Three cross-linking polystyrene resins functionalized with formylgroups

p-formylphenoxymethyl

p-formyl-2-methoxyphenoxymethyl and p-formyl-3-methoxyphenoxymethyl were reduced by NaBH4 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/H2O among DMF

ethanol

THF

and THF/H2O

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 H2O

while that was 3 mL THF + 12 mL H2O 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 cross linking polystyrene under MI-PTC by NaBH4 was a good method with short reaction time and improved conversion.