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

Size: px
Start display at page:

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

Transcription

1 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 Spectroscopy For Infrared spectroscopy we will run samples using an attenuated total reflectance accessory for our spectrometer. Attenuated total reflectance infrared (ATR/IR) spectra are obtained by placing a drop of a liquid sample or by pressing small amount of a solid sample on an internal reflection element, e.g., zinc selenide (ZnSe) or germanium (Ge). IR radiation enters the end of the internal reflective element and reflects down the length of the crystal. At each internal reflection, the IR radiation actually penetrates a short distance (~1 µm) from the surface of the IRE into the sample (Figure 1). It is this unique physical phenomenon that enables one to obtain infrared spectra of samples placed in contact with the IRE. We are going to use IR spectroscopy for functional group determination; therefore, we will be most interested in the regionsfrom 4000 cm -1 to 1500 cm -1. evanescent wave Sample IRE IRE IR radiation Sample Detector Figure 1. Schematic Representation of Workings of ATR Accessory Instructions for using the IR100 Spectrometer are found on the lab s Canvas website (Under Pagesà Technique). NMR our samples will be submitted for 1 H-NMR ( proton NMR ) and 13 C-NMR on our department s AV400 spectrometer. This is a 400 MHz spectrometer equipped with an autosampler which runs samples robotically. All that you will have to do is prepare your sample. our TA will then submit your samples for analysis. ou will then either be provided with the data to process using the software package M-Nova (the use of which will be demonstrated by your TA), or with the spectra themselves. See the Canvas website (Under Pagesà Technique) for instructions on how to prepare a routine NMR sample. Mass Spectrometry The information provided by mass spectroscopy is used in three ways when identifying unknown organic compounds: determination of molecular weight, determination of molecular formula, and the determination of molecular structures. The sample is introduced into the mass spectrometer through an inlet system. In our case, the sample is introduced through a capillary gas chromatograph. The mass spectrum is then run on a single pure compound as it eludes from the gas chromatograph. From the gas chromatograph, the sample enters a section of the mass spectrometer called the ionization chamber. In the ionization chamber, a ray of very high-energy electrons bombards the sample. If these electrons collide with a sample molecule they have enough energy to knock electrons out of the sample molecules. The result is a radical cation of the original sample molecule known as the molecular ion (M +. ). 1

2 M + e M + 2e From the ionization chamber the ionized molecules are accelerated and focused into a beam of rapidly moving ions by a means of charged plates. These ions are introduced into a chamber that is spherically surrounded by electrodes. The electric field produced by these electrodes causes the ions to travel in circles inside this chamber. The electric field is slowly varied to allow sequential release of ions of increasing mass to the detector (Figure 2). The plot of ion abundance versus mass-tocharge (m/z) ratio is known as the mass spectrum. Since most molecules only lose one electron the charge on each ion is typically one. If the charge is one the mass-to-charge ratio is equal to the mass of the ion. In a typical mass spectrum, many different m/z peaks will be observed because after being hit by a high-energy electron, molecules have a tendency to break apart or fragment. A peak is observed in the mass spectrum for each fragment of the molecule that retained a positive charge. Figure 2. Schematic Diagram of a Quadrupole Ion Storage Trap Mass Spectrometer with Attached Gas Chromatograph The most abundant ion formed in the mass spectrometer gives the tallest peak in the mass spectrum. This peak, called the base peak, is often not the heaviest ion (the peak most to the right). The tallest peak corresponds to the most stable cation and is often the result of the molecular ion fragmenting due to the large amount of energy it possesses after being hit by an electron in the ionization chamber. Since molecules tend to fragment to form more stable cations, carefully studying the fragmentation peaks can provide a large amount of structural information about the compound. The heaviest ion peak is usually the molecular ion; however, at times the molecular ion is too unstable to make it from the ionization chamber to the detector before completely fragmenting in which case no molecular ion is seen. The mass of the molecular ion is the m/e value from the spectrum assuming only one electron was removed from the molecule. (It is extremely rare for a single small molecule to lose more than one electron so this is a safe assumption.) The mass of the molecular ion is equivalent to the molecular weight of the compound. The mass spectra shows the molecular weight of individual ions; the intensity of the peak corresponding to the number of those ions hitting the detector. If a particular molecule of a compound contains an atom of a heavier isotope the spectra will show a peak at a larger m/z value. The intensity of this new peak will depend on how many molecules contain this heavier isotope. Since almost all atoms exist in nature in multiple isotopic forms, in theory, the mass spectrum should show peaks for molecules containing all these isotopes. In practice, the natural abundance of most atomic isotopes is too low for the mass spectrometer to detect molecules containing these isotopes. However, certain isotopes have a high enough natural abundance that molecules containing these isotopes are observable in the mass spectrum. When these peaks are observable in the mass spectrum they provide very valuable information about the molecular formula of the compound. The masses of these isotopes are usually one or two mass units above the mass of the most abundant isotope. Therefore, in addition to looking for the molecular ion peak (M + ), it is worth attempting to locate the M + 1 and M + 2 peaks. Comparing the intensities of the M + peak and the M + 2 peak provides information about the number of sulfurs, silicons and particularly halogens in the molecule. The intensity of the M + 1 peak is very valuable in determining the number of carbons in the molecule. 2

3 In this lab, mass spectra of the unknowns will be taken and provided for you. Determining the Structure of an Unknown Just like a detective you now have collected all the evidence you need to determine the structure of your unknown. ou just need to put all the clues together to solve the mystery. Like any detective investigation there is not a set linear way of examining the evidence that leads to the solution in every case. Every investigation and its corresponding evidence are unique. The approach presented here will get you close but in the end you still need to be the one to put all the pieces together. Also like a detective, it is useful to have a notebook to record key information in as you collect it. Functional Groups From the Infrared: Assign major peaks between 4000 cm -1 and 1500 cm -1 in the Infrared spectra to their corresponding functional groups. Pay particular attention for peaks corresponding to OH and C=O Molecular Weight and Molecular Formula by Mass Spectroscopy: Identify the cluster of peaks corresponding to the molecular ion (the highest mass peaks not the tallest). Determine if the unknown compound contains chlorine, or bromine and if so how many of each by comparing the pattern of peaks in the mass spectrum to the patterns given below. (Be sure to check the printed list of peaks not just the spectra.) Each peak in the patterns are separated by two mass units. Very small peaks that differ from the larger peaks by single mass units are not shown below but will also be very important in determining the molecular formula of your unknown. If you determine that the molecule contains chlorine or bromine draw them in your investigation notebook. The most substantial contributors to the M + 1 peak are molecules of the molecular ion containing carbon-13. The odds that a molecule contains a carbon-13 atom are dependent the number of carbons in the molecule and the percent of naturally occurring carbon that is carbon-13. Since we know that 1.08% of carbon is carbon-13 and we can determine the odds that a molecule contains a carbon-13 by comparing intensity of the M + 1 peak to the intensity of the molecular ion peak (M + ) we can calculate how many carbons are in our molecule. ou can do the algebra if you like but the resulting formula relating the number carbons in the molecule to the relative sizes of the M + and M + 1 peaks is given below. Since the M + 1 peak is usually a weak peak the error in its intensity can be quite substantial. As a result this calculation is really only an approximation. Perform the calculation and record the calculated number of carbons in your investigation notebook. # of carbons = (intensity of the M + 1 peak) [(intensity of the M + peak) + (intensity of the M + 1 peak)] x Add up the atomic weights of all the atoms you have determined are in the molecule so far including any functional groups identified by Infrared Spectroscopy. If more than one isotope is common for any of these atoms use the lowest weight isotope (e.g. use 35 for chlorine, and 79 for bromine). Subtract this number from the molecular weight of the compound as determined from the molecular ion peak in the mass spectra. If your molecule contains halogens use the lowest m/e value from the molecular cluster. The resulting number corresponds to the number of hydrogens in the molecule. If you get a negative number reduce the number of carbons by one and recalculate. If the number of hydrogens plus halogens, minus two, is more than twice the number of carbons then increase the number of carbons by one and recalculate. 3

4 Degrees of Hydrogen Deficiency Determine the number of rings plus π-bonds in your molecule by calculating the degrees of hydrogen deficiency. Record this value in your investigation notebook. If the value comes out to four or higher there is a good chance your compound contains an aromatic ring. Verify this by looking in the proton NMR for peaks around 7.0 ppm and the 13 C-NMR for peaks around 130 ppm. If you have an aromatic ring record this in your investigation notebook as well. D.H.D. = (# of C x 2) + (# of N) (# of H) - (# of halogens) 2 Interpretation of 13 C-NMR Count the number of peaks in the 13 C-NMR. (Note, the three equal sized peaks centered at 77 ppm are the carbon o f CDCl 3, the solvent; do not count these three peaks.) If this number is less than the number of carbons you determined the molecule has then the molecule must possess symmetry making some of the carbons equivalent to each other. This symmetry determination is particularly useful if your compound contains a benzene ring. Since you know benzene rings have six carbons there should be six peaks around 130 ppm unless there is symmetry within the ring. This symmetry determination can help you determine the substitution pattern on the ring. A few examples are given below. The rings possessing a plane of symmetry will only give four peaks in the 13 C-NMR instead of six. plane of symmetry plane of symmetry plane of symmetry plane of symmetry If the Infrared spectra indicated that there are particular functional groups in the molecule verify that the appropriate 13 C- NMR peaks exist. That is if the Infrared spectra indicated a carbonyl group there should be a 13 C-NMR peak around 195 ppm. If the Infrared spectra indicated an alcohol there should be a 13 C-NMR peak around 60 ppm. If this verification fails recheck your Infrared interpretation. If the interpretation is correct you may need to rerun the Infrared spectrum. Interpretation of 1 H-NMR Excluding obvious impurities and the TMS peak, add up all the integration numbers from the bottom of the spectra. Divide this number by the number of hydrogens in the molecule. This number corresponds to the integration of one hydrogen in arbitrary units. Using this value calculate the number of hydrogens producing each peak in the NMR. As a first approximation, assume that signals integrating to three hydrogens are produced by CH 3 s. For a signal that integrates to two hydrogens there are three possibilities: a CH 2, two identical CH (would have to see symmetry in 13 C-NMR), or an NH 2. Signals that integrate to one are produced by CH, OH, or one of the hydrogens of a CH 2 when the CH 2 is not free to rotate. Any signals that integrate to more than three imply that the molecule must have symmetry, which should also be observed in the 13 C-NMR. The integration of the peaks corresponding to the aromatic hydrogens (peaks at approximately 7.0 ppm) provides information about the substitution of the benzene (five aromatic hydrogens implies mono substituted, four aromatic hydrogens implies disubstituted, three aromatic hydrogens implies trisubstituted etc.). 4

5 Determine the splitting pattern of each signal in the NMR. Using the N + 1 rule determine how many hydrogens are on atoms adjacent to the hydrogens producing the signal (N is the number of hydrogens on adjacent atoms and N + 1 is the number of peaks the signal is split into). For example a doublet implies one adjacent hydrogen, a triplet implies two adjacent hydrogens, a quartet implies three adjacent hydrogens and a quintet implies four adjacent hydrogens. In your investigation notebook draw out any fragments you can deduce from this analysis. Remember if you deduce that there is a CH 2 next to a CH somewhere in the NMR spectra you must account for a CH that can be next to a CH 2 and that these two are the same fragment of the molecule (do not count them twice). The Final Structure Using all the information you have in your investigation notebook (molecular formula, functional groups, existence of an aromatic ring, symmetry, and the molecular fragments from 1 H-NMR) propose possible structures that are supported by all the evidence. Keep in mind that you cannot violate the octet rule when proposing your structures. There should be very few possible structures that fit all the information you have collected so far. Check each proposed structure to insure they are completely consistent with all the collected spectra, particularly the 1 H-NMR and 13 C-NMR including observed chemical shifts. Laboratory Report Hints The data section should list the location and type of peaks seen in the spectra. ou can also tape copies of your spectra into your lab notebook. In the discussion, guide the reader through your reasoning in determining the structure of your unknown and what you determined the structure to be. If there are any ambiguities you should mention them and what they may mean to your final structural assignment. The report should be written as if the reader DOES NOT has access to the original spectra. ou must tell where peaks are and what they look like. Avoid statements like The peak labeled A in the 1 H-NMR indicates the presence of aromatic hydrogens. The reader does not have the spectra so they cannot see the peak labeled A. A better way would be, The two doublets each integrating to two hydrogens at 7.3 ppm and 6.9 ppm in the 1 H-NMR indicate the presence of aromatic hydrogens. 5

6 Spectroscopy: Procedure Hazards: Deuterochloroform is a possible carcinogen and an irritant. The unknowns could have one or more of the following properties: flammable; can cause skin/eye/respiratory track irritation; lachrymator. Acetone is flammable. Wear goggles and gloves, work in the fume hood, and keep chemical containers closed when not in use. Day 1 1. Obtain a sample of an unknown compound from your TA. Record its number in your lab notebook. 2. Prepare an NMR sample of your compound, using CDCl 3 as the solvent. See the handout on Canvas under Pagesà Techniques for instructions. 3. Obtain an IR spectrum of the unknown. See the handout on Canvas under Pagesà Techniques for instructions. Day 2 our TA will provide you with NMR and MS data for your unknown. Copies of all spectra can be taped into your notebook. Analyze your spectral data and determine as best you can the structure of your unknown compound. Refer to the Spectroscopy handout on Canvas under Pagesà Spectroscopy for additional information on spectroscopic techniques and interpretation of results.

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

Mass Spectrometry. Overview

Mass Spectrometry. Overview Mass Spectrometry Overview Mass Spectrometry is an analytic technique that utilizes the degree of deflection of charged particles by a magnetic field to find the relative masses of molecular ions and fragments.2

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

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

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

0 10 20 30 40 50 60 70 m/z

0 10 20 30 40 50 60 70 m/z Mass spectrum for the ionization of acetone MS of Acetone + Relative Abundance CH 3 H 3 C O + M 15 (loss of methyl) + O H 3 C CH 3 43 58 0 10 20 30 40 50 60 70 m/z It is difficult to identify the ions

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

Nuclear Structure. particle relative charge relative mass proton +1 1 atomic mass unit neutron 0 1 atomic mass unit electron -1 negligible mass

Nuclear Structure. particle relative charge relative mass proton +1 1 atomic mass unit neutron 0 1 atomic mass unit electron -1 negligible mass Protons, neutrons and electrons Nuclear Structure particle relative charge relative mass proton 1 1 atomic mass unit neutron 0 1 atomic mass unit electron -1 negligible mass Protons and neutrons make up

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

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

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

electron does not become part of the compound; one electron goes in but two electrons come out.

electron does not become part of the compound; one electron goes in but two electrons come out. Characterization Techniques for Organic Compounds. When we run a reaction in the laboratory or when we isolate a compound from nature, one of our first tasks is to identify the compound that we have obtained.

More information

Pesticide Analysis by Mass Spectrometry

Pesticide Analysis by Mass Spectrometry Pesticide Analysis by Mass Spectrometry Purpose: The purpose of this assignment is to introduce concepts of mass spectrometry (MS) as they pertain to the qualitative and quantitative analysis of organochlorine

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

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

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

F321 THE STRUCTURE OF ATOMS. ATOMS Atoms consist of a number of fundamental particles, the most important are... in the nucleus of an atom

F321 THE STRUCTURE OF ATOMS. ATOMS Atoms consist of a number of fundamental particles, the most important are... in the nucleus of an atom Atomic Structure F32 TE STRUCTURE OF ATOMS ATOMS Atoms consist of a number of fundamental particles, the most important are... Mass / kg Charge / C Relative mass Relative Charge PROTON NEUTRON ELECTRON

More information

Chapter 1: Moles and equations. Learning outcomes. you should be able to:

Chapter 1: Moles and equations. Learning outcomes. you should be able to: Chapter 1: Moles and equations 1 Learning outcomes you should be able to: define and use the terms: relative atomic mass, isotopic mass and formula mass based on the 12 C scale perform calculations, including

More information

Suggested solutions for Chapter 3

Suggested solutions for Chapter 3 s for Chapter PRBLEM Assuming that the molecular ion is the base peak (00% abundance) what peaks would appear in the mass spectrum of each of these molecules: (a) C5Br (b) C60 (c) C64Br In cases (a) and

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

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

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

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

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

Experiment 11. Infrared Spectroscopy

Experiment 11. Infrared Spectroscopy Chem 22 Spring 2010 Experiment 11 Infrared Spectroscopy Pre-lab preparation. (1) In Ch 5 and 12 of the text you will find examples of the most common functional groups in organic molecules. In your notebook,

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

Chapter 3. Mass Relationships in Chemical Reactions

Chapter 3. Mass Relationships in Chemical Reactions Chapter 3 Mass Relationships in Chemical Reactions This chapter uses the concepts of conservation of mass to assist the student in gaining an understanding of chemical changes. Upon completion of Chapter

More information

CHEM 51LB: EXPERIMENT 5 SPECTROSCOPIC METHODS: INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

CHEM 51LB: EXPERIMENT 5 SPECTROSCOPIC METHODS: INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY CHEM 51LB: EXPERIMENT 5 SPECTROSCOPIC METHODS: INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY REACTIONS: None TECHNIQUES: IR, NMR Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy are

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

Background Information

Background Information 1 Gas Chromatography/Mass Spectroscopy (GC/MS/MS) Background Information Instructions for the Operation of the Varian CP-3800 Gas Chromatograph/ Varian Saturn 2200 GC/MS/MS See the Cary Eclipse Software

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

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

Ultraviolet Spectroscopy

Ultraviolet Spectroscopy Ultraviolet Spectroscopy The wavelength of UV and visible light are substantially shorter than the wavelength of infrared radiation. The UV spectrum ranges from 100 to 400 nm. A UV-Vis spectrophotometer

More information

NMR and other Instrumental Techniques in Chemistry and the proposed National Curriculum.

NMR and other Instrumental Techniques in Chemistry and the proposed National Curriculum. NMR and other Instrumental Techniques in Chemistry and the proposed National Curriculum. Dr. John Jackowski Chair of Science, Head of Chemistry Scotch College Melbourne john.jackowski@scotch.vic.edu.au

More information

Amount of Substance. http://www.avogadro.co.uk/definitions/elemcompmix.htm

Amount of Substance. http://www.avogadro.co.uk/definitions/elemcompmix.htm Page 1 of 14 Amount of Substance Key terms in this chapter are: Element Compound Mixture Atom Molecule Ion Relative Atomic Mass Avogadro constant Mole Isotope Relative Isotopic Mass Relative Molecular

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

Organic Spectroscopy. UV - Ultraviolet-Visible Spectroscopy. !! 200-800 nm. Methods for structure determination of organic compounds:

Organic Spectroscopy. UV - Ultraviolet-Visible Spectroscopy. !! 200-800 nm. Methods for structure determination of organic compounds: Organic Spectroscopy Methods for structure determination of organic compounds: X-ray rystallography rystall structures Mass spectroscopy Molecular formula -----------------------------------------------------------------------------

More information

Organic Spectroscopy

Organic Spectroscopy 1 Organic Spectroscopy Second Year, Michaelmas term, 8 lectures: Dr TDW Claridge & Prof BG Davis Lectures 1 4 highlight the importance of spectroscopic methods in the structural elucidation of organic

More information

Mass Spec - Fragmentation

Mass Spec - Fragmentation Mass Spec - Fragmentation An extremely useful result of EI ionization in particular is a phenomenon known as fragmentation. The radical cation that is produced when an electron is knocked out of a neutral

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

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

The Fundamentals of Infrared Spectroscopy. Joe Van Gompel, PhD

The Fundamentals of Infrared Spectroscopy. Joe Van Gompel, PhD TN-100 The Fundamentals of Infrared Spectroscopy The Principles of Infrared Spectroscopy Joe Van Gompel, PhD Spectroscopy is the study of the interaction of electromagnetic radiation with matter. The electromagnetic

More information

ANALYSIS OF ASPIRIN INFRARED (IR) SPECTROSCOPY AND MELTING POINT DETERMINATION

ANALYSIS OF ASPIRIN INFRARED (IR) SPECTROSCOPY AND MELTING POINT DETERMINATION Chem 306 Section (Circle) M Tu W Th Name Partners Date ANALYSIS OF ASPIRIN INFRARED (IR) SPECTROSCOPY AND MELTING POINT DETERMINATION Materials: prepared acetylsalicylic acid (aspirin), stockroom samples

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

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name 1) Which compound would be expected to show intense IR absorption at 3300 cm-1? A) butane B) CH3CH2C CH C)CH3C CCH3 D) but-1-ene 1) 2) Which compound would be expected to show intense IR absorption

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

Application Note AN4

Application Note AN4 TAKING INVENTIVE STEPS IN INFRARED. MINIATURE INFRARED GAS SENSORS GOLD SERIES UK Patent App. No. 2372099A USA Patent App. No. 09/783,711 World Patents Pending INFRARED SPECTROSCOPY Application Note AN4

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

Electrons in Atoms & Periodic Table Chapter 13 & 14 Assignment & Problem Set

Electrons in Atoms & Periodic Table Chapter 13 & 14 Assignment & Problem Set Electrons in Atoms & Periodic Table Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8. Electrons in Atoms & Periodic Table 2 Study Guide: Things You

More information

A LEVEL. Type of resource H433 CHEMISTRY B. Theme: Carbon-13 MMR. October 2015

A LEVEL. Type of resource H433 CHEMISTRY B. Theme: Carbon-13 MMR. October 2015 A LEVEL Type of resource H433 CHEMISTRY B (SALTERS) Theme: Carbon-13 MMR October 2015 We will inform centres about any changes to the specification. We will also publish changes on our website. The latest

More information

Chapter 5 Organic Spectrometry

Chapter 5 Organic Spectrometry Chapter 5 Organic Spectrometry from Organic Chemistry by Robert C. Neuman, Jr. Professor of Chemistry, emeritus University of California, Riverside orgchembyneuman@yahoo.com

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

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

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

Element of same atomic number, but different atomic mass o Example: Hydrogen

Element of same atomic number, but different atomic mass o Example: Hydrogen Atomic mass: p + = protons; e - = electrons; n 0 = neutrons p + + n 0 = atomic mass o For carbon-12, 6p + + 6n 0 = atomic mass of 12.0 o For chlorine-35, 17p + + 18n 0 = atomic mass of 35.0 atomic mass

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

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

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

Chapter 2 Atoms, Ions, and the Periodic Table

Chapter 2 Atoms, Ions, and the Periodic Table Chapter 2 Atoms, Ions, and the Periodic Table 2.1 (a) neutron; (b) law of conservation of mass; (c) proton; (d) main-group element; (e) relative atomic mass; (f) mass number; (g) isotope; (h) cation; (i)

More information

Molecular Formula Determination

Molecular Formula Determination Molecular Formula Determination Classical Approach Qualitative elemental analysis Quantitative elemental analysis Determination of empirical formula Molecular weight determination Molecular formula determination

More information

List the 3 main types of subatomic particles and indicate the mass and electrical charge of each.

List the 3 main types of subatomic particles and indicate the mass and electrical charge of each. Basic Chemistry Why do we study chemistry in a biology course? All living organisms are composed of chemicals. To understand life, we must understand the structure, function, and properties of the chemicals

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

APS Science Curriculum Unit Planner

APS Science Curriculum Unit Planner APS Science Curriculum Unit Planner Grade Level/Subject Chemistry Stage 1: Desired Results Enduring Understanding Topic 1: Elements and the Periodic Table: The placement of elements on the periodic table

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

Reactions of Aldehydes and Ketones

Reactions of Aldehydes and Ketones Reactions of Aldehydes and Ketones Structure Deduction using lassification Tests 1 Determination of Structure Determining the structure of an unknown organic compound is an exercise in deductive reasoning.

More information

CH3 Stoichiometry. The violent chemical reaction of bromine and phosphorus. P.76

CH3 Stoichiometry. The violent chemical reaction of bromine and phosphorus. P.76 CH3 Stoichiometry The violent chemical reaction of bromine and phosphorus. P.76 Contents 3.1 Counting by Weighing 3.2 Atomic Masses 3.3 The Mole 3.4 Molar Mass 3.5 Percent Composition of Compounds 3.6

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

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

AMD Analysis & Technology AG

AMD Analysis & Technology AG AMD Analysis & Technology AG Application Note 120419 Author: Karl-Heinz Maurer APCI-MS Trace Analysis of volatile organic compounds in ambient air A) Introduction Trace analysis of volatile organic compounds

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

The photoionization detector (PID) utilizes ultraviolet

The photoionization detector (PID) utilizes ultraviolet Chapter 6 Photoionization Detectors The photoionization detector (PID) utilizes ultraviolet light to ionize gas molecules, and is commonly employed in the detection of volatile organic compounds (VOCs).

More information

For convenience, we may consider an atom in two parts: the nucleus and the electrons.

For convenience, we may consider an atom in two parts: the nucleus and the electrons. Atomic structure A. Introduction: In 1808, an English scientist called John Dalton proposed an atomic theory based on experimental findings. (1) Elements are made of extremely small particles called atoms.

More information

Molecular Models in Biology

Molecular Models in Biology Molecular Models in Biology Objectives: After this lab a student will be able to: 1) Understand the properties of atoms that give rise to bonds. 2) Understand how and why atoms form ions. 3) Model covalent,

More information

Titan: The Solar System s Abiotic Petroleum Factory

Titan: The Solar System s Abiotic Petroleum Factory Titan: The Solar System s Abiotic Petroleum Factory J. Hunter Waite, Ph.D. Institute Scientist Space Science & Engineering Division Southwest Research Institute Titan: The Solar System s Abiotic Petroleum

More information

Chemistry Diagnostic Questions

Chemistry Diagnostic Questions Chemistry Diagnostic Questions Answer these 40 multiple choice questions and then check your answers, located at the end of this document. If you correctly answered less than 25 questions, you need to

More information

Health Science Chemistry I CHEM-1180 Experiment No. 15 Molecular Models (Revised 05/22/2015)

Health Science Chemistry I CHEM-1180 Experiment No. 15 Molecular Models (Revised 05/22/2015) (Revised 05/22/2015) Introduction In the early 1900s, the chemist G. N. Lewis proposed that bonds between atoms consist of two electrons apiece and that most atoms are able to accommodate eight electrons

More information

Trends of the Periodic Table Diary

Trends of the Periodic Table Diary Trends of the Periodic Table Diary Trends are patterns of behaviors that atoms on the periodic table of elements follow. Trends hold true most of the time, but there are exceptions, or blips, where the

More information

Infrared Spectroscopy: Theory

Infrared Spectroscopy: Theory u Chapter 15 Infrared Spectroscopy: Theory An important tool of the organic chemist is Infrared Spectroscopy, or IR. IR spectra are acquired on a special instrument, called an IR spectrometer. IR is used

More information

Atomic Theory Part 1

Atomic Theory Part 1 Atomic Theory Part 1 Reading: Ch 2 sections 1 6, 8 Homework: Chapter 2: 39, 47, 43, 49, 51*, 53, 55, 57, 71, 73, 77, 99, 103 (optional) * = important homework question The Atomic Theory (John Dalton, 1803)

More information

EXPERIMENT Aspirin: Synthesis and NMR Analysis

EXPERIMENT Aspirin: Synthesis and NMR Analysis EXPERIMENT Aspirin: Synthesis and NMR Analysis Introduction: When salicylic acid reacts with acetic anhydride in the presence of an acid catalyst, acetylsalicylic acid, or aspirin, is produced according

More information

Simple vs. True. Simple vs. True. Calculating Empirical and Molecular Formulas

Simple vs. True. Simple vs. True. Calculating Empirical and Molecular Formulas Calculating Empirical and Molecular Formulas Formula writing is a key component for success in chemistry. How do scientists really know what the true formula for a compound might be? In this lesson we

More information

QUANTITATIVE INFRARED SPECTROSCOPY. Willard et. al. Instrumental Methods of Analysis, 7th edition, Wadsworth Publishing Co., Belmont, CA 1988, Ch 11.

QUANTITATIVE INFRARED SPECTROSCOPY. Willard et. al. Instrumental Methods of Analysis, 7th edition, Wadsworth Publishing Co., Belmont, CA 1988, Ch 11. QUANTITATIVE INFRARED SPECTROSCOPY Objective: The objectives of this experiment are: (1) to learn proper sample handling procedures for acquiring infrared spectra. (2) to determine the percentage composition

More information

AP Chemistry A. Allan Chapter 8 Notes - Bonding: General Concepts

AP Chemistry A. Allan Chapter 8 Notes - Bonding: General Concepts AP Chemistry A. Allan Chapter 8 Notes - Bonding: General Concepts 8.1 Types of Chemical Bonds A. Ionic Bonding 1. Electrons are transferred 2. Metals react with nonmetals 3. Ions paired have lower energy

More information

Atomic Masses. Chapter 3. Stoichiometry. Chemical Stoichiometry. Mass and Moles of a Substance. Average Atomic Mass

Atomic Masses. Chapter 3. Stoichiometry. Chemical Stoichiometry. Mass and Moles of a Substance. Average Atomic Mass Atomic Masses Chapter 3 Stoichiometry 1 atomic mass unit (amu) = 1/12 of the mass of a 12 C atom so one 12 C atom has a mass of 12 amu (exact number). From mass spectrometry: 13 C/ 12 C = 1.0836129 amu

More information

Atomic Calculations. 2.1 Composition of the Atom. number of protons + number of neutrons = mass number

Atomic Calculations. 2.1 Composition of the Atom. number of protons + number of neutrons = mass number 2.1 Composition of the Atom Atomic Calculations number of protons + number of neutrons = mass number number of neutrons = mass number - number of protons number of protons = number of electrons IF positive

More information

Introduction to Geiger Counters

Introduction to Geiger Counters Introduction to Geiger Counters A Geiger counter (Geiger-Muller tube) is a device used for the detection and measurement of all types of radiation: alpha, beta and gamma radiation. Basically it consists

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

Strategies for Developing Optimal Synchronous SIM-Scan Acquisition Methods AutoSIM/Scan Setup and Rapid SIM. Technical Overview.

Strategies for Developing Optimal Synchronous SIM-Scan Acquisition Methods AutoSIM/Scan Setup and Rapid SIM. Technical Overview. Strategies for Developing Optimal Synchronous SIM-Scan Acquisition Methods AutoSIM/Scan Setup and Rapid SIM Technical Overview Introduction The 5975A and B series mass selective detectors (MSDs) provide

More information

Chemical Composition Review Mole Calculations Percent Composition. Copyright Cengage Learning. All rights reserved. 8 1

Chemical Composition Review Mole Calculations Percent Composition. Copyright Cengage Learning. All rights reserved. 8 1 Chemical Composition Review Mole Calculations Percent Composition Copyright Cengage Learning. All rights reserved. 8 1 QUESTION Suppose you work in a hardware store and a customer wants to purchase 500

More information

Ionic and Metallic Bonding

Ionic and Metallic Bonding Ionic and Metallic Bonding BNDING AND INTERACTINS 71 Ions For students using the Foundation edition, assign problems 1, 3 5, 7 12, 14, 15, 18 20 Essential Understanding Ions form when atoms gain or lose

More information

Chem101: General Chemistry Lecture 9 Acids and Bases

Chem101: General Chemistry Lecture 9 Acids and Bases : General Chemistry Lecture 9 Acids and Bases I. Introduction A. In chemistry, and particularly biochemistry, water is the most common solvent 1. In studying acids and bases we are going to see that water

More information

Getting the most from this book...4 About this book...5

Getting the most from this book...4 About this book...5 Contents Getting the most from this book...4 About this book....5 Content Guidance Topic 1 Atomic structure and the periodic table...8 Topic 2 Bonding and structure...14 Topic 2A Bonding....14 Topic 2B

More information

Stoichiometry. What is the atomic mass for carbon? For zinc?

Stoichiometry. What is the atomic mass for carbon? For zinc? Stoichiometry Atomic Mass (atomic weight) Atoms are so small, it is difficult to discuss how much they weigh in grams We use atomic mass units an atomic mass unit (AMU) is one twelfth the mass of the catbon-12

More information

Chapter 8 Concepts of Chemical Bonding

Chapter 8 Concepts of Chemical Bonding Chapter 8 Concepts of Chemical Bonding Chemical Bonds Three types: Ionic Electrostatic attraction between ions Covalent Sharing of electrons Metallic Metal atoms bonded to several other atoms Ionic Bonding

More information

How To Use Gc-Ms

How To Use Gc-Ms The CHROMacademy Essential Guide Understanding GC-MS Analysis Part 1 Speakers John Hinshaw GC Dept. Dean CHROMacademy Tony Taylor Technical Director Crawford Scientific Moderator M ( g ) e M ( g ) 2e Peter

More information

Chapter 4: Structure and Properties of Ionic and Covalent Compounds

Chapter 4: Structure and Properties of Ionic and Covalent Compounds Chapter 4: Structure and Properties of Ionic and Covalent Compounds 4.1 Chemical Bonding o Chemical Bond - the force of attraction between any two atoms in a compound. o Interactions involving valence

More information

2 The Structure of Atoms

2 The Structure of Atoms CHAPTER 4 2 The Structure of Atoms SECTION Atoms KEY IDEAS As you read this section, keep these questions in mind: What do atoms of the same element have in common? What are isotopes? How is an element

More information

Solution problem 13: Absorption of Light by Molecules

Solution problem 13: Absorption of Light by Molecules Solution problem 13: Absorption of Light by Molecules 13.1 A = εcd = 1.5 10 5 mol -1 L cm -1 4 10-6 mol L -1 10-4 cm = 6 10-5 Since A = log(p 0 /P), the ratio P/P 0 is 0.999862. This is the percentage

More information

Electrospray Ion Trap Mass Spectrometry. Introduction

Electrospray Ion Trap Mass Spectrometry. Introduction Electrospray Ion Source Electrospray Ion Trap Mass Spectrometry Introduction The key to using MS for solutions is the ability to transfer your analytes into the vacuum of the mass spectrometer as ionic

More information