Analysis Of Three Methods For Preparing Parylene F

Among the polymer coating materials Parylene powder family, Parylene F has the best thermal stability. It has good high temperature resistance and ultraviolet resistance, good wave permeability, and low dielectric constant, it is very suitable for use as a protective material for high-frequency microwave devices, and has broad application prospects. The method for preparing Parylene F has an important influence on the quality and price of Parylene F. The development of a cost-effective synthetic process can expand the application of parylene powder. This article introduces three synthetic processes of parylene F.

The first method：adding 2,3,5,6-tetrafluoro-p-methylbenzyl chloride and a solvent into a reactor, and maintaining the temperature of the reactor to be within a range of 20-40 ° C; slowly dropwise adding a trimethylamine solution, and then carrying out a reaction for 4-6h; after that, adding a solvent, a polymerization inhibitor and a catalyst into reaction liquid, heating up to 90-120 ° C, then dropwise adding 40% sodium hydroxide solution, carrying out a reaction under the condition of heat preservation, and separating out part of water; continuously stirring for reacting for 8-12h, slightly cooling, then adding right amount of water into the reactor, and stirring for about half an hour; then, standing, separating out a saline layer, and removing toluene in an organic layer to obtain a crude product;  Finally, after decoloring, recrystallizing, filtering, and drying to obtain a finished product of Parylene F .

This method has mild reaction conditions, good selectivity, high yield, and is environmentally friendly, but the operation is more complicated and the reaction time is long.

The Second method: in a reasonable working environment, preparing 4-methyl tetrafluoroe benzyl chloride from 4-methyl tetrafluoroe phemethylol and thionyl chloride, preparing 4-methyl tetrafluoroe quarternary ammonium salt from 4-methyl tetrafluoroe benzyl chloride and a methylamine water solution, and preparing parylene F from the 4-methyl tetrafluoroe quarternary ammonium salt and a methylbenzene system solution.

The preparation method of parylene F powder has the advantages of mild reaction, simple raw material acquisition and relatively low price, but requires three chemical reactions and many reaction steps.

The third method: using 2,3,5,6-tetrafluoro-p-dichloromethylbenzene as raw material, first add zinc powder, solvent, polymerization inhibitor and catalyst to the reactor, stir and heat evenly, and keep the temperature at 50 ～ 80 ℃; Then dissolve 2,3,5,6-tetrafluoro-p-dichloromethylbenzene with a solvent and drop it into the reactor to obtain the reaction solution, then filter and distill the reaction solution to obtain the crude product ; Finally, decolorize and purify the crude Parylene F , and then dry to obtain the finished Parylene F.

This method can synthesize the target product through a one-step reaction. The operation is simple, the process is safe and stable, the yield is high, and the raw material cost is controllable. The disadvantage is that the raw material has low toxicity.

Related link: Parylene F

references:

1. Synthesis method of octafluoro-paracyclophane . CN106977364A

2.Method for preparing parylene F. CN107216232A

3.Octafluorofluoro-cyclic di-p-xylyene and synthesis method thereof. CN109232168A