西北农林科技大学：《有机化学 Organic chemistry》课程教学课件（2012）Chapter 04 Structure and Stereochemistry of Alkanes

0 花华院 Organic Chemistry,6th Edition L.G.Wade,Jr. Chapter 4 Structure and Stereochemistry of Alkanes By Junru Wang Email:wangjr07@163.com

By Junru Wang Email: wangjr07@163.com Chapter 4 Structure and Stereochemistry of Alkanes Organic Chemistry, 6th Edition L. G. Wade, Jr

0环4 Key Notes 花率院 ■Mechanisms ■Conformation ■Ring strain ■Conformers ■Cis-trans isomers

Key Notes Mechanisms Conformation Ring strain Conformers Cis-trans isomers

0 CONTENTS 发牌院 Classification of Hydrocarbons Physical properties Reactions Mechanisms of Alkanes Structure Conformation of Alkanes Conformation of Cycloalkanes

CONTENTS Classification of Hydrocarbons Physical properties Reactions & Mechanisms of Alkanes Structure & Conformation of Alkanes Conformation of Cycloalkanes

Hydrocarbons Hydrocarbons are molecules that are made of carbon and hvdrogen ONLY. TABLE 3-1 Hydrocarbon Classifications Compound Type Functional Group Example alkanes none(no double or triple bonds) CH3-CH2-CH3,propane alkenes CCdouble bond CH2=CH-CH3,propene alkynes -C=C-triple bond H-C=C-CH3,propyne CH,CH aromatics benzene ring ethylbenzene Copyright2010 Pearson Prentice Hall,Inc

Hydrocarbons are molecules that are made of carbon and hydrogen ONLY. Hydrocarbons

Common AlkyI Groups One carbon Two carbons Three carbons CH3 CH3一 CH3-CH2- CH3-CH2-CH2- CH3-CH- methyl group ethyl group propyl group isopropyl group (or“-propyl group") Four carbons CH3 CH3 CH3 CH3-CH2-CH2-CH2- CH3-CH-CH2一 CH3-CH2-CH- CH3-C- butyl group isobutyl group sec-butyl group (or“n-butyl group") CH3 tert-butyl group (or“t-butyl group") Copyright 2010 Pearson Prentice Hall,Inc

Common Alkyl Groups

CH CH CH: CH-CH, CH-CH, CH-CH-CH,CH; CH-CH-CH,CH, CH CH一CH, CH: CH-CH CH; CH; correct seven-carbon chain,bt ly three substituents seven-carbon chain,four substituents Copyright2010 Pearson Prentice Hall,Inc

Solved Problem 4-1 Give a systematic (IUPAC)name for the following compound. CH CH-CH, CH,CH CH,一CH-CH一CH,-CH-CH CH,C一CH CH; Copyright2010 Pearsan Prentice Hall Ins

Solved Problem 4-1 Give a systematic (IUPAC) name for the following compound

Solved Problem 4-1:Solution The longest carbon chain contains eight carbon atoms,so this compound is named as an octane.Numbering from left to right gives the first branch on C2;numbering from right to left gives the first branch on C3,so we number from left to right. CH 8 CH-CH, CH,CH CH, CH-4CH-CH,-CH-CH CH CH: CH ce Hall,Inc. 4-isopropyl-2,2,3,6-tetramethyloctane

The longest carbon chain contains eight carbon atoms, so this compound is named as an octane. Numbering from left to right gives the first branch on C2; numbering from right to left gives the first branch on C3, so we number from left to right. Solved Problem 4-1: Solution 4-isopropyl-2,2,3,6-tetramethyloctane

0不年 SEC 1 Physical Properties Solubility:hydrophobic Density:less than 1 g/mL Boiling points increase with increasing carbons (little less for branched chains). Melting points increase with increasing carbons(less for odd-number of carbons)

SEC 1 Physical Properties Solubility: hydrophobic Density: less than 1 g/mL Boiling points increase with increasing carbons (little less for branched chains). Melting points increase with increasing carbons (less for odd-number of carbons)

0t女车 Boiling Points of Alkanes Branched alkanes have less surface area contact,so weaker intermolecular forces. 400 300 CH3一(CH2)m-CH 200 uod n-alkanes 100 CH3 3um!oq 0 CH-(CH2)CH3 -100 isoalkanes CH3 -200 0 5 10 15 20 number of carbon atoms

Boiling Points of Alkanes Branched alkanes have less surface area contact, so weaker intermolecular forces