双取代烷基苯的核磁共振碳谱分析  

Analysis of Dialkyl Benzene by Means of ^(13)C NMR

作　　者：彭朴[1] 葸雷[1] 刘冬云[1] 黄蔚霞[1] 

机构地区：[1]中国石油化工股份有限公司石油化工科学研究院石油化工催化材料与反应工程国家重点实验室,北京100083

出　　处：《石油化工》2008年第9期947-954,共8页Petrochemical Technology

摘　　要：在导出双取代烷基苯的化学位移加和规律的基础上,归属了烷基化产物长直链烷基和甲基双取代烷基苯的核磁共振碳谱。以单取代的长直链烷基苯为基础,根据δ_C=δ_(mono)+∑Z_i(δ_C 为双取代烷基苯中各碳原子的化学位移;δ_(mono)为单取代长直链烷基苯中各碳原子的化学位移;Z_i为化学位移增量)可计算出双取代烷基苯中各碳原子的化学位移。对于芳碳原子,甲基收代位的碳和甲基取代位的邻位、间位、对位碳的化学位移增量分别为+9.13,+0.63,-0.23,-3.15。对于长直链烷基碳原子,当两个烷基处于苯环的间位时,甲基取代引起的α位和β位烷基碳的化学位移增量分别为-0.04和+0.08;当两个烷基处于苯环的对化时,甲基取代引起的α位和β位的烷基碳的化学位移增量为-0.43和+0.01。烷基化产物中未见邻位双取代物。在谱峰完全归属的基础上,用7种方法测定了烷基取代位置异构体或芳环取代位置异构体的组成。The dialkyl benzenes were prepared by Friedel-Crafts reaction and characterized by ^13C NMR spectroscopy. Chemical shift increments（Z） for assignments of specific carbon atoms in dialkyl benzene were detailed aiming at developing a rapid and nondestructive method without pre-separation. The prediction of carbon chemical shifts of dialkyl benzene （ δc ） with long chain alkyl and methyl substitutes can be achieved with δc = δ ＋ ∑Zi, where Zi （ i = methyl substitution position （ s）, ortho （ o ）, meta （ m ） ,para （p） position of methyl substitution） is chemical shift increments of aromatic carbon introduced by methyl substitution, δ is individual chemical shift of carbon in mono alkylbenzene. Zs,Zo,Zm and Zp are developed as ＋ 9.13, ＋ 0.63, - 0.23 and - 3. 15 respectively. For carbon in long chain alkyl at a-position of aromatic ring branching, Z introduced by methyl substitution either in m-position （ Zmα ） or p-position （ Zmβ ） are developed as -0.04 and ＋ 0.08 whereas for carbon in long chain alkyl at β-position of aromatic ring branching, Z introduced by methyl substitution either in m-position （Zpα） or p-position （ Zpβ ） are developed as - 0.43 and ＋ 0.01. The 7 methods to determine composition of different isomers of dialkyl benzene prepared by Frediel-Crafts alkylation were developed based on detailed assignments of their ^13C NMR spectra.

关 键 词：核磁共振碳谱 化学位移加和规律 烷基苯 烷基甲苯 烷基化反应 

分 类 号：TQ207.4[化学工程—有机化工]