大学有机化学第二章烷烃

1、大学有机化学第二章烷烃5) Many insect sex attractants have been synthesized and are used to lure insects into traps as a means of insect control.HH3C(H2C)7H(CH2)12CH34) Muscalure is the sex attractant of the common housefly() (Musca domestica).chain (链烃)Chapter 2 Alkaneshydrocarbons(碳氢化合物烃)aliphatic (脂肪烃) satur

2、ated aliphatic (饱和脂肪烃)alkanes(烷烃)unsaturated aliphatic alkenes(烯烃)alkynes (炔烃)cyclic (环烃)alicyclic (脂环烃)aromatic (芳香烃)1. Homologous series and constitutional isomers of alkanes (烷烃的同系列与构造异构)C CH H4 4, , C C2 2H H6 6, , C C3 3H H8 8, , . . . ., , C Cn nH H2 2n n+ +2 21.1 Homologous series - -C CH H 2

3、 2- -HHHHHybridization? Bonding?1.2 Structure1.3 Constitutional isomers（构造异构体）structureconstitution(构造)configuration(构型)conformation(构象)Order of atomic connections that defines a molecule Arrangement of atoms that characterizes a particular stereoisomerDifferent arrangements of atoms that can be con

4、verted into one another by rotation about single bondsC CH H4 4HHHHCHHHHconstitutional formulaconfigurational formulaC C2 2H H6 6CC CH HH HH HH HH HH HC CH H3 3- -C CH H3 3C C3 3H H8 8CC CH HH HH HH HH HC CH HH HH HC CH H3 3- -C CH H2 2- -C CH H3 3C C4 4H H1 10 0C CH H3 3- -C CH H2 2- -C CH H2 2- -C

5、 CH H3 3C CH H2 2- -C CH H- -C CH H3 3C CH H3 3constitutional isomers (构造异构体)C C5 5H H1 12 2C CH H3 3- -C CH H2 2- -C CH H2 2- -C CH H2 2- -C CH H3 3C CH H2 2- -C CH H- -C CH H2 2- -C CH H3 3C CH H3 3C CH H2 2- -C C- -C CH H3 3C CH H3 3C CH H3 3C CH H3 3- -C CH H2 2- -C CH H2 2- -C CH H2 2- -C CH H2

6、 2- -C CH H3 3C C6 6H H1 14 4C CH H3 3- -C CH H- -C CH H2 2- -C CH H2 2- -C CH H3 3C CH H3 3C CH H3 3- -C CH H2 2- -C CH H- -C CH H2 2- -C CH H3 3C CH H3 3C CH H2 2- -C C- -C CH H2 2- -C CH H3 3C CH H3 3C CH H3 3C CH H2 2- -C CH H- -C CH H- -C CH H3 3C CH H3 3C CH H3 31.4 Classes of carbon atoms and

7、 hydrogen atoms(碳原子和氢原子的类型)C CH H3 3C CC CH H3 3C CH H3 3C CH HC CH H3 3H H2 2C CC CH H3 31o2o3o4oprimary (伯)secondary (仲)tertiary (叔)quarternary (季)1o1o1o1o1o2o3o4o2. Nomenclature of alkanes(烷烃的命名)2.1 Common names(普通命名法)methane甲烷 ethane乙烷 propane丙烷 n-butane正丁烷n-pentane正戊烷 n-hexane正己烷 n-heptane正庚烷n-

8、octane正辛烷 n-nonane正壬烷 n-decane正癸烷 n-undecane正十一烷.straight chain(直链)Branched chain(支链) ?C CH H2 2- -C CH H- -C CH H3 3C CH H3 3isobutane异丁烷C CH H2 2- -C CH H- -C CH H2 2- -C CH H3 3C CH H3 3isopentane异戊烷C CH H2 2- -C C- -C CH H3 3C CH H3 3C CH H3 3neopentane新戊烷C C6 6H H1 14 4 5 constitutional isomers

9、?IUPAC ( international union of pure and applied chemistry) namesSystematic names (系统命名法)2.2 Systematic names(系统命名法)2.2.1 Fundamental knowledge (基础知识) methane甲烷 ethane乙烷 propane丙烷 n-butane正丁烷n-pentane正戊烷 n-hexane正己烷 n-heptane正庚烷n-octane正辛烷 n-nonane正壬烷 n-decane正癸烷 n-undecane正十一烷.straight chain2.2.2 A

10、lkyl groups(烷基)-ane -yl (alkane alkyl)Methyl甲基 Ethyl乙基n-Butyl正丁基n-Propyl正丙基CH3CH2CH2CH2CH3CH3CH2CH3CH2CH2H3CCHCH3isopropyl异丙基1-methylethyl1-甲基乙基i-PrCH3CHCH2CH3 isobutyl异丁基2-methylpropyl2-甲基丙基i-BuCH3CCH3CH3 tert-butyl叔丁基1,1-dimethylethyl1,1-二甲基乙基t-BuH3CH2C CHCH3 sec-butyl仲丁基1-methylpropyl1-甲基丙基(CH3)3

11、CCH2-s-Buneopentyl新戊基2,2-dimethylpropyl2,2-二甲基丙基CH3CH2.CH-CH3(CH3)2CH.CH2-CH3CH2.C-CH3CH3仲某基异某基叔某基CH3CH2CHCH2CCH2CH2CH2CH3CH3CH3CH2CH2CHCH2CH2CH3CH32.2.3 Nomenclature(命名)1)Select as the parent structure the longest continuous chain.2)Number the carbon to which the alkyl group is attached.3)Name5-but

12、yl-3,5,8-trimethylundecane3,5,8-三甲基-5-丁基十一烷CH3CH2CH2CHCH2CHCH2CH2CH2CH3CH3CH2CH34-甲基-6-乙基癸烷6-ethyl-4-methyldecanea system of rules based on atomic number. Sequence rule(次序规则)CH3CH2CH2CHCH2CH2CH2CHCH2CH2CH3CH3CH(CH3)24-甲基-8-异丙基十一烷4-isopropyl-8-methylun-decane-H（氢）-D（氘）-CH3（甲基）-CH2CH3（乙基）-CH2CH2CH3（丙基

13、）-CH2C6H5（苯甲基、苄基）-CH(CH3)2（异丙基）-CH=CH2（乙烯基）-C(CH3)3（叔丁基）-C6H5（苯基）-CCH（乙炔基）-CH2NH2（氨甲基） -CN（氰基）-CH2OH（羟甲基）-CHO（醛基、甲酰基）-COCH3（乙酰基）-COOH（羧基）-COOCH3（甲氧羰基、甲酯基）-NH2（氨基）-NHCHO（甲酰氨基）-NHCOCH3（乙酰氨基）-N(CH3)2（二甲氨基） -N+N（重氮基）-NO（亚硝基）-NO2（硝基）-OH（羟基）-OCH3（甲氧基）-OCOH（甲酰氧基）-OCOCH3（乙酰氧基）-F（氟）-SH（巯基） -SO3H（磺酸基）-Cl（氯）-B

14、r（溴） 2 1 CH3 Ar ，CH2=CH Configuration (构型): the CH3 radical is planar (sp2 hybridized carbon)6.3 Autoxidation (自动氧化)ROORHROOROOHInitiatingPropagatingOOHR+O2R+O2+ RRHR-H Reactivity (活性): 3 2 1 The OO bond of an alkyl hydroperoxide is quite weak, and it canbreak and produce radicals that can initiate

15、other chains: ROOH RO + OHBenzoyl Peroxide (过氧化苯甲酰)Benzoyl peroxide is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link.PhCOOOCOPhThe oxygen-oxygen bond in peroxides is weak. Thus benzoyl peroxide readily undergoes homolysis, forming free radic

16、als: (C6H5CO)2O2 2 C6H5COOBenzoyl peroxide is used as a radical initiator to induce polymerizations. Other major applications include treating acne(痤疮,粉刺), dyeing hair, whitening teeth, and brightening flour.The FDA (the Food and Drug Administration) eventually classified benzoyl peroxide as “safety

17、 unknown”.especially susceptible to abstraction by O2(CH2)7CO2RHHCH3(CH2)4HHCHHradical (Lin) autoxidation hydroperoxide rancidity (酸败)Autoxidation occurs in the body which may cause irreversible damage. linoleic acid (亚油酸) (as an ester)Antioxidants (抗氧剂抗氧剂)Autoxidation is inhibited by antioxidants，w

18、hich can rapidly “trap” peroxyl radicals by reacting with them to give stabilized radicals that do not continue the chain.Vitamin E Vitamin C BHT : added to foods to prevent autoxidation There are two reasons why some radicals are more persistent than others:(1) steric hindrance;(2) electronic stabi

19、lization.Many of the molecules that make up the structure of human tissue are susceptible to homolysis in intense light, and the body makes use of sophisticated chemistry to protect itself from the action of the reactive radical products. Vitamin E plays an important role in the taming of these radi

20、cals: abstraction of H from the phenolic hydroxyl group produces a relatively stable radical that does no further damage.Polydimethylsiloxane(PDMS, 聚二甲基硅氧烷)PDMS is the most widely used organic polymer, and is particularly known for its unusual flow properties. Its applications range from contact len

21、ses (隐形眼镜) to elastomers (弹性体)。According to the Handbook of Food Additives, PDMS is a suspected carcinogen (致癌物) and an established mutagen (诱变剂).Bet you never thought those were in your chicken McNuggets!According to A Consumers Dictionary of Food Additives, TBHQ can comprise no more than 0.02 perc

22、ent of the oil in a nugget.Ingesting a single gram of TBHQ can cause “nausea, vomiting, ringing in the ears, delirium (精神错乱), a sense of suffocation, and collapse.” Ingesting five grams of TBHQ can kill.tert-Butylhydroquinone (TBHQ, 特丁基对苯二酚 ) 6.4 Nitration(硝化) (Substitution)6.5 Sulfonation(磺化) (Subs

23、titution)HOSO3H400oCCH3CH2SO3HCH3CH3Reactivity: F2Cl2Br2I2Fluorine is an extremely aggressive oxidizing agent, and its reaction with alkanes is strongly exothermic (放热的) and difficult to control. Chlorination of alkanes is less exothermic than fluorination, and bromination less exothermic than chlor

24、ination. Iodine is unique among the halogens in that its reaction with alkanes is endothermic (吸热的).CH3CH2CH3HONO2420oCCH3CH2CH2NO2+ CH3CHCH3NO2(major)+ CH3CH2NO2CH3NO26.6 Halogenation(卤化) (Substitution)6.6.1 Chlorination of methane(甲烷的氯化)H CHHHH CClHClH CClClClClCClClClH CHHCl+H ClCl2heatorlightMechanism(机理)(链引发)(链增长)（c）Chain-terminating steps(链终止)CH4Cl+Cl.H.CH3Cl.Cl.CH3CH3Cl2HCl+CH3ClCl+transition statetransition stateEact1Eact26.6.2 Halogenation of higher alkanes(高级烷烃的卤化)CH3CH2CH3CH3CH2CH