3/9/2012. First Ten Alkanes. Simple Organic Chemistry Basic Structure and Nomenclature. (Nomenclature) Rules for Naming Alkanes.

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1 C Simple Organic Chemistry Basic Structure and Nomenclature First Ten Alkanes Formula Name Formula Name CH4 Methane C6H14 Hexane C2H5 Ethane C7H16 Heptane C3H8 Propane C8H18 Octane C4H10 Butane C9H20 Nonane C5H12 Pentane C10H22 becane Alkane = CH2+2 Condensed Structural Formula = CH3(CH 2)CH 3 Straight Chain Akanes arent Straight C - bonds are sp3 hybridized Rules for Naming Alkanes 1. For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon Butane, C4H10 becane, C10H22 4 carbon chain = butane Rules for Naming Alkanes 2. When alkane groups appear as substituents, they are named by dropping the -one and adding -yl. CH 3 Methyl CH 2CH3 Ethyl CH 2CH2CH3 Propyl H r / H; H. Rules for Naming Alkanes 3. The positions of substituent groups are specified by numberin carbon atoms sequentially, starting at the end closest to the branching. 9 the longest chain of ±C1 CH 2CH2CH2CH3 Butyl Methyl Methyl 1

2 9 Rules for Naming Alkanes 4. The location and name of each substituent are followed by the root alkane name. The substituents are listed in alphabetical order (irrespective of any prefix), and the prefixes cli-, tn-, etc. are used to indicate multiple identical substituents. H.4 HC CH: Name: 2-methylbutane 1 carbons = nonane Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon Methyl 34 9carbons =nonone 9carbons =nonane = methyl CH3 methyl,j! chlorine chloro chlorine chloro 8 19 CH3 Step #2: When olkarie groups appear as substituents, they ore named by dropping the -one and odding -yl. 1 9NQT 9 Step #3: The positions of substituent groups ore specified by numbering the longest chain of carbon atoms sequentially, starting at the end closest to the branching. 9 carbons = nonane = methyl chlorine = chloro CH3 Cyclic Alkanes Cyclopropane C3H6 Cyclobutane C4H8 Cyclopentane, C5H10 2-chloro-3, 6-dimethylnonane Cyclohexane, C6H12 Step #4: The location and name of each substituent are followed by the root alkane name. The substituents are Cycloheptane, C7H14 listed in alphabetical order (irrespective of any prefix), and the prefixes di-, tn-, etc. are used to indicate multiple identical substituents. Remember, explicit hydrogens are left out 2

3 -, H2C Structural Isomers Isomers are molecules with the same chemical formula, but different organization of atoms (different bonding) n-pentane. C5H12 H30 Alkenes Contain Carbon-Carbon bouble bonds 1 it bond H H H. H 2-methylpentane, C5H12 2,2-dimethylpropone, CH 12 C; H HCICH H Each carbon is H H sp2 hybndized Ethene 1 ci bond Alkeries are considered unsaturated Geometric Isomerism in Alkenes Unhybridized p orbitals must align, so bond cannot rotate Alkynes Contain Carbon-Carbon Triple Bonds H C H 1 it bond Each carbon is sp hybridized H C H c/s-2-butene trans-2-butene Ethyne 1 it bond 1 ci bond Alkynes ore considered unsaturated Reactions of Alkenes and Alkynes Hydrogenation Propene behydrogenation = CH2 + H2 Ethane Ethene CH3CH3 1 Propane Polymerization Small molecules are joined together to form a large molecule Reactions of Alkenes and Alkynes Combustion CH3CH2CH3 Propane Halogenation 1/r C0 2+ 4H20 1-Pentene 1-2-dibromopentene Substitution CH4+ hv Cl 2 CH 3Cl+HC1 Polyethylene 3

4 - End - Examples: Aromatic Hydrocarbons Cyclic unsaturated hydrocarbons with delocalized electrons The simplest aromatic hydrocarbon is benzene (C6H6) Geometric Isomerism in Aromatics ortho (): meta (m-) two adjacent substituents o- dichlorobenzerie one carbon between substituents OR para (p-) m- dichlorobenzene two carbons between substituents p- dichlorobenzene Hydrocarbon berivatives Class Functional Group General For,nula Alchal hydroxyl group O H P OH Alkyl hohde X P Ether 0 P O P Aldehyde corbonyl group 0 0 II II C H P C H Ketone corbonyl group 0 0 C P C P Carboxylic acid corboxyl group 0 0 C OH C OH Ester 0 0 Alcohols -OH group Higher than expected boiling point (based on molecular weight) Naming is based on longest carbon chain attached to -OH group in -ol C O P C O Amine amine group P N P N P CM NC CH OR, A Aldehydes & Ketones Carboxylic Acids & Esters o 0 b RH RR Mdehyde -al Ketona -one No numbers used for naming aldehydes since group is always on terminal carbon Carboxylic acids are weak acids acetic, salicylic Esters have a fragrant, often pleasant odor Esterification: () RCOH+HORe4RCORl +110 carboxiic akohol ci1er add 4

5 Amines (-NH 2) berivatives of ammonia where one or more N-H bond is replaced by N-C bond mrny rnme Sconda dmm Terndy 4rnrne - N N N N \R4 Figure shows the structures of the 20 amino acids 5

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