Research On The Synthesis Process Of1,1,1,3,3-Pentachloropropane

1,1,1,3,3-pentafluoropropane is a highly effective polyurethane blowing agent, and it does no damage to the ozone layer. In recent years, more and more attention has been paid to the synthesis process of1,1,1,3,3-pentachloropropane, which is the key intermediate of1,1,1,3,3-pentafluoropropane.1,1,1,3,3-pentachloropropane was prepared by radical addition between carbon tetrachloride and vinyl chloride in the presence of iron powder and dibutyl phosphate. The proper reaction condition was as follows:material mole ratio n (CCl4):n (VnCl)=1:0.1～0.4, reaction temperature115℃, reaction time4～5h, the amount of iron powder was0.6-0.9%(based on total mass material). Dibutyl phosphate was selected as co-catalyst, and its molar weight was equal to that of iron powder. The yield of1,1,1,3,3-pentachloropropane was87.6%and the purity of product was99.8%. This synthetic method has not yet been reported.Then, this dissertation described a quantitative analysis method of1,1,1,3,3-pentachloropropane by gas chromatography, the internal standard sample is1,3-dichlorobenzene. A new manipulation of this gas chromatography internal standard method was established on the basis of the detected components were liquid. This new method was much more simple, rapid and accurate than the traditional one.Thirdly, the effects of factors such as temperature, pressure, iron powder, tributyl phosphate on the thermal stability of1,1,1,3,3-pentachloropropane were examined. The results showed:the degradation rate of1,1,1,3,3-pentachloropropane will increase with the increase of temperature, but decrease with the increase of pressure; Adding iron powder will exacebate the thermal decomposition reaction of1,1,1,3,3-pentachloropropane; Meanwhile, adding tributyl phosphate could effectively inhibit this thermal decomposition reaction. Therefore, tributyl phosphate was an effective dehydrochlorination stabilizer for1,1,1,3,3-pentachloropropane.Meanwhile, the telomerization reaction kinetics of the synthesis of1,1,1,3,3-pentachloropropane was studied. It was found that this telomerization reaction was of first order in the range of80～115℃, the apparent activation energy was69.15kJ·mol-1, the pre-exponential factor was4.17×107, and the apparent kinetic equation was obtained.Finally, this dissertation presented the possible mechanisms of this telomerization reaction under two different kinds of conditions. This reaction followed a free radical reaction mechanism in the absence of catalyst, but followed a non-chain redox mechanism in the presence of catalyst. In addition, the reaction process of iron powder transforming into ferric chloride and the formation mechanisms of [FeCl2-DBP] coordinate complex were first presented.