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以26型氟橡胶氧化降解而制备的液体端羧基氟橡胶为原料,通过官能团转化法合成了液体端酰氯基氟橡胶。选用二氯亚砜(SOCl_2)和草酰氯(COCl)_2为酰化试剂,吡啶、N,N-二甲基甲酰胺(DMF)和三乙胺(TEA)为催化剂,对反应条件、催化剂以及酰化试剂的种类和用量等因素进行了系统研究。采用红外(FTIR)和氟谱核磁(~(19)F-NMR)对其结构、端基转化率进行了分析和测试。结果表明,两种酰化试剂均可实现液体端酰氯基氟橡胶的合成,产物FTIR谱图中1 795 cm~(-1)处出现了—COCl伸缩振动峰;~(19)F-NMR谱图中-102.54×10~(-6)处出现了—CF_2COCl的特征峰。当SOCl_2为酰化试剂时,反应温度、催化剂种类和用量对端基转化率影响较大,反应时间和SOCl2用量对端基转化率影响较小,羧基转化率最高可达86%;当(COCl)_2为酰化试剂时,反应温度、催化剂种类及其用量,以及(COCl)_2用量对端基转化率影响较大,反应时间对端基转化率影响较小,由于反应中会伴随Vilsmeier-Haack反应的发生,所以羧基转化率偏低为70%。
Hydroxyl-terminated fluorocarbon rubber was synthesized by the functional group conversion method from the liquid carboxyl-terminated fluororubber prepared by the oxidative degradation of 26-type fluororubber. The reaction conditions, the catalyst and the reaction conditions were optimized by using SOCl_2 and COCl_2 as the acylation reagent, pyridine, N, N-dimethylformamide (DMF) and triethylamine (TEA) The type and amount of acylation reagents and other factors were systematically studied. The structure and end group conversion were analyzed and tested by FTIR and ~ (19) F NMR. The results showed that both of the acylation reagents could be used to synthesize liquid chlorofluorocarbons. The FTIR spectrum of the product exhibited a -COCl stretching vibration peak at 1 795 cm -1. The ~ (19) F-NMR spectrum In the figure, the characteristic peak of -CF_2COCl appears at -102.54 × 10 -6. When SOCl_2 is the acylation reagent, the reaction temperature, catalyst type and amount have a great influence on the end group conversion. The reaction time and the amount of SOCl2 have little effect on the end group conversion, and the highest conversion of carboxyl group can reach 86%. When (COCl ) _2 for the acylation reagent, the reaction temperature, the type of catalyst and its dosage, and the amount of (COCl) _2 greatly affect the end group conversion, the reaction time on the end group conversion is less affected, as the reaction will be accompanied by Vilsmeier- Haack reaction occurred, so the carboxyl conversion rate is as low as 70%.