交联聚苯乙烯树脂固载甲酰基的微波辅助还原

在微波照射的相转移催化(MI-PTC)条件下,3种甲酰基功能化的交联聚苯乙烯树脂——对甲酰基苯氧基甲基树脂、对甲酰基-2-甲氧基苯氧基甲基树脂和对甲酰基-3-甲氧基苯氧基甲基树脂固载的甲酰基被NaBH4还原,得到相应的3种苄羟基功能化的树脂——Wang树脂、Sasrin树脂和新型的对苄羟基-3-甲氧基苯氧基甲基树脂.考察了溶剂、相转移催化剂等因素对反应的影响,优化的反应介质为THF/H2O混合溶剂,相转移催化剂为苄基三羟乙基氯化铵(BTHAC).然而,在传统加热和微波辐射条件下,最有效混合溶剂的配比有所不同.在水浴加热条件下,最有效的反应溶剂为12 mL THF+3 mL H2O;而在微波加热的条件下,最有效的反应溶剂却是3 mL THF+12 mL H2O.在优化的溶剂、催化剂条件下,微波功率为60 W时,高分子固载的甲酰基30 min之内几乎被定量地还原成羟基.与传统加热方式比较,MI-PTC还原聚苯乙烯固载甲酰基可以大大缩短反应时间,提高反应效率,是一种进行高分子化合物官能团转化的良好方法.

MICROWAVE-ASSISTED REDUCTION OF FORMYL SUPPORTED BY CROSS-LINKING POLYSTYRENE RESIN

Three cross-linking polystyrene resins functionalized with formylgroups,pformylphenoxymethyl,p-formyl-2-methoxyphenoxymethyl and p-formyl-3-methoxyphenoxymethyl were reduced by NaBH_4 under phase transfer catalytic conditions coupling with microwave irradiation(MI-PTC),and three benzylhydroxyl resins,the Wang resin,Sasrin resin and a novel p-benzylhydroxyl-3-methoxyphenoxymethyl resin were correspondingly obtained.The preparations of these resins were carried out under heating in water batch and microwave irradiation.The reaction monitoring was performed by FTIR,and the contents of hydroxyl groups of target resins were determined by nitrogen element analysis involving derivative reaction of 3,5-dinitrobenzoyl chloride.The influence factors such as solvent and phase-transfer catalyst were experimentally investigated.The optimized solvent was THF/H_2O among DMF,ethanol,THF,and THF/H_2O,and the optimized phase-transfer catalyst was benzyltrihydroxylethyl ammonium chloride(BTHAC) among BTHAC,PEG-400,cetyl trimethyl ammonium chloride(CTMAC),tetrabutylammonium chloride(TBAC).However,the mixture ratio of the optimized solvent was different for reations with traditional heating and microwave irradiation.Under heating in water batch,the optimized solvent was 12 mL THF 3 mL H_2O,while that was 3 mL THF 12 mL H_2O under microwave heating.The polymer-supported formyl groups were almost quantificationally converted into hydroxyl groups in 30 minutes under the optimized conditions and 60 W power microwave input,while under the traditional heating the reaction time exceeded 24 h and the conversion extent of formyl groups was somewhat less.Compared with that of conventional heating,the reduction of formyl supported by crosslinking polystyrene under MI-PTC by NaBH_4 was a good method with short reaction time and improved conversion.