Ethylene Glycol related reagents

Disulfides were shown to be intermediates in the iodine oxidation of 1,3-butadiene-l-thiols and related compounds to form thiophenes (56JOC39). Several simple disulfides were converted to thiophene derivatives under these same conditions (64JOC2372). For example, bis(2-biphenyl) disulfide (13) produced dibenzothiophene (14) in 64% yield when heated with iodine in ethylene glycol for one hour. Treatment of (13) in benzene with aluminum bromide gave (14) in 76% theoretical yield, with an equivalent amount of the thiol, 2-biphenylthiol (62JOC4111). Thus the iodine reagent is more efficient, since it oxidizes the mercaptan, formed by the Friedel-Crafts reaction of disulfide on the adjacent aromatic ring, to disulfide for further reaction, and also serves as a catalyst for the initial reaction. 

First, there is the coenzyme B -dependent (Chapter 12 and 14) catalyzed dehydration of 1,2,3-trihydroxypropane (glycerol) to 3-hydroxypropanal (Scheme 8.73) by what is apparently a free radical reaction. Such a free radical process is apparently related to the similar oxidation of 1,2-hydroxyethane (ethylene glycol) by iron(ll) in the presence of hydrogen peroxide (the Fenton reagent), also shown as part of Scheme 8.73. 

Related Reagents. 3-Bromo-1,2-propanediol 2,3-Butane-diol Ethylene Glycol (2R,4/ )-2,4-Pentanediol 1,3-... 

Among the best-known nonderivatizing solvent systems is a combination between copper, alkali, and ammonia termed Schweizer s reagent. Solutions of cuprammonium hydroxide have been used for both analytical and industrial cellulose dissolution. Regenerated fibers with silk-like appearance and dialysis membrane have been (and partially continue to be) industrial products on the basis of cellulose dissolution in cuprammonium hydroxide. The success of this solvent is based on the ability of copper and ammonia to complex with the glycol functionality of cellulose as shown inO Fig. 11. Because of the potential side reactions (oxidation and crosslinking, Norman compound formation), alternatives to both ammonia as well as copper have been developed. Cuen and cadoxen are related formulations based on the use of ethylene diamine and cadmium, respectively. The various combinations of alkali, ammonia. 

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