Aromaticityhydrocarbons aliphaticaromaticalkanes alkenes .ppt
《Aromaticityhydrocarbons aliphaticaromaticalkanes alkenes .ppt》由会员分享,可在线阅读,更多相关《Aromaticityhydrocarbons aliphaticaromaticalkanes alkenes .ppt(33页珍藏版)》请在麦多课文档分享上搜索。
1、Aromaticityhydrocarbonsaliphatic aromaticalkanes alkenes alkynes,Aliphatic compounds: open-chain compounds and ring compounds that are chemically similar to open-chain compounds. Alkanes, alkenes, alkynes, dienes, alicyclics, etc.Aromatic compounds: unsaturated ring compounds that are far more stabl
2、e than they should be and resist the addition reactions typical of unsaturated aliphatic compounds. Benzene and related compounds.,Benzene. This aromatic hydrocarbon was first discovered in 1825 but its structure was not generally agreed upon until 1946.Facts about benzene: Formula = C6H6 Isomer num
3、ber:one monosubstituted isomer C6H5Y knownthree disubstituted isomers C6H4Y2 known Benzene resists addition reaction, undergoes substitution reactions. Heats of hydrogenation and combustion are far lower than they should be. From X-ray, all of the CC bonds in benzene are the same length and intermed
4、iate in length between single and double bonds.,a) Formula = C6H6 Max. number of Hs for 6-carbons = 14. Benzene only has 6 hydrogens. Given one degree of unsaturation (double bond or ring) for every two missing hydrogens less than the maximum, benzene has 4 degrees of unsaturation; that is four comb
5、inations of pi-bonds and rings.CH3CC-CCCH3 HCC-CC-CH2CH3HCCCH2CCCH3 HCCCH2CH2CCH,CH3 HCCCHCCH CH2=CHCCCH=CH2CH2=CHCH=CHCCH CH2=C=CHCH2CCHCH3 CH2=C=CHCCCH3 CH2=C=CCCHCH=CH2 CH2=C=CHCH=C=CH2 CH2=CCCH CH3CH=C=CHCCH,CH2,H2C,CH2,=C=C=CH2,=C=CH2,CH2,CH2,CH2,=CH2,HC2=,=CH2,Which of these structures is benz
6、ene?,Isomer number. There is only one monosubstituted benzene of any type: only one bromobenzene C6H5Br, only one nitrobenzene C6H5NO2, etc.CH3CC-CCCH3 HCC-CC-CH2CH3one possible three possiblesHCCCH2CCCH3 HCCCH2CH2CCHthree possible two possible,CH3 HCCCHCCH CH2=CHCCCH=CH2three two +CH2=CHCH=CHCCH CH
7、2=C=CHCH2CCHfive + four +CH3 CH2=C=CHCCCH3 CH2=C=CCCHthree + three +CH=CH2 CH2=C=CHCH=C=CH2 CH2=Cfour + CCH four +CH3CH=C=CHCCH four +,CH2,H2C,CH2,=C=C=CH2,=C=CH2,CH2,CH2,CH2,=CH2,HC2=,one possible,two,three +,two +,two,=CH2,three,one,two,CH3CC-CCCH3,There are three disubstituted benzenes of any typ
8、e: three dibromobenzenes C6H4Br2, etc.,CH2,CH2,CH2,two possible,four,four,No classical valence bond structure for C6H6 correctly explains the existence of only one monosubstituted benzene and three disubstituted benzenes. Kekul (1890) proposed that the following were in rapid equilibrium:,If benzene
9、 is 1,3,5-cyclohexatriene as Kekul proposed, what should its chemistry be? Alkenes, dienes, cyclcoalkenes, etc. typically give addition reactions with electrophiles. But benzene doesnt undergo the reactions typical of unsaturated hydrocarbons!,Reagent Cyclohexene Benzene,Benzene + 3 H2, Ni, room tem
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
2000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- AROMATICITYHYDROCARBONSALIPHATICAROMATICALKANESALKENESPPT

链接地址:http://www.mydoc123.com/p-378570.html