【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。更多还原

【Abstract】 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（δ_c）with long chain alkyl and methyl substitutes can be achieved with δ_c=δ_mono+∑Z_i,where Z_i（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_monois individual chemical shift of carbon in mono alkylbenzene.Z_s,Z_o,Z_m and Z_p are developed as+9.13,+0.63,-0.23 and -3.15 respectively. For carbon in long chain alkyl at α-position of aromatic ring branching,Z introduced by methyl substitution either in m-position(Z_mα)or p-position(Z_mβ)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(Z_pα)or p-position(Z_pβ)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.更多还原