Research Of Estimating Methods Based On Elements And Chemical Bonds For The Normal Boiling Point Of Organic Compounds

Data concerning the normal boiling point of organic compounds are very important in chemical dustries, but are not available when they need. It is difficult to measure all of them as the need arise. So the idea of estimation is proposed.To obtain the properties of pure compounds, simple group contribution methods, which can provide the important advantage of quick estimation are widely used at early stage. However, many of these methods are of questionable accuracy.To overcome this limitation, complex group contribution methods have been introduced into the relevant research.In this paper, the methods to estimate the normal boiling point in the literature were summarized. Then the widely used methods with high estimation accuracy were slected, which include the Joback method, modified Joback method, C-G method, M-P method and Xuwen method. On the basis of 4,068 kinds of credible experimental data, comparison and evaluation of these five methods was presented. The results show that CG2 method is convenient to use and can differentiate some isomers. It is the best method with high estimation accuracy. Especially for alkane, chloride derivative, bromide derivative, alicyclic hydrocarbon, aromatic hydrocarbon and nitrogen- containing compounds, the estimation accuracy of CG2 is the highest. For iodine derivative, the estimation accuracy of MP2 is the highest. For fluoride derivative, oxygenated hydrocarbon and sulfur- containing compounds, the estimation accuracy of MP4 is the highest. For alkene and alkyne, the estimation accuracy of XuWen is the highest. The modified Joback method does not exert obvious effects on the Joback method and needs further improvements.According to molecular structure theory, a new method based on elements and...