Process for the preparation of low molecular weight polyhydroxyl compounds

Claim 2

A process for the preparation of mixtures of low molecular weight polyhydric alcohols and hydroxyaldehydes and-hydroxyketones by the condensation of formaldehyde by itself in the presence of from 0.01-10% by weight, based on the quantity of formaldehyde, of metal compounds as catalyst and from 0.1-10% by weight, based on the formaldehyde, of co-catalysts based on compounds which are capable of enediol formation, the improvement which comprises condensing aqueous formalin solutions and/or paraformaldehyde dispersions con-taining from 20-65% by weight of formaldehyde at a reaction temperature of from 70-120°C in the presence of (I) a soluble or insoluble compound of a metal of the 2nd -4th main or 1st to 8th sub-group of the Periodic System of Elements, optionally bound to a high molecular weight carrier, and (II) a co-catalyst prepared by partial oxidation of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols, the pH of the reaction solution being maintained at between 6.0 and 9.0 by controlled addition of an inorganic and/or organic base up to a conversion rate of from 5 to 40% and thereafter at between 4.5 and 8.0 until termination of the condensation reaction to that during this second phase the pH is lower by 1.0 - 2.0 units than in the first phase of the reaction; and then stopping the reaction by inactiva-tion of the catalyst in known manner when the residual formaldehyde content is 0 - 10% by weight; removing catalyst; and, optionally reducing the aldehyde and keto groups present in the reaction product to hydroxyl groups.

Claim 3

The process of Claim 1, wherein the catalysts used are ion-exchangers charged with metal ions.

Claim 4

The process of Claim 1, wherein the partial oxidation is conducted using an aqueous solution of an oxidizing agent from the group consisting of hydrogen peroxide, nitric acid, sodium hypochlorite, ammonium peroxy-disulfate, salts of heptavalent manganese or lead(IV) salts.

Claim 5

The process of Claim 1, wherein the divalent or higher valent alcohols having at least two hydroxyl groups adjacent to each other or mixtures of such alcohols are used in quantities of from 0.001 OH equivalents to 0.1 OH equivalents, based on 1 mol of formaldehyde, to prepare the co-catalyst.

Claim 6

The process of Claim 1, wherein the partial oxidation is conducted using an oxidizing agent in a quantity of at least 0.001 equivalents per mol of formaldehyde and not more than a quantity equivalent to the quantity of alcohol used in the process.

Claim 7

The process of Claim 1, wherein a lead(IV) compound is used both as the catalyst and as an oxidizing agent for the partial oxidation.

Claim 8

The process of Claim 1, wherein the hydroxy-aldehydes and hydroxyketones contained in the reaction products are subsequently reduced with formaldehyde by a crossed Cannizzaro reaction at a pH range of 9 - 13.

Claim 9

The process of Claim 1, wherein formaldehyde condensation is carried out continuously in a cascade of stirrer vessels.

Claim 10

The process of Claim 1, wherein the condensation of formaldehyde is carried out continuously in a reaction tube.

Claim 11

A process for the preparation of polyurethane resins comprising reacting a) polyisocyanates with b) low molecular weight polyhydric alcohols and hydroxyaldehydes and hydroxyketones produced by the condensation of formaldehyde by itself in the presence of from 0.01-10% by weight, based on the quantity of form-aldehyde, of metal compounds as catalyst and from 0.1-10% by weight, based on the formaldehyde, of co-catalysts based on compounds which are capable of enediol formation, the com-ponent b) being produced by condensing aqueous formalin solutions and/or paraformaldehyde dispersions containing from 20-65% by weight of formaldehyde at a reaction temperature of from 70-120°C in the presence of (I) a soluble or insoluble compound of a metal of the 2nd - 4th main or 1st to 8th sub-group of the Periodic System of Elements, optionally bound to a high molecular weight carrier, and (II) a co-catalyst prepared by partial oxidation of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols, the pH of the reaction solution being maintained at between 6.0 and 9.0 by controlled addition of an inorganic and/or organic base up to a conversion rate of from 5 - 40% and thereafter at between 4.5 and 8.0 until termination of the condensation reaction so that during this second phase the pH is lower by 1.0 - 2.0 units than in the first phase of the reaction; and then stopping the reaction by inactivation of the catalyst in known manner when the residual formaldehyde content is 0-10% by weight; removing catalyst; and, optionally reducing the aldehyde and keto groups present in the reaction product to hydroxyl groups; c) higher molecular weight polyhydroxyl compounds and/or other chain lengthening agents, optionally in the presence of d) blowing agents, catalysts and other known additives.

Claim 12

A process for the preparation of polyurethane resins comprising reacting a) polyisocyanates with b) low molecular weight polyhydric alcohols and hydroxyaldehydes and hydroxyketones produced by the condensation of formaldehyde by itself in the presence of from 0.01-10% by weight, based on the quantity of form-aldehyde, of metal compounds as catalyst and from 0.1-10% by weight, based on the formaldehyde, of co-catalysts based on compounds which are capable of enediol formation, the com-ponent b) being produced by condensing aqueous formalin solutions and/or paraformaldehyde dispersions containing from 20-65% by weight of formaldehyde at a reaction temperature of from 70-120°C in the presence of (I) a soluble or insoluble compound of a metal of the 2nd - 4th main or 1st to 8th sub-group of the Periodic System of Elements, optionally bound to a high molecular weight carrier, and (II) a co-catalyst prepared by partial oxidation of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols, the pH of the reaction solution being maintained at between 6.0 and 9.0 by controlled addition of an inorganic and/or organic base up to a conversion rate of from 5 - 40% and thereafter at between 4.5 and 8.0 until termination of the condensation reaction so that during this second phase the pH is lower by 1.0 - 2.0 units than in the first phase of the reaction; and then stopping the reaction by inactivation of the catalyst in known manner when the residual formaldehyde content is 0-10% by weight; removing catalyst; and, optionally reducing the aldehyde and keto groups present in the reaction product to hydroxyl groups; c) higher molecular weight polyhydroxyl compounds and/or other chain lengthening agents, optionally in the presence of d) blowing agents, catalysts and other known additives.