Fluoral polymerization

The polymerization of fluoral [61] has been studied in detail by Busfield [64]. It was found that fluoral polymerized very slowly in the presence of 2 mole % of formic acid but extremely quickly in the presence of as little as 0.2 mole % of a tertiary amine such as pyridine or trimethyl amine. Gasphase polymerization of fluoral was studied with trimethyl amine and it was found that the ceiling temperature was 73°C. The half life (50% conversion to polymer) of fluoral polymerization with formic acid was 12 h but for pyridine or trimethyl amine it was about 30 sec. 

Polymerizations of halo aldehydes are often discussed separately from those of the aliphatic higher polyaldehydes [61]. Chloral and fluoral have... 

The simplest fluorinated aldehydes, fluoral, known to undergo polymerization instantaneously in the presence of amines, failed to undergo effieient MBH reaction with ethyl acrylate and acrylonitrile. However, pentafluoro-benzaldehyde could provide good yields of MBH adduct 135. Alternatively, unsubstituted and -substituted [a-(ethoxycarbonyl)vinyl] aluminium 136 reacts with perfluoroalkyl and aryl aldehydes 134 to provide the fluorinated MBH adducts 135 in good to excellent yields (Scheme 1.59). °... 

Encouraged by the success with fluoral, fluoroketones have also been investigated systematically in the MBH reaction. Since 1,1,1-trifluoroacetone is known to trimerize in the presence of amines, lower yields of MBH adducts were obtained at lower temperature when treated with acrolein and acrylonitrile. With methyl acrylate and MVK, however, only a polymeric material was isolated under the MBH reaction conditions. 

It has earlier been established that chloral can only be polymerized to crystalline, apparently isotactic polymer, no soluble fraction, even of low molecular weight, has ever been observed. ( ) Fluoral has been known to exist also in a soluble form.(9) It has become very desirable to establish clearly the space filling size of trihalomethy1 sustituent of the per-haloacetaldehyde (which after polymerization becomes the side group of the polyacetal chain) that is necessary to form isotactic polymer and isotactic polymer only. 

Aldehydes, both aliphatic and perhaloacetaldehyf des polymerize by cationic and anionic mechanisms (Eqn. I), and all the various intiators were investigated in this work. Fluoral has been reported to have also been polymerized by radical initiators (10). Since our polymerizations could be readily accomplished with well established initiators, it was not found necessary to study other possible ways of initiation. 

Chloral was known to give only insoluble, presumably isotactic polymer, fluoral could be polymerized to insoluble and soluble presumable atactic polymer. 

Fluoral was prepared from the commercially available fluoral hydrate by dehydration with sulfuric acid and ultimately with polymerized with... 

MBH Reaction of Perfluoro-aliphatic Aldehydes. Fluoral is known to polymerize in the presence of amines (Scheme 4) (16), However, we tested whether the polymerization is favored in the presence of activated olefms. 

---