Patent GB-780205-A (GB)
Title: Synthetic glycols and their preparation
IPC: C09D5/23
Filed: 1954-12-08
Abstract: The invention comprises a mixture of glycols having the same number of carbon atoms and having the formula: <FORM:0780205/IV (a)/1> (wherein n and m are each 0 or 1; R, R1, R2, R3 and R4 are alkyl, aryl, aralkyl or alkaryl groups or hydrogen atoms, R3 and R4 also including substituted aryl or heterocyclic groups; and R5 is an alkenyl group), a mixture of C10 unsaturated glycols consisting substantially of 1,6 - dihydroxy - 2,5 - divinyl hexane, 1,8 - dihydroxy - 2 - vinyl - 5 - octene and 1,10 - dihydroxy - 3,7 - decadiene, a mixture of C10 saturated glycols containing as one of the major components 2 - ethyl - octane - 1,8 - diol, this latter compound per se, the mixtures of glycols obtained by the reaction of butadiene, sodium and, respectively, acetaldehyde, propionaldehyde and acetone by the method described below, and the mixtures of saturated glycols obtained by the hydrogenation of these mixtures. The invention also comprises the preparation of the unsaturated glycols by treating a conjugated diolefine with finely dispersed sodium or potassium in active aliphatic ether medium and preferably in presence of at least one dimerization activator, immediately reacting the resulting organometallic diene intermediate with a carbonyl compound and hydrolysing the metal derivatives of the glycols thus obtained. Diolefines which may be used include isoprene, dimethylbutadiene and methyl-1,3-pentadienes.  The alkali metal dispersion may be made in an inert hydrocarbon or ether preliminary to reaction with the diene, the medium for which reaction being any aliphatic monoether having a methoxy group, or mixtures thereof, or an acyclic or cyclic polyether derived by replacing all the hydroxyl hydrogen atoms of the polyhydric alcohol by alkyl groups. Dimerization activators comprise polycyclic aromatic hydrocarbons, e.g. naphthalene, phenanthrene, diphenyl, terphenyls, dinaphthyl and tetraphenyl ethylene, in concentrations of 0.1 to 10 weight per cent based on the amount of diolefines undergoing dimerization, and solid, friable attrition agents, e.g. alkali metal salts, sand, diatomaceous earth, "Cellite" (Registered Trade Mark), zircon, rutile and graphite. The dimerization is preferably conducted at below 0 DEG  C. and advantageously at -20 DEG  to -50 DEG  C., one molecular equivalent or a slight excess of alkali metal preferably being used. Carbonyl compounds which may be reacted with the mixture of dimetallodienes obtained in the dimerization step include butyraldehyde, isobutyraldehyde, 2-ethylhexaldehyde, furfural, salicylaldehyde, anisaldehyde, cinnamaldehyde, piperonal, vanillin, acrolein, crotonaldehyde, methyl ethyl ketone, diethyl ketone, acetophenone, benzophenone, methyl vinyl ketone, mesityl oxide, phorone and benzoquinone, or mixtures thereof, and, for the production of polymeric tertiary alcohols, organic esters.  This reaction is preferably conducted at below 50 DEG  C. and advantageously at -50 DEG  to 0 DEG  C., two equivalents of carbonyl compound being used for each molecule of dimetallic dimer.  The unsaturated glycol products can then be hydrogenated at the double bonds.  In examples: (1) a dispersion of sodium in iso-octane is contacted in presence of dimethyl ether and terphenyl with butadiene at -25 DEG  C., gaseous formaldehyde is admitted on completion of the initial reaction, the resulting disodio derivatives of the C10 glycols formed are treated with methanol and then water, solvents are removed from the organic layer and the residue is hydrogenated over platinum oxide giving a product which on fractionation yields 2,5-diethyl-1,6-hexanediol, 2 - ethyl - 1,8 - octanediol (bis - 3,5 - dinitrobenzoate described) and 1,10-decamethylene glycol; (2) acetaldehyde replaces the formaldehyde of Example (1) giving a final saturated product containing 2,11-dodecanediol, 3-ethyl-2,9-decanediol and 3,6-diethyl-2,7-octanediol; (3) propionaldehyde used similarly gives as final products a mixture of C14 saturated glycols; (4) acetone used similarly gives a different C14 glycol mixture.  Among other carbonyl compounds which may be used are alkyl substituted benzaldehydes, phenylacetaldehyde, dibenzylketone, benzyl phenyl ketone and alkyl or aralkyl substituted benzophenones.  Disodiooctadiene and benzaldehyde yield 1,10-diphenyldecanediol - 1,10; 1,8 - diphenyl - 2 - ethyloctanediol - 1,8 and 1,6 - diphenyl - 2,5 - diethyl hexanediol-1,6 and from phenylacetaldehyde the corresponding dibenzyl compounds are obtained.