Hexamethylene glycol 1 6-Hexanediol

This preparation illustrates the use of the copper-chromium oxide catalyst in the r uotion of esters of dibasic acids to glycols  

This preparation illustrates the Reforrnatsky reaction, which consists in the interaction of a carbonyl compound, an a-halogen ester (e.g., ethyl bromo-acetate) and zinc In the presence of ether or benzene, followed by hydrolysis. 

It may be pointed out that dehydration of phydroxy esters with fused potassium hydrogen sulphate, acetic anhydride, phosphoric oxide or with tkionyl chloride in benzeue solution leads to ap-unsaturated esters containing some Py-unsaturated ester the proportion of the latter depends not only upon the structure of the ester but also upon the dehydrating agent used. Dehydration occasionally occurs during the reaction itself or upon attempted distillation. 

It is probable that the reaction proceeds through an organic zinc derivative, analogous to a Grignard reagent, formed by interaction of the a-halogen ester 

Place 65 g. of clean dry zinc wool and a few crystals of iodine in a 2 5 litre three-necked flask, equipped with an efficient reflux condenser with drying tube, a mechanical stirrer, and a dropping funnel. Prepare a mixture 

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Note. Both tetramethylene glycol (1 4-butanediol) and hexamethylene glycol (1 6-hexanediol) may be prepared more conveniently by copper-chromium oxide reduction (Section VI,6) or, for small quantities, by reduction with lithium aluminium hydride (see Section VI, 10). 

Hexamethylene glycol Hexamethylenediol 1,6-Hexanediol a,eo-Hexanediol HSDB 6488 NSC 508. Crystals mp = 42.8° bp = 208° insoluble in CsHe, slightly soluble in Et20, soluble In H2O, EtOH, Me2CO. 

Hexanedioi Hexane-1,6-dioi oc-a>-Hexanediol. See Hexamethylene glycol... 

Hexamethylene diisocyanate trimer. See Hexamethylene diisocyanate polymer Hexamethylenediol. See Hexamethylene glycol Hexamethylene distearate. See Hexanediol distearate... 

Hexamethylene glycol CAS 629-11-8 EINECS/ELINCS 211-074-0 Synonyms 1,6-Dihydroxyhexane HDO Hexamethylenediol 1,6-Hexanediol Hexane-1,6-diol... 

Hexamethylene glycol dimethacrylate. See 1,6-Hexanediol methacrylate Hexamethylene m i ne CAS 111-49-9 EINECS/ELINCS 203-875-9 UN 2493... 

Synonyms Hexamethylene glycol dimethacrylate 1,6-Hexanediol dimethacrylate ... 

Poly( 1,6-hexanediol/neopentyl Adipic acid-hexamethylene glycol 25214-14-6 Hexane oic acid, polder with R (C5H 14O2... 

Trimethylene dibromide (Section 111,35) is easily prepared from commercial trimethj lene glycol, whilst hexamethylene dibromide (1 O dibromohexane) is obtained by the red P - Br reaction upon the glycol 1 6-hexanediol is prepared by the reduction of diethyl adipate (sodium and alcohol lithium aluminium hydride or copper-chromium oxide and hydrogen under pressure). Penta-methylene dibromide (1 5-dibromopentane) is readily produced by the red P-Brj method from the commercially available 1 5 pentanediol or tetra-hydropyran (Section 111,37). Pentamethylene dibromide is also formed by the action of phosphorus pentabromide upon benzoyl piperidine (I) (from benzoyl chloride and piperidine) ... 

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