturation Only a small proportion of nuclei (slight excess) in the lower energy state can absorb radiation and reaches the excited state. Such excitation will bring a situation at which the nuclei of lower and higher energy levels will be equal (spin system is saturated) and no more absorption of Rf occurs. Relaxation Process How do the nuclei of higher energy return to the lower state? Since, re-emission of radiation is negligible at radio-frequencies, relaxation occurs only through non-radiative processes. There are two ways by which the excited nuclei can undergo relaxation process Spin-lattice longitudinal relaxation Theory of NMR Spectroscopy The sample in which the nuclei are held is called the lattice. Nuclei in the lattice are in vibrational and rotational motion thus creating a magnetic field, called lattice field. Some of the components of this lattice field will be equal in frequency and phase to the Larmor frequency of excited nuclei. These components can interact with the such excited nuclei and cause them to lose energy and return to their lower energy state (Such gain in lattice field increases the amount of vibration and motion, thus resulting in a tiny rise in temperature of sample) Greater vibrational & rotational frequencies greater the ability tointeractwithexcitednuclei fastertherateofrelaxationrate line-broadening of the spectrum occurs Spin-spin transverse relaxation This occurs due to the interaction of neighboring nuclei with identical processional frequencies but differing magnetic quantum states. A nucleus in low energy state will be excited, while the high energy nuclei relaxes to the lower energy state. There will be no net change in the populations of the energy states but the average lifetime of a nucleus in the excited state will decrease. This can cause line broadening in the spectrum NMR Spectrum It is a plot of the intensity of NMR signals versus the magnetic field[frequency in hertz or chemical shift derived from frequency (Hz)/ spectrometer frequency (MHz)] Resonance of Protons If all protons were equal, then NMR would be useless, but they are not all equal. That is, the frequency Rf needed to achieve resonance varies depending on the proton s environment. Magnetic shielding in protons When the electrons surrounding a proton encounter H 0, an induced field is set up oppositetoh 0. H effective = H external H shielding Fig 5. A typical proton NMR Spectrum A S Raja, Dept of Pharma, IIT (BHU). 2

3 Shielding and Chemical Shift The variations in shielding of the nucleus by the electrons result in variations of the signal locations- called chemical shifts. Chemical shift - the difference between the resonance frequency of the proton being observed and that of tetramethylsilane (TMS) (CH 3 ) 4 Si. This is reported in ppm and denoted by the symbol delta, δ. NMR Instrumentation TMS Important features of Proton NMR Spectra Number of signals Position of signals(chemical Shift) Relative intensity of signals(integration) Splitting of signals(coupling) 1. Number of Signals Protons within a compound experience different magnetic environments, which give a separate signal in the NMR spectrum. No of types of protons = No of NMR signals Fig 6. PMR Spectra of some compounds showing no. of signals with integral trace Position of signals (chemical shift) The position on the horizontal frequency scale at which the equivalent proton signals occur is called a chemical shift(measured in ppm). Factors affecting the position of signals (Chemical shift) A. Magnetic anisotropy B. Electronegativity C. Hybridization D. Hydrogen bonding A. Magnetic anisotropy Under an applied magnetic field, circulating electrons in the electron cloud produce a small opposing magnetic field, ultimately decreasing the effective magnetic field felt by the proton, shifting the signal to the right (or upfield). This effect, in which the electron cloud shields the proton from the applied magnetic field is called local diamagnetic shielding. A. Magnetic anisotropy effects Contd Example 1. Aromatic rings Thepielectronsinanaromaticringareinduced to circulate around the ring in response to an applied magnetic field. This "ring current" generates a local magnetic field which opposes the applied magnetic field. However, on the periphery of the ring, the flux lines are in the direction of the applied magnetic field. Consequently, protons attached to the aromatic ring"feel" a larger magnetic field than protons elsewhere in the molecule. Therefore, aromatic ring protons will resonate at higher frequency and exhibit a downfield shift (7-8 ppm) A S Raja, Dept of Pharma, IIT (BHU). 3

4 A. Magnetic anisotropy effects Contd. B. Electronegativity effects Example 2. Acetylene rings The pi electrons in a triple bond circulate around the bond axis to produce a magnetic field directly opposing the applied magnetic field. The acetylenic hydrogen is shielded by this induced field, and will therefore resonate at lower frequency (2-3pmm). Electronegative elements directly attached to a carbon atom bearing hydrogens(protons) pull electron density away from the protons. H s that are attached to more electronegative atoms experience higher chemical shifts. Electronegative atoms also remove electrons from the electron cloud, which decreases their density and results in less shielding; hence electronegative atoms are said to deshield the proton and cause it to have a higher chemical shift, moving it to the left(or downfield). The magnitude of the deshielding effect, however, rapidly decreases as the distance between the proton and electronegative atom increases B. Electronegativity effects on proton chemical shifts - Contd. C. Hybridization effects sp 3 Hydrogens Hydrogens attached to sp 3 hybridized carbon atoms resonate between0-2ppm. Figure 6. Electronegativity effects for fluoromethane(red-high electron density, blue- low electron density) CH 3 X CH 3 H CH 3 I CH 3 Br CH 3 Cl CH 3 F Element X H I Br Cl F Electronegativityof X Chemical Shift (Delta) sp Hydrogens Acetylenic hydrogens resonate between 2-3 ppm due to the anistropy of the carbon-carbon triple bond C. Hybridization effects sp 2 Hydrogens Hydrogens attached to sp 2 hybridized carbon atoms resonate farther downfield than for normal aliphatic protons. Vinylic Hydrogens- Hydrogens attached to carbon-carbon double bonds resonate between ppm. The sp 2 hybridized carbon atom of the double bond has increased s-character, and is therefore more electronegative than an sp 3 hybridized carbon atom. AromaticHydrogens-Theyresonatebetween7-8ppm. Aldehyde Hydrogens - Aldehyde protons resonate between 9-10 ppm. This further downfield shift is due to the additional effect of the electron withdrawing oxygen atom nearby. D. Hydrogen Bonding Effects Hydrogen bonding causes a further deshielding of protons, and a further downfield shift for these proton resonances. Hydrogen bonding effects are concentration and temperature dependent, and this results in a wide range of possible resonance frequencies for these protons. In general, protons attached to oxygen and nitrogen resonatebetween0.5-5ppm Examples: Amines (R-NH2) Alcohols(R-OH) A S Raja, Dept of Pharma, IIT (BHU). 4

5 3. Relative intensity of signals(integration) The area under the signals(integration) corresponds to the number of protons responsible for that signal. Therefore, the relative intensities of the signal are proportional to the relative number of proton equivalents. It is important to remember that integration only provides ratios of protons, not the absolute number. For convenience in calculating the relative signal strengths, the smallest integration is set to 1 and the other values are converted accordingly. Integrals appear as lines on the spectra above the signals, in which their heights correspond to the integration ratios. In this spectra, the OH:H ratio is correctlydetermined tobeina3:1. Fig 7. Spectra of methanol showing the integral trace and the ratio of hydrogen Splitting of signals(spin-spin coupling) NMR signals are not usually single triangles, but a complex pattern of split triangles labelled as doublets (2 peaks), triplets (3 peaks), quartets(4 peaks), etc. The distance between the split peaks are called coupling constants, denoted by J. The interaction between nearby protons produce different spin flip energies (E) as they can orient themselves in a pattern of parallel or anti-parallel to the applied magnetic force. This phenomenon, where the spin of the nucleus of one proton is close enough to affect the spin of another, is called spin-spin coupling. Rules of spin-spin coupling First order and non-first order(non-equivalent) coupling Example of non-first order or complex splitting Proton Spin-spin coupling Rules Splitting is always reciprocated between the protons if H a splits H b, thenh b must split H a andprovides information on the neighbours ofa proton within the molecule. N+1 Rule: For a proton with n neighbours, its signal will be split into n+1 lines. Three rules/restrictions for proton coupling 1. Nuclei with the same chemical shift (isochronous protons) do not couple with each other: the protons must be nonequivalent in order to couple. 2. Hydrogens bonded to a nitrogen or oxygen usually do not couple with other protons and appear as singlets on the NMR spectra. 3. Vicinal protons (protons separated by 3 bonds) can couple with each other. Protons that are more than 3 bonds away cannot because the signal they feel from their neighbor is too small to affect their spin. Fig 8. Spin-spin splitting pattern on protons 27 There is also geminal coupling coupling through 2 bonds and allylic coupling coupling through 4 bonds, if one is a pi bond. Pi bonds do not follow the 3 bond rule because the electron density around a pi bond is higher then in a single bond; hence, pi bonds can be counted as a free spacer. All hydrogens on the benzene ring couple with each other and the ring itself can be counted as a free spacer; however, H s on the benzene ring only couple with each other and not with H s attached to other atoms even if they are within the 3 bond max limit ( coupling club ) First order and non-first order coupling First order splitting produces normal splitting patterns that have equal J values. Non-first order splitting occurs when a nucleus spin-couples with 2 or more sets of nearby nuclei that have different J values. Complex Splitting Patterns: Non-equivalent coupling Thus far, we have concentrated on spin-spin coupling with only one other nonequivalent set of H atoms More complex splittings arise when a set of H atoms couples to more than one set H atoms A tree diagram shows that when H b is adjacent to nonequivalent H a on one side and H c on the other, the resulting coupling gives rise to a doublet of doublets (J ab > J bc ) Fig 10. First order and non-first order coupling (Splitting) A S Raja, Dept of Pharma, IIT (BHU). 5

6 Complex Splitting Patterns: Non-equivalent coupling if H c is a set of two equivalent H, then the observed splitting is a doublet of triplets Example: Vinyl acetate - Non-equivalent coupling Since H c and H b are not equivalent to each other, we cannot merely add them together and use the n + 1 rule. When two sets of adjacent protons are different from each other and couple to a common set of protons with different J, (n protons on one adjacent carbon and m protons on the other), the number of peaks in an NMR signal = (n + 1)(m + 1) Proton NMR Interpretation 1 H NMR Spin-Spin Splitting Example: Vinyl acetate Splitting diagrams for the alkenyl protons in vinyl acetate are shown below. Note that each pattern is different in appearance because the magnitude of the coupling constants is different. 33 Fig. 11. Proton NMR correlation chart 34 Proton NMR Interpretation Chart NMR Interpretation - Proton NMR Problems 1.ProtonNMRofalkenes Geminal,cis&transprotons Protons on carbon-carbon double bonds often give characteristic splitting patterns. A disubstituted double bond can have two geminal protons, two cis protons, or two trans protons. When these protons are different, each proton splits the NMR signal of theothersothateachproton appearsasadoublet. The magnitude of the coupling constant J for these doublets depends on the arrangement of hydrogen atoms. Fig. 12. Proton NMR correlation chart A S Raja, Dept of Pharma, IIT (BHU). 6

7 Typical Proton Coupling Constants for Alkenes NMR Interpretation Alkenylprotons NMR Interpretation Alkenyl protons 2 J geminal 0-5 Hz 3 J cis 6-15 Hz 3 J trans Hz 3 J 4-10 Hz 3 J 9-13 Hz 3 J 0-2 Hz 3 J 2-4 Hz 3 J 5-7 Hz 3 J 8-11 Hz cis and trans coupling NMR Interpretation - Proton NMR Problems 2. Proton NMR - OH Protons Under usual conditions,an OH protondoes not split the NMR signal of adjacent protons. Also, the signal of OH proton is not split by adjacent/neighboring protons. NMR Interpretation - Proton NMR Problems Proton NMR - OH Protons Contd Ethanol (CH 3 CH 2 OH) has three different types of protons, so there are three signals in its NMR spectrum. TheH a signalissplitbythetwoh b protonsintothreepeaks(atriplet). The H b signal is split only by the three H a protons into four peaks, a quartet.theadjacentohprotondoesnotsplitthesignalduetoh b. H c isasingletbecauseohprotonsarenotsplitbyadjacentprotons. Protons on electronegative atoms rapidly exchange between molecules in the presence of trace amounts of acid or base. Thus, the CH 2 group of ethanol never feels the presence of the OH proton, because the OH proton is rapidly moving from one molecule to another. This phenomenon usually occurs with NH and OH protons. Fig. x. 1D spectra of ethanol NMR Interpretation - Proton NMR Problems 3. Proton NMR - Cyclohexane Conformers Cyclohexane conformers interconvert by ring flipping. Because the ring flipping is very rapid at room temperature, an NMR spectrum records an average of all conformers that interconvert. Thus, even though each cyclohexane carbon has two different types of hydrogens one axial and one equatorial the two chair forms of cyclohexane rapidly interconvert them, and an NMR spectrum shows a single signal for the average environment that it sees. NMR Interpretation Phenyl protons 4. Proton NMR - Protons on benzene rings Benzene has six equivalent deshielded protons and exhibits a singlepeakinitsprotonnmrspectrumat7.27ppm. Mono-substituted benzenes contain five protons that are no longer structurally equivalent will appear as a singlet when the substituent bonded to the ringis an sp 3 hybridized carbon because of Magnetic Equivalence. That is they all have the same chemical shift. If the atom or group bonded to the ring is other than an sp 3 hybridized carbon, the NMR absorption region is more complex A S Raja, Dept of Pharma, IIT (BHU). 7

8 NMR Interpretation Phenyl protons NMR Interpretation Phenyl protons 1,4-Dichlorobenzene All H s are equivalent - singlet 1-Chloro-4-iodobenzene SingleH a splitsh b intoadoubletandh b splitsh a intoadoublet b a b a NMR Interpretation Phenyl protons 4-Methyl acetophenone Single H a splits H b into a doublet and H b splits H a into a doublet NMR Interpretation - Proton NMR Problems 5. Aldehydes Proton on carbonyl oxygen (R-CHO) Thechemicalshift ofthe aldehydic hydrogenis distinctive.it fallsintherange δ Nothing else appears in that range. b b a a 6. Acids Proton on acidic hydroxyl group (R-COOH) The acid proton falls roughly into the range δ However, it is often broadened, especially in concentrated solutions, and may not appear as a peak. The integration will still be there, though! Note: NMR is not the method of choice for identifying this functional group! 7. Ethers & Esters (R-CH 2 -O-R & R-CO-O-CH 2 -R) A distinctive feature in the 1 H-NMR spectra of ethers is the chemical shift, δ , of hydrogens on carbon attached to the ether oxygen. This also appears in esters NMR Problems -Interpretation of NMR Spectra of simple organic compounds Low resolution NMR spectra The number of peaks tells you the number of different environments the hydrogen atoms are in. The ratio of the areas under the peaks tells you the ratio of the numbers of hydrogen atoms in each of these environments. The chemical shifts give you important information about the sort of environment the hydrogen atoms are in. 47 NMR Problems -Interpretation of NMR Spectra of simple organic compounds High resolution NMR spectra In a high resolution spectrum, you find that many of what looked like single peaks in the low resolution spectrum are split into clusters of peaks. 1 peak a singlet 2 peaks in the cluster a doublet 3 peaks in the cluster a triplet 4 peaks in the cluster a quartet Note: You can get exactly the same information from a high resolution spectrum as from a low resolution one - you simply treat each cluster of peaks as if it were a single one in a low resolution spectrum. But in addition, the amount of splitting of the peaks gives you important extra information. A S Raja, Dept of Pharma, IIT (BHU). 8

9 Toluene tert- Butyl acetate Methyl propanoic acid 4-Chloroaniline Butanamine Butanal A S Raja, Dept of Pharma, IIT (BHU). 9

10 Problem Solving in Proton NMR Problem solving in proton NMR - Steps If the molecular formula is known, determine the elements of unsaturation = C - ((H+X-N)/2) + 1 C = number of carbons, H = No of hydrogens, X = No of of halogen atoms, N = No of nitrogen. First degree means that you have a ring or a double bond and second degree means you have a triple bond. Matching the integrations with protons in the formula give the numbers of proton represented by the individual peaks, as well as possible symmetry. Any broadened singlets might be due to -OH or NH protons. Signals downfield from 10 ppm might be acids. 55 Example 1: Propose a chemical structure of PMR spectra of the molecular formula C 4 H 8 O 2 Treating this as a low resolution spectrum to start with, there are three clusters of peaks and so three different environments for the hydrogens. The hydrogens in those three environments are in the ratio 2:3:3. Since there are 8 hydrogens altogether, this represents a CH 2 group and two CH 3 groups. 56 So what is the structure of the compound? Molecular formula C 4 H 8 O 2 Splitting pattern? The CH 2 group at about 4.1 ppm is a quartet. That tells you that it is next to a carbon with three hydrogens attached - a CH 3 group. The CH 3 group at about 1.3 ppm is a triplet. That must be next to a CH 2 group. This combination of these two clusters of peaks - one a quartet and the other a triplet - is typical of an ethyl group, CH 3 CH 2. It is very common. Get to recognise it! Finally, the CH 3 group at about 2.0 ppm is a singlet. That means that the carbon next doesn't have any hydrogens attached Example 2: Propose a chemical structure consistent with the following high resolution proton NMR spectra and molecular formula Determine the elements of unsaturation. 4-(10/2)+1=0, Therefore the oxygens must be part of either an alcohol or an ether. The doublet at δ 1.1 represents 3H and must be a CH 3 next to a CH group. The peaks centered at δ1.6 integrating to 2H appear to be an uneven quartet, which signifies a CH 2 between two sets of nonequivalent protons. The broad 2H singlet at δ 3.3 has the earmark of OH protons, so apparently the compound is a diol A S Raja, Dept of Pharma, IIT (BHU). 10

11 Summary of H-1 NMR The 3H multiplet centered around δ 3.8 is very complex; while the splitting is hard to interpret, the chemical shift suggests that these 3 hydrogens are on carbons bonded to oxygen. High resolution PMR Provides information about protons and its environment PMR has a narrow chemical shift range (0-10ppm) and placing all kinds of protons in such narrow range yields a complex correlation chart with inherent ambiguity. Though the raw PMR spectra is complex, proper post spectral analysis (splitting pattern, coupling constant etc) would help to retrieve the maximum information about the proton environment. Finallythestructureofthecompoundis...? A S Raja, Dept of Pharma, IIT (BHU). 11

Proton Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy

Proton Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy Proton Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy Theory behind NMR: In the late 1940 s, physical chemists originally developed NMR spectroscopy to study different properties of atomic nuclei,

More information

By far the most important and useful technique to identify organic molecules. Often the only technique necessary.

By far the most important and useful technique to identify organic molecules. Often the only technique necessary. Chapter 13: NMR Spectroscopy 39 NMR Spectroscopy By far the most important and useful technique to identify organic molecules. Often the only technique necessary. NMR spectrum can be recorded for many

More information

Nuclear Magnetic Resonance Spectroscopy

Nuclear Magnetic Resonance Spectroscopy Nuclear Magnetic Resonance Spectroscopy Introduction NMR is the most powerful tool available for organic structure determination. It is used to study a wide variety of nuclei: 1 H 13 C 15 N 19 F 31 P 2

More information

PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY (H-NMR)

PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY (H-NMR) PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY (H-NMR) WHAT IS H-NMR SPECTROSCOPY? References: Bruice 14.1, 14.2 Introduction NMR or nuclear magnetic resonance spectroscopy is a technique used to determine

More information

Used to determine relative location of atoms within a molecule Most helpful spectroscopic technique in organic chemistry Related to MRI in medicine

Used to determine relative location of atoms within a molecule Most helpful spectroscopic technique in organic chemistry Related to MRI in medicine Structure Determination: Nuclear Magnetic Resonance CHEM 241 UNIT 5C 1 The Use of NMR Spectroscopy Used to determine relative location of atoms within a molecule Most helpful spectroscopic technique in

More information

Proton Nuclear Magnetic Resonance Spectroscopy

Proton Nuclear Magnetic Resonance Spectroscopy Proton Nuclear Magnetic Resonance Spectroscopy Introduction: The NMR Spectrum serves as a great resource in determining the structure of an organic compound by revealing the hydrogen and carbon skeleton.

More information

Organic Chemistry Tenth Edition

Organic Chemistry Tenth Edition Organic Chemistry Tenth Edition T. W. Graham Solomons Craig B. Fryhle Welcome to CHM 22 Organic Chemisty II Chapters 2 (IR), 9, 3-20. Chapter 2 and Chapter 9 Spectroscopy (interaction of molecule with

More information

Chemical Shift (δ) 0 (by definition) 0.8-1.0 1.2-1.4 1.4-1.7 1.6-2.6 2.0-3.0 2.2-2.5 2.3-2.8 0.5-6.0 3.4-4.0 3.3-4.0 0.5-5.0

Chemical Shift (δ) 0 (by definition) 0.8-1.0 1.2-1.4 1.4-1.7 1.6-2.6 2.0-3.0 2.2-2.5 2.3-2.8 0.5-6.0 3.4-4.0 3.3-4.0 0.5-5.0 Chemical Shifts 1 H-NMR Type of Hydrogen (CH 3 ) 4 Si RCH 3 RCH 2 R R 3 CH R 2 C=CRCHR 2 RC CH ArCH 3 ArCH 2 R ROH RCH 2 OH RCH 2 OR R 2 NH O RCCH 3 O RCCH 2 R Chemical Shift (δ) 0 (by definition) 0.8-1.0

More information

Chapter 13 Nuclear Magnetic Resonance Spectroscopy

Chapter 13 Nuclear Magnetic Resonance Spectroscopy Organic Chemistry, 6 th Edition L. G. Wade, Jr. Chapter 13 Nuclear Magnetic Resonance Spectroscopy Jo Blackburn Richland College, Dallas, TX Dallas County Community College District 2006, Prentice Hall

More information

NMR Spectroscopy. Introduction

NMR Spectroscopy. Introduction Introduction NMR Spectroscopy Over the past fifty years nuclear magnetic resonance spectroscopy, commonly referred to as nmr, has become the most important technique for determining the structure of organic

More information

Shielding and Chemical Shift. Figure 14.3

Shielding and Chemical Shift. Figure 14.3 Shielding and Chemical Shift Figure 14.3 1 Summary of Shielding Figure 14.4 2 Shielding and Signal Position 3 Characteristic Chemical Shifts Protons in a given environment absorb in a predictable region

More information

Chapter 11 Structure Determination: Nuclear Magnetic Resonance Spectroscopy. Nuclear Magnetic Resonance Spectroscopy. 11.1 Nuclear Magnetic Resonance

Chapter 11 Structure Determination: Nuclear Magnetic Resonance Spectroscopy. Nuclear Magnetic Resonance Spectroscopy. 11.1 Nuclear Magnetic Resonance John E. McMurry http://www.cengage.com/chemistry/mcmurry Chapter 11 Structure Determination: Nuclear Magnetic Resonance Spectroscopy 11.1 Nuclear Magnetic Resonance Spectroscopy Many atomic nuclei behave

More information

The Four Questions to Ask While Interpreting Spectra. 1. How many different environments are there?

The Four Questions to Ask While Interpreting Spectra. 1. How many different environments are there? 1 H NMR Spectroscopy (#1c) The technique of 1 H NMR spectroscopy is central to organic chemistry and other fields involving analysis of organic chemicals, such as forensics and environmental science. It

More information

Nuclear Magnetic Resonance Spectroscopy

Nuclear Magnetic Resonance Spectroscopy Nuclear Magnetic Resonance Spectroscopy Nuclear magnetic resonance spectroscopy is a powerful analytical technique used to characterize organic molecules by identifying carbonhydrogen frameworks within

More information

Background A nucleus with an odd atomic number or an odd mass number has a nuclear spin that can be observed by NMR spectrometers.

Background A nucleus with an odd atomic number or an odd mass number has a nuclear spin that can be observed by NMR spectrometers. NMR Spectroscopy I Reading: Wade chapter, sections -- -7 Study Problems: -, -7 Key oncepts and Skills: Given an structure, determine which protons are equivalent and which are nonequivalent, predict the

More information

Chemical shift = observed chemical shift in MHz/ frequency of spectrometer (MHz)

Chemical shift = observed chemical shift in MHz/ frequency of spectrometer (MHz) Chapter 4. Physical Basis of NMR Spectroscopy. Today the most widely used method for determining the structure of organic compounds is nuclear magnetic resonance (NMR) spectroscopy. NMR spectroscopy involves

More information

NMR Phenomenon. Nuclear Magnetic Resonance. µ A spinning charged particle generates a magnetic field.

NMR Phenomenon. Nuclear Magnetic Resonance. µ A spinning charged particle generates a magnetic field. NMR Phenomenon Nuclear Magnetic Resonance µ A spinning charged particle generates a magnetic field. A nucleus with a spin angular momentum will generate a magnetic moment (μ). If these tiny magnets are

More information

SIGNAL SPLITTING: Why are there so many peaks all in one area? This is called signal splitting. Example: (image from Illustrated Glossary, splitting)

SIGNAL SPLITTING: Why are there so many peaks all in one area? This is called signal splitting. Example: (image from Illustrated Glossary, splitting) Proton NMR Spectroscopy: Split the signals, not your brain! Before we can understand signal splitting, we have to understand what NMR is. This tutorial will first discuss a few concepts about NMR and then

More information

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY PRINCIPLE AND APPLICATION IN STRUCTURE ELUCIDATION Professor S. SANKARARAMAN Department of Chemistry Indian Institute of Technology Madras Chennai 600 036 sanka@iitm.ac.in

More information

13C NMR Spectroscopy

13C NMR Spectroscopy 13 C NMR Spectroscopy Introduction Nuclear magnetic resonance spectroscopy (NMR) is the most powerful tool available for structural determination. A nucleus with an odd number of protons, an odd number

More information

Chapter 13 Spectroscopy NMR, IR, MS, UV-Vis

Chapter 13 Spectroscopy NMR, IR, MS, UV-Vis Chapter 13 Spectroscopy NMR, IR, MS, UV-Vis Main points of the chapter 1. Hydrogen Nuclear Magnetic Resonance a. Splitting or coupling (what s next to what) b. Chemical shifts (what type is it) c. Integration

More information

Solving Spectroscopy Problems

Solving Spectroscopy Problems Solving Spectroscopy Problems The following is a detailed summary on how to solve spectroscopy problems, key terms are highlighted in bold and the definitions are from the illustrated glossary on Dr. Hardinger

More information

NMR SPECTROSCOPY A N I N T R O D U C T I O N T O... Self-study booklet NUCLEAR MAGNETIC RESONANCE. 4 3 2 1 0 δ PUBLISHING

NMR SPECTROSCOPY A N I N T R O D U C T I O N T O... Self-study booklet NUCLEAR MAGNETIC RESONANCE. 4 3 2 1 0 δ PUBLISHING A N I N T R O D U T I O N T O... NMR SPETROSOPY NULEAR MAGNETI RESONANE 4 3 1 0 δ Self-study booklet PUBLISING NMR Spectroscopy NULEAR MAGNETI RESONANE SPETROSOPY Origin of Spectra Theory All nuclei possess

More information

Nuclear Shielding and 1. H Chemical Shifts. 1 H NMR Spectroscopy Nuclear Magnetic Resonance

Nuclear Shielding and 1. H Chemical Shifts. 1 H NMR Spectroscopy Nuclear Magnetic Resonance NMR Spectroscopy Nuclear Magnetic Resonance Nuclear Shielding and hemical Shifts What do we mean by "shielding?" What do we mean by "chemical shift?" The electrons surrounding a nucleus affect the effective

More information

Examination of Proton NMR Spectra

Examination of Proton NMR Spectra Examination of Proton NMR Spectra What to Look For 1) Number of Signals --- indicates how many "different kinds" of protons are present. 2) Positions of the Signals --- indicates something about magnetic

More information

Nuclear Magnetic Resonance

Nuclear Magnetic Resonance Nuclear Magnetic Resonance NMR is probably the most useful and powerful technique for identifying and characterizing organic compounds. Felix Bloch and Edward Mills Purcell were awarded the 1952 Nobel

More information

Proton Nuclear Magnetic Resonance Spectroscopy

Proton Nuclear Magnetic Resonance Spectroscopy CHEM 334L Organic Chemistry Laboratory Revision 2.0 Proton Nuclear Magnetic Resonance Spectroscopy In this laboratory exercise we will learn how to use the Chemistry Department's Nuclear Magnetic Resonance

More information

Nuclear Magnetic Resonance notes

Nuclear Magnetic Resonance notes Reminder: These notes are meant to supplement, not replace, the laboratory manual. Nuclear Magnetic Resonance notes Nuclear Magnetic Resonance (NMR) is a spectrometric technique which provides information

More information

4. It is possible to excite, or flip the nuclear magnetic vector from the α-state to the β-state by bridging the energy gap between the two. This is a

4. It is possible to excite, or flip the nuclear magnetic vector from the α-state to the β-state by bridging the energy gap between the two. This is a BASIC PRINCIPLES INTRODUCTION TO NUCLEAR MAGNETIC RESONANCE (NMR) 1. The nuclei of certain atoms with odd atomic number, and/or odd mass behave as spinning charges. The nucleus is the center of positive

More information

Nuclear Magnetic Resonance (NMR) Spectroscopy cont... Recommended Reading:

Nuclear Magnetic Resonance (NMR) Spectroscopy cont... Recommended Reading: Applied Spectroscopy Nuclear Magnetic Resonance (NMR) Spectroscopy cont... Recommended Reading: Banwell and McCash Chapter 7 Skoog, Holler Nieman Chapter 19 Atkins, Chapter 18 Relaxation processes We need

More information

A 13 C-NMR spectrum. RF Frequency The intensity of the peak doesn t does not necessarily correlate to the number of carbons.

A 13 C-NMR spectrum. RF Frequency The intensity of the peak doesn t does not necessarily correlate to the number of carbons. 13 -NMR We can examine the nuclear magnetic properties of carbon atoms in a molecule to learn about a molecules structure. Most carbons are 12 ; 12 has an even number of protons and neutrons and cannot

More information

Structure Determination by NMR

Structure Determination by NMR Structure Determination by NMR * Introduction to NMR * 2D NMR, resonance assignments J Correlated Based Experiments * COSY - Correlated Spectroscopy * NOESY - Nuclear Overhauser Effect Spectroscopy * HETCOR

More information

Organic Chemistry Nuclear Magnetic Resonance H. D. Roth. Chemistry 307 Chapter 13 Nuclear Magnetic Resonance

Organic Chemistry Nuclear Magnetic Resonance H. D. Roth. Chemistry 307 Chapter 13 Nuclear Magnetic Resonance Chemistry 307 Chapter 13 Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) spectroscopy is one of three spectroscopic techniques that are useful tools for determining the structures of organic

More information

For example: (Example is from page 50 of the Thinkbook)

For example: (Example is from page 50 of the Thinkbook) SOLVING COMBINED SPECTROSCOPY PROBLEMS: Lecture Supplement: page 50-53 in Thinkbook CFQ s and PP s: page 216 241 in Thinkbook Introduction: The structure of an unknown molecule can be determined using

More information

Molecular spectroscopy III: Nuclear Magnetic Resonance (NMR)

Molecular spectroscopy III: Nuclear Magnetic Resonance (NMR) Molecular spectroscopy III: Nuclear Magnetic Resonance (NMR) Nuclear magnetic resonance (NMR) is a physical phenomenon in which magnetic nuclei in a magnetic field absorb electromagnetic radiation at a

More information

Signal Manipulation. time domain NMR signal in MHz range is converted to khz (audio) range by mixing with the reference ( carrier ) frequency

Signal Manipulation. time domain NMR signal in MHz range is converted to khz (audio) range by mixing with the reference ( carrier ) frequency NMR Spectroscopy: 3 Signal Manipulation time domain NMR signal in MHz range is converted to khz (audio) range by mixing with the reference ( carrier ) frequency Ref in (MHz) mixer Signal in (MHz) Signal

More information

Introduction to NMR Part 1. Revised 2/19/07 Anne M. Gorham

Introduction to NMR Part 1. Revised 2/19/07 Anne M. Gorham Introduction to NMR Part 1 Revised 2/19/07 Anne M. Gorham What is an NMR? Niobium-tin-copper clad coil wound like a spool of thread. The current runs through this coil, creating the magnetic field. This

More information

Chapter 15 NMR Spectroscopy

Chapter 15 NMR Spectroscopy Chempocalypse Now! Chapter 15 NMR Spectroscopy Page 1 Chapter 15 NMR Spectroscopy Parts of Topics A5 and A9 from the IB HL Chemistry Curriculum A5 A.5.1 Nuclear magnetic resonance (NMR) spectrometry (2

More information

IV. Chemical Shifts - δ unit

IV. Chemical Shifts - δ unit Chem 215-216 W11 Notes - Dr. Masato Koreeda Date: January 5, 2011 Topic: _NMR-II page 1 of 10. IV. Chemical Shifts - δ unit Each nucleus in a molecule has a different degree of electron surrounding it.

More information

Nuclear Magnetic Resonance (NMR) Wade Textbook

Nuclear Magnetic Resonance (NMR) Wade Textbook Nuclear Magnetic Resonance (NMR) Wade Textbook Background Is a nondestructive structural analysis technique Has the same theoretical basis as magnetic resonance imaging (MRI) Referring to MRI as nuclear

More information

Symmetric Stretch: allows molecule to move through space

Symmetric Stretch: allows molecule to move through space BACKGROUND INFORMATION Infrared Spectroscopy Before introducing the subject of IR spectroscopy, we must first review some aspects of the electromagnetic spectrum. The electromagnetic spectrum is composed

More information

Instrumental Lab. Nuclear Magnetic Resonance. Dr Alex J. Roche

Instrumental Lab. Nuclear Magnetic Resonance. Dr Alex J. Roche Instrumental Lab Nuclear Magnetic Resonance Dr Alex J. Roche 1 Nuclear Magnetic Resonance (NMR) Spectroscopy NMR is the most powerful analytical tool currently available to an organic chemist. NMR allows

More information

NMR - Basic principles

NMR - Basic principles NMR - Basic principles Subatomic particles like electrons, protons and neutrons are associated with spin - a fundamental property like charge or mass. In the case of nuclei with even number of protons

More information

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY PRINCIPLE AND APPLICATION IN STRUCTURE ELUCIDATION Professor S. SANKARARAMAN Department of Chemistry Indian Institute of Technology Madras Chennai 600 036 sanka@iitm.ac.in

More information

NMR Spectroscopy of Aromatic Compounds (#1e)

NMR Spectroscopy of Aromatic Compounds (#1e) NMR Spectroscopy of Aromatic Compounds (#1e) 1 H NMR Spectroscopy of Aromatic Compounds Erich Hückel s study of aromaticity in the 1930s produced a set of rules for determining whether a compound is aromatic.

More information

Nuclear Magnetic Resonance Spectroscopy

Nuclear Magnetic Resonance Spectroscopy Chapter 8 Nuclear Magnetic Resonance Spectroscopy http://www.yteach.co.uk/page.php/resources/view_all?id=nuclear_magnetic _resonance_nmr_spectroscopy_spin_spectrometer_spectrum_proton_t_pag e_5&from=search

More information

Department of Chemistry College of Science Sultan Qaboos University. Topics and Learning Outcomes

Department of Chemistry College of Science Sultan Qaboos University. Topics and Learning Outcomes Department of Chemistry College of Science Sultan Qaboos University Title : CHEM 3326 (Applied Spectroscopy) Credits : 3 Course Format : 2 lectures and 2 tutorials Course Text : Spectrometric Identification

More information

Christ Church 3 rd Year: Magnetic Resonance. Reading. Topics

Christ Church 3 rd Year: Magnetic Resonance. Reading. Topics Christ Church 3 rd Year: Magnetic Resonance Reading The following sources are recommended for this tutorial: Nuclear Magnetic Resonance by P. J. Hore (Oxford Chemistry Primers). This text contains the

More information

Chemistry 307 Chapter 10 Nuclear Magnetic Resonance

Chemistry 307 Chapter 10 Nuclear Magnetic Resonance Chemistry 307 Chapter 10 Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) spectroscopy is one of three spectroscopic techniques that are useful tools for determining the structures of organic

More information

Nuclear Magnetic Resonance Spectroscopy (NMR)

Nuclear Magnetic Resonance Spectroscopy (NMR) Nuclear Magnetic Resonance Spectroscopy (NMR) NMR is a spectroscopic technique which relies on the magnetic properties of the atomic nucleus. When placed in a strong magnetic field, certain nuclei resonate

More information

Proton NMR. One Dimensional H-NMR. Cl S. Common types of NMR experiments: 1-H NMR

Proton NMR. One Dimensional H-NMR. Cl S. Common types of NMR experiments: 1-H NMR Common types of NMR experiments: 1- NMR Proton NMR ne Dimensional -NMR a. Experiment igh field proton NMR (400Mz). single-pulse experiment. b. Spectral nterpretation i. Number of multiplets gives the different

More information

NUCLEAR MAGNETIC RESONANCE AND INTRODUCTION TO MASS SPECTROMETRY

NUCLEAR MAGNETIC RESONANCE AND INTRODUCTION TO MASS SPECTROMETRY NUCLEAR MAGNETIC RESNANCE AND INTRDUCTIN T MASS SPECTRMETRY A STUDENT SHULD BE ABLE T: 1. Identify and explain the processes involved in proton and carbon-13 nuclear magnetic resonance (NMR), and mass

More information

3H CH 3 group 2H CH 2 group 1H CH or OH group

3H CH 3 group 2H CH 2 group 1H CH or OH group H NMR Spectroscopy and Interpretation: More Detailed than the Summary 89 Introduction to 1H-NMR Spectroscopy Hydrogen NMR spectroscopy is considerably more complex than 1-NMR. The interpretation is more

More information

Introduction to NMR Spectroscopy and Imaging Assignment for Chapter 02: Chemical shift and J Coupling

Introduction to NMR Spectroscopy and Imaging Assignment for Chapter 02: Chemical shift and J Coupling Introduction to NMR Spectroscopy and Imaging Assignment for Chapter 02: Chemical shift and J Coupling 0. Choose the correct one(s) from the following statements or explain briefly your supporting reason

More information

Determination of Molecular Structure by MOLECULAR SPECTROSCOPY

Determination of Molecular Structure by MOLECULAR SPECTROSCOPY Determination of Molecular Structure by MOLEULAR SPETROSOPY hemistry 3 B.Z. Shakhashiri Fall 29 Much of what we know about molecular structure has been learned by observing and analyzing how electromagnetic

More information

NMR Spectroscopy. B = B o - B e ν o = γb/2π

NMR Spectroscopy. B = B o - B e ν o = γb/2π NMR Spectroscopy hem 345 Univ. Wisconsin, Madison hemical Shifts hemical shifts have their origin in the circulation of electrons induced by the magnetic field, which reduces the actual field at the nucleus.

More information

How to Quickly Solve Spectrometry Problems

How to Quickly Solve Spectrometry Problems How to Quickly Solve Spectrometry Problems You should be looking for: Mass Spectrometry (MS) Chemical Formula DBE Infrared Spectroscopy (IR) Important Functional Groups o Alcohol O-H o Carboxylic Acid

More information

Biophysical Chemistry: NMR Spectroscopy

Biophysical Chemistry: NMR Spectroscopy General Principle The Chemical Shift Vrije Universiteit Brussel 28th October 2011 General Principle Outline 1 General Principle Influence of Electron Clouds 2 3 Outline General Principle Influence of Electron

More information

Introduction to Nuclear Magnetic Resonance Spectroscopy

Introduction to Nuclear Magnetic Resonance Spectroscopy Introduction to Nuclear Magnetic Resonance Spectroscopy Dr. Dean L. Olson, NMR Lab Director School of Chemical Sciences University of Illinois Called figures, equations, and tables are from Principles

More information

CHARACTERISTIC FUNCTIONAL-GROUP NMR ABSORPTIONS 13.7. A. NMR Spectra of Alkenes 612 CHAPTER 13 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

CHARACTERISTIC FUNCTIONAL-GROUP NMR ABSORPTIONS 13.7. A. NMR Spectra of Alkenes 612 CHAPTER 13 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 612 APTER 13 NULEAR MAGNETI RESONANE SPETROSOPY PROBLEMS 13.22 The d 1.2 1.5 region of the 300-Mz NMR spectrum of 1-chlorohexane, given in Fig. 13.12, is complex and not first-order. Assuming you could

More information

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. Exam Name SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 1) Calculate the magnetic field that corresponds to the proton resonance frequency of 300.00

More information

The Hydrogen Atom Is a Magnet. http://www.seed.slb.com/en/scictr/watch/gashydrates/detecting.htm

The Hydrogen Atom Is a Magnet. http://www.seed.slb.com/en/scictr/watch/gashydrates/detecting.htm The Hydrogen Atom Is a Magnet Nuclear Magnetic Resonance Spectroscopy (NMR) Proton NMR A hydrogen nucleus can be viewed as a proton, which can be viewed as a spinning charge. As with any spinning charge,

More information

Determining the Structure of an Organic Compound

Determining the Structure of an Organic Compound Determining the Structure of an Organic Compound The analysis of the outcome of a reaction requires that we know the full structure of the products as well as the reactants In the 19 th and early 20 th

More information

April 24, 2015. A Classical Perspective. Exam #3: Solution Key online now! Graded exams by Monday!

April 24, 2015. A Classical Perspective. Exam #3: Solution Key online now! Graded exams by Monday! April 24, 2015 Exam #3: Solution Key online now! Graded exams by Monday! Final Exam Monday, May 4 th, 10:30 a.m. Room: Perkins 107 1 A Classical Perspective A classical view will help us understand the

More information

NMR for Organic Chemistry III

NMR for Organic Chemistry III NMR for rganic Chemistry III Lecture 1 Lecture 2 Lecture 3 Lecture 4 Recap of Key Themes from NMR II + Problems CSY + Problems HSQC + Problems HMBC and Solving Structures + Problems 1 1. Practical Aspects

More information

Nuclear Magnetic Resonance Spectroscopy

Nuclear Magnetic Resonance Spectroscopy Most spinning nuclei behave like magnets. Nuclear Magnetic Resonance Spectroscopy asics owever, as opposed to the behavior of a classical magnet the nuclear spin magnetic moment does not always align with

More information

20. NMR Spectroscopy and Magnetic Properties

20. NMR Spectroscopy and Magnetic Properties 20. NMR Spectroscopy and Magnetic Properties Nuclear Magnetic Resonance (NMR) Spectroscopy is a technique used largely by organic, inorganic, and biological chemists to determine a variety of physical

More information

Nuclear Magnetic Resonance (NMR) Spectroscopy

Nuclear Magnetic Resonance (NMR) Spectroscopy April 28, 2016 Exam #3: Graded exams on Tuesday! Final Exam Tuesday, May 10 th, 10:30 a.m. Room: Votey 207 (tentative) Review Session: Sunday, May 8 th, 4 pm, Kalkin 325 (tentative) Office Hours Next week:

More information

Chapter 13 Mass Spectrometry and Infrared Spectroscopy

Chapter 13 Mass Spectrometry and Infrared Spectroscopy Chapter 13 Mass Spectrometry and Infrared Spectroscopy Copyright 2011 The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Overview of Mass Spectrometry Mass spectrometry

More information

The Experiment Some nuclei have nuclear magnetic moments; just as importantly, some do not

The Experiment Some nuclei have nuclear magnetic moments; just as importantly, some do not Chemistry 2600 Lecture Notes Chapter 15 Nuclear Magnetic Resonance Spectroscopy Page 1 of 23 Structure Determination in Organic Chemistry: NMR Spectroscopy Three main techniques are used to determine the

More information

NMR SPECTROSCOPY. Basic Principles, Concepts, and Applications in Chemistry. Harald Günther University of Siegen, Siegen, Germany.

NMR SPECTROSCOPY. Basic Principles, Concepts, and Applications in Chemistry. Harald Günther University of Siegen, Siegen, Germany. NMR SPECTROSCOPY Basic Principles, Concepts, and Applications in Chemistry Harald Günther University of Siegen, Siegen, Germany Second Edition Translated by Harald Günther JOHN WILEY & SONS Chichester

More information

Using Nuclear Magnetic Resonance Spectroscopy to Identify an Unknown Compound prepared by Joseph W. LeFevre, SUNY Oswego

Using Nuclear Magnetic Resonance Spectroscopy to Identify an Unknown Compound prepared by Joseph W. LeFevre, SUNY Oswego m o d u l a r l a b o r a t o r y p r o g r a m i n c h e m i s t r y publisher:. A. Neidig organic editor: Joe Jeffers TE 711 Using Nuclear Magnetic Resonance Spectroscopy to Identify an Unknown ompound

More information

CHEM 51LB EXP 1 SPECTROSCOPIC METHODS: INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

CHEM 51LB EXP 1 SPECTROSCOPIC METHODS: INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY CHEM 51LB EXP 1 SPECTRSCPIC METHDS: INFRARED AND NUCLEAR MAGNETIC RESNANCE SPECTRSCPY REACTINS: None TECHNIQUES: IR Spectroscopy, NMR Spectroscopy Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy

More information

INFRARED SPECTROSCOPY (IR)

INFRARED SPECTROSCOPY (IR) INFRARED SPECTROSCOPY (IR) Theory and Interpretation of IR spectra ASSIGNED READINGS Introduction to technique 25 (p. 833-834 in lab textbook) Uses of the Infrared Spectrum (p. 847-853) Look over pages

More information

1) A compound gives a mass spectrum with peaks at m/z = 77 (40%), 112 (100%), 114 (33%), and essentially no other peaks. Identify the compound.

1) A compound gives a mass spectrum with peaks at m/z = 77 (40%), 112 (100%), 114 (33%), and essentially no other peaks. Identify the compound. 1) A compound gives a mass spectrum with peaks at m/z = 77 (40%), 112 (100%), 114 (33%), and essentially no other peaks. Identify the compound. First, your molecular ion peak is 112 and you have a M+2

More information

Identifying an Unknown Substance using Infrared Spectroscopy (IR), Carbon-13 Nuclear Magnetic Resonance ( 13 C NMR), and Proton Nuclear Magnetic

Identifying an Unknown Substance using Infrared Spectroscopy (IR), Carbon-13 Nuclear Magnetic Resonance ( 13 C NMR), and Proton Nuclear Magnetic Identifying an Unknown Substance using Infrared Spectroscopy (I), arbon-13 Nuclear Magnetic esonance ( 13 NM), and Proton Nuclear Magnetic esonance ( 1 NM) Identifying an Unknown Substance using Infrared

More information

IR Applied to Isomer Analysis

IR Applied to Isomer Analysis DiscovIR-LC TM Application Note 025 April 2008 Deposition and Detection System IR Applied to Isomer Analysis Infrared spectra provide valuable information about local configurations of atoms in molecules.

More information

How to Report NMR Spectra in a Formal Report

How to Report NMR Spectra in a Formal Report How to Report NMR Spectra in a Formal Report Chem7L Spring 007 ne of the most important elements of authoring an experimental publication is the correct reporting of analytical data. In Experiment, you

More information

(3)

(3) 1. Organic compounds are often identified by using more than one analytical technique. Some of these techniques were used to identify the compounds in the following reactions. C 3 H 7 Br C 3 H 8 O C 3

More information

for excitation to occur, there must be an exact match between the frequency of the applied radiation and the frequency of the vibration

for excitation to occur, there must be an exact match between the frequency of the applied radiation and the frequency of the vibration ! = 1 2"c k (m + M) m M wavenumbers! =!/c = 1/" wavelength frequency! units: cm 1 for excitation to occur, there must be an exact match between the frequency of the applied radiation and the frequency

More information

1 Introduction to NMR Spectroscopy

1 Introduction to NMR Spectroscopy Introduction to NMR Spectroscopy Tremendous progress has been made in NMR spectroscopy with the introduction of multidimensional NMR spectroscopy and pulse Fourier transform NMR spectroscopy. For a deeper

More information

HOMEWORK PROBLEMS: IR SPECTROSCOPY AND 13C NMR. The peak at 1720 indicates a C=O bond (carbonyl). One possibility is acetone:

HOMEWORK PROBLEMS: IR SPECTROSCOPY AND 13C NMR. The peak at 1720 indicates a C=O bond (carbonyl). One possibility is acetone: HMEWRK PRBLEMS: IR SPECTRSCPY AND 13C NMR 1. You find a bottle on the shelf only labeled C 3 H 6. You take an IR spectrum of the compound and find major peaks at 2950, 1720, and 1400 cm -1. Draw a molecule

More information

Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR)

Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR) Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR) A shorter version of the notes, designed to be covered in 4 days. Problems : 1, 2, 3, 4, 7, 10, 11, 19, 20, 22, 24, 27, 30, 34, 35 Absorption of

More information

Lecture Topics: I. IR spectroscopy

Lecture Topics: I. IR spectroscopy IR and Mass Spectrometry Reading: Wade chapter 12, sections 12-1- 12-15 Study Problems: 12-15, 12-16, 12-23, 12-25 Key Concepts and Skills: Given an IR spectrum, identify the reliable characteristic peaks

More information

Valence Bond Theory - Description

Valence Bond Theory - Description Bonding and Molecular Structure - PART 2 - Valence Bond Theory and Hybridization 1. Understand and be able to describe the Valence Bond Theory description of covalent bond formation. 2. Understand and

More information

Infrared Spectroscopy

Infrared Spectroscopy Infrared Spectroscopy 1 Chap 12 Reactions will often give a mixture of products: OH H 2 SO 4 + Major Minor How would the chemist determine which product was formed? Both are cyclopentenes; they are isomers.

More information

Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR)

Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR) Chapter 19 Nuclear Magnetic Resonance Spectroscopy (NMR) 23 pages 2 weeks worth! Problems : 1, 2, 3, 4, 7, 10, 11, 19, 20, 22, 24, 27, 30, 34, 35 Absorption of radio-frequency E from 4-900 MHz (wavelengths

More information

Infrared Spectroscopy and Mass Spectrometry

Infrared Spectroscopy and Mass Spectrometry Infrared Spectroscopy and Mass Spectrometry Introduction It is fundamental for an organic chemist to be able to identify, or characterize, the new compound that he/she has just made. Sometimes this can

More information

Vibrational Spectroscopy Functional Groups

Vibrational Spectroscopy Functional Groups hem 325 Vibrational Spectroscopy Functional roups Bonds to - single N- single - single egions of the I Spectrum The I spectrum normally spans the 4000 cm -1 to 400 cm -1 range (2500 nm to 25000 nm). This

More information

Nuclear Magnetic Resonance Lisa M. Larrimore

Nuclear Magnetic Resonance Lisa M. Larrimore Lisa M. The fundamentals of nuclear magnetic resonance (NMR) spectroscopy were explored on samples containing large numbers of protons. Mineral oil and dilluted solutions of CuSO 4 were placed in a permanent

More information

Infrared Spectroscopy 紅 外 線 光 譜 儀

Infrared Spectroscopy 紅 外 線 光 譜 儀 Infrared Spectroscopy 紅 外 線 光 譜 儀 Introduction Spectroscopy is an analytical technique which helps determine structure. It destroys little or no sample (nondestructive method). The amount of light absorbed

More information

CHE334 Identification of an Unknown Compound By NMR/IR/MS

CHE334 Identification of an Unknown Compound By NMR/IR/MS CHE334 Identification of an Unknown Compound By NMR/IR/MS Purpose The object of this experiment is to determine the structure of an unknown compound using IR, 1 H-NMR, 13 C-NMR and Mass spectroscopy. Infrared

More information

Determination of Equilibrium Constants using NMR Spectrscopy

Determination of Equilibrium Constants using NMR Spectrscopy CHEM 331L Physical Chemistry Laboratory Revision 1.0 Determination of Equilibrium Constants using NMR Spectrscopy In this laboratory exercise we will measure a chemical equilibrium constant using key proton

More information

30 Modern Chemical Techniques

30 Modern Chemical Techniques 30 Modern Chemical Techniques 2. Nuclear magnetic resonance spectroscopy Nuclear magnetic resonance (NMR) spectroscopy gives information on the environment in which the nuclei of atoms are found in molecules

More information

Molecular Models Experiment #1

Molecular Models Experiment #1 Molecular Models Experiment #1 Objective: To become familiar with the 3-dimensional structure of organic molecules, especially the tetrahedral structure of alkyl carbon atoms and the planar structure of

More information

CHEMISTRY 251 Spectroscopy Problems

CHEMISTRY 251 Spectroscopy Problems EMISTRY 251 Spectroscopy Problems The IR below is most likely of a: aldehyde alkane alkene alkyl bromide alkyne The IR below is most likely of a: acyl chloride alcohol 3 amide ether nitrile The IR spectrum

More information

E35 SPECTROSCOPIC TECHNIQUES IN ORGANIC CHEMISTRY

E35 SPECTROSCOPIC TECHNIQUES IN ORGANIC CHEMISTRY E35 SPECTRSCPIC TECNIQUES IN RGANIC CEMISTRY TE TASK To use mass spectrometry and IR, UV/vis and NMR spectroscopy to identify organic compounds. TE SKILLS By the end of the experiment you should be able

More information

Spin-Lattice Relaxation Times

Spin-Lattice Relaxation Times Spin-Lattice Relaxation Times Reading Assignment: T. D. W. Claridge, High Resolution NMR Techniques in Organic Chemistry, Chapter 2; E. Breitmaier, W. Voelter, Carbon 13 NMR Spectroscopy,3rd Ed., 3.3.2.

More information

Spectroscopy. energy Low λ High ν. UV-visible

Spectroscopy. energy Low λ High ν. UV-visible Spectroscopy frequency 10 20 10 18 10 16 10 14 10 12 10 8 Gamma rays X-rays UV IR Microwaves Radiowaves High energy Low λ High ν visible Low energy quantization of energy levels X-Ray UV-visible Infrared

More information

SPECTROSCOPY. NUCLEAR MAGNETIC RESONANCE (NMR) AND INFRARED (IR)

SPECTROSCOPY. NUCLEAR MAGNETIC RESONANCE (NMR) AND INFRARED (IR) EXPERIMENT 9 SPETRSPY. NULEAR MAGNETI RESNANE (NMR) AND INFRARED (IR) Materials Needed approx 100 mg of an ester synthesized in Expt #7 - (octyl acetate, benzyl acetate, or isopentyl acetate) approx 1

More information