DE941667C - Process for the preparation of 1,5-glycols containing ether groups - Google Patents

Description

Process for the preparation of 1 5 glycols containing ether groups Es it is known that diols are obtained when an a-substituted acrolein is mixed with aqueous dilute alkali and a lower aliphatic alcohol with a straight carbon chain treated at moderate temperatures and catalytically hydrogenated the reaction mixture. In this way, small amounts of 2-methoxymethyl-2, 4-dimethylpentane-1,5-diol obtained (cf. German patent 894 109).

It has now been found that such ether groups can be found I, 5-glycols obtained in considerably better yields; when looking at solutions of a-alkylacroleins in an excess of alcohols without the addition of water at about - 50 to at most + 30 ° allows small amounts of alkali metal to act, neutralizing the reaction mixture and then catalytically hydrogenated.

When alcohols ROH are reacted with a-alkylacroleins Cm2 = c (R ') - GHO in the presence of small amounts of alkali metal alcoholate, substituted glutaraldehydes are formed, presumably with the addition of two molecules of the aldehyde and the addition of one molecule of alcohol to the ends of the resulting structure: In the catalytic hydrogenation of the neutralized reaction mixture, the aldehyde groups are reduced to oxy groups, so that ether group-containing I, s-glycols of the general formula receives.

Suitable a-alkylacroleins are, for. B. the a-methyl-, the a-ethyl- or. the a-hexyla; crolein. As alcohols you can, for. B. methanol, ethanol, propanol, Use octanol or benzyl alcohol.

Zur'katalytischen hydrogenation of the neutralized reaction mixture the usual catalysts are used, e.g. B. nickel, cobalt or copper, appropriate in the form of Raney catalysts, or noble metals on supports. The cheapest in each case Hydrogenation times, temperatures, and hydrogen pressures vary depending on the catalyst different and can easily be determined by preliminary tests. When using Raney nickel works z. B. at 1200 and 200 atm. Hydrogen pressure.

Not after filtering off the catalyst and distilling off converted starting materials in good yield residual ether groups 1,5-glycols are oils of a glycerine-like character.

Those that differ from starting materials with lower alkyl groups derive are miscible with water in any ratio. They are valuable intermediate products, z. B. for plastics, plasticizers and textile auxiliaries.

The parts mentioned in the examples are parts by weight.

Example I To a solution of 0.8 parts of sodium in 560 parts of methanol 350 parts of α-methylacrolein are allowed to flow in over the course of 2 hours at o "with stirring, if necessary, by occasionally adding small amounts of sodium methylate the pH of the reaction mixture. stops at about 8. Neutralized after a further 3 hours about 2.9 parts of concentrated sulfuric acid are added, 20 parts of Raney nickel added and hydrogenated at 120 "with hydrogen at 200 atm. pressure until no hydrogen more is recorded. It is filtered, the excess methanol and distilled other volatile products and receives an oil as residue, the bulk of which boils under 2 mm pressure at 124 to I26 ". It consists of 2,4-dimethyl-2-methoxymethyl-pentamethylene glycol- (I, 5). The yield is 300 parts. The glycol is with water in every proportion miscible.

Example .2 Use in place of the amount used in Example I. Methanol 800 parts of ethanol. If the procedure is otherwise the same, 3Io is obtained Parts 2, 4-dimethyl - 2 ethoxymethylpentamethylene glycol- (1, 5) with a boiling point of 129/1320 under 2 mm pressure, which has properties similar to those described in Example I. Glycol.

Claims (1)

PATENT APPEAL: Process for the production of ether groups containing I, 5-glycols, characterized in that solutions of α-alkylacroleins in an excess of alcohols without the addition of water at about - 5 "to at most + 30 ° small amounts of alkali metal can act ', the reaction mixture is neutralized andJ then catalytically hydrogenated.