论文部分内容阅读
正构烷的红外光谱彼此十分接近,尤其在碳数较高时很难鉴别。本文根据它们的结构特点和CH_2与CH_3基变形振动吸收位置以及吸收率恒定的特征,提出了利用722厘米~(-1)和1380厘米~(-1)两吸收带光密度的比值同相应基团CH_2和CH_3数目的比值之间的线性关系,进行结构基团的定量测定方法,郎比值法。考察了光谱狭缝宽度的影响。这个方法毋需准确计量浓度和繁杂计算,可以简便准确地鉴定单纯正构烷烃的碳数n,或混合物的平均基团含量。C_6—C_(22)间11个标定化合物的分析结果表明,碳数n的测定偏差一般不超过半个碳原子,CH_3%偏差小于1%。同平均吸收卒法比较,比值法比较简单准确。
The infrared spectra of n-alkanes are very close to each other, especially when carbon numbers are high. In this paper, based on their structural characteristics and the locations of the vibrational absorption sites and the constant absorption rate of CH_2 and CH_3 groups, the authors propose the use of the same optical density of the absorption bands at 722 cm -1 and 1380 cm -1 The linear relationship between the number of groups CH_2 and CH_3, the quantitative determination of structural groups, Lang ratio method. The effect of spectral slit width was examined. This method allows simple and accurate identification of carbon numbers n of pure n-alkanes, or average radical content of mixtures, without the need to accurately measure concentrations and calculations. Analysis of 11 calibration compounds between C_6-C_ (22) showed that the deviation of carbon number n was not more than half a carbon atom and the deviation of CH_3% was less than 1%. Compared with the average absorption method, the ratio method is relatively simple and accurate.