Quality of the THF Input

Because of the ease with which THF forms peroxides, it is normally shipped and stored in the presence of a stabilizer such as 2,6-di-t-butyl-4-methylphenol (butylated hydroxytoluene, BHT). In addition, THF readily absorbs water and oxygen. Inasmuch as these impurities are detrimental to polymerization, it is imperative to purify the THF before it can be used as a polymerization monomer. 

It is strongly recommended that the THF first be checked for the amount of peroxide or hydroperoxide before any further purification is attempted. If more than 0.1 % is found, the peroxide must be decomposed. This can be done by agitating with flake caustic soda. It has also been suggested to effect the deperoxidation by means of self-indicating molecular sieves [95], but inasmuch as this must result in a peroxide enrichment in the molecular sieve, this procedure is viewed as a source of danger which has not been sufficiently investigated so far. 

There is an azeotrope at 18.3 % water by mole (5.3 % water by weight). Thus, if the water content is below 5.3 % by weight, which is usually the case, most of the water can be removed by azeotropic distillation, as in the case of furfural. To remove the last traces of water, the best procedures are the following  

The applications of PTHF, in the form of PTMEG (i.e. with OH end groups), lies in the manufacture of elastomers. On an atomic scale, the PTHF chain is not straight but consists of straight sections joined by angled links (ether bridges) in between as shown below  

The C - N - C bond angle of 109 ° [96] is seen to add to the elasticity of the chain. Linkage of such structures with hydrazine leads to fibers as they are used for stretch pants . 

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