Process for the preparation of low molecular weight polyhydroxyl compounds
AssigneeBayer Aktiengesellschaft
InventorsEdgar Mohring, Kuno Wagner, Hanns P. Muller
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Abstract
The instant invention relates to an improved process for the preparation of low molecular weight polyalcohols by the catalytic hydrogenation of a mixture of different low molecular weight hydroxy aldehydes, hydroxy ketones and optionally also polyhydric alcohols such as is formed from the autocondensation of formaldehyde (such a mixture will hereinafter be referred to as "formose"). The invention also relates to the use of these polyalcohols for the production of polyurethane resins.
Claims3
In a process for the production of a polyether comprising alkoxylating an active hydrogen-containing material, the improvement wherein the active hydrogen containing material is produced by the reduction of formose at a temperature of from 80.degree. to 220.degree. C. and a hydrogen pressure of from 50 to 300 bar in the presence of a metal catalyst characterized in that
- (1) a solution at a concentration of at least 20% of the product which is required to be reduced is introduced batch-wise into a reactor so that the proportion of reducible groups, determined as carbonyl groups, in the product mixture inside the reactor does not exceed 2% by weight,
- (2) the pH of the hydrogenation reaction is adjusted to between 7.5 and 12.5,
- (3) the total quantity of catalyst used, based on the total quantity of starting material which is to be reduced, is from 10.sup.-4 to 5.times.10.sup.-2 % by weight, the catalyst content remaining constant in the reactor, and
- (4) the reaction product is withdrawn batch-wise from the reactor after the proportion of reducible groups (determined as carbonyl groups) has fallen below 0.15% by weight.
In a process for the production of a polyester polyol by reacting a carboxylic acid with a polyhydroxyl material, the improvement wherein the polyhydroxyl material is produced by the reduction of formose at a temperature of from 80.degree. to 220.degree. C. and a hydrogen pressure of from 50 to 300 bar in the presence of a metal catalyst, characterized in that
- (1) a solution at a concentration of at least 20% of the product which is required to be reduced is introduced batch-wise into a reactor so that the proportion of reducible groups, determined as carbonyl groups, in the product mixture inside the reactor does not exceed 2% by weight,
- (2) the pH of the hydrogenation reaction is adjusted to between 7.5 and 12.5,
- (3) the total quantity of catalyst used, based on the total quantity of starting material which is to be reduced, is from 10.sup.-4 to 5.times.10.sup.-2 % by weight, the catalyst content remaining constant in the reactor, and
- (4) the reaction product is withdrawn batch-wise from the reactor after the proportion of reducible groups (determined as carbonyl groups) has fallen below 0.15% by weight.
Process for the preparation of cellular or non-cellular polyurethane resins by the reaction of
- (a) polyisocyanates with
- (b) compounds containing at least 2 active hydrogen atoms and having a molecular weight of from 32 to 400, optionally
- (c) compounds containing at least 2 active hydrogen atoms and having a molecular weight of from 400 to 10,000, and optionally
- (d) blowing agents, catalysts and other known additives, characterized in that the compounds used as component (b) comprise polyhydric alcohols prepared by the reduction of formose at a temperature of from 80.degree. to 220.degree. C. and a hydrogen pressure of from 50 to 300 bar in the presence of a metal catalyst, characterized in that
- (1) a solution at a concentration of at least 20% of the product which is required to be reduced is introduced batch-wise into a reactor so that the proportion of reducible groups, determined as carbonyl groups, in the product mixture inside the reactor does not exceed 2% by weight
- (2) the pH of the hydrogenation reaction is adjusted to between 7.5 and 12.5,
- (3) the total quantity of catalyst used, based on the total quantity of starting material which is to be reduced, is from 10.sup.-4 to 5.times.10.sup.-2 % by weight, the catalyst content remaining constant in the reactor, and
- (4) the reaction product is withdrawn batch-wise from the reactor after the proportion of reducible groups (determined as carbonyl groups) has fallen below 0.15% by weight.
Dependencies are inferred from the claim text.