GB787128A - Process for the production of esters and/or polyesters from a tricyclodecane derivative - Google Patents

Abstract

Esters and/or polyesters are obtained by converting 8-hydroxytricyclodec-4-ene into 8-hydroxytricyclodecane-4-al by the addition of carbon monoxide and hydrogen in the presence of a cobalt catalyst, converting the 8-hydroxytricyclodecane - 4 - al into 8 - hydroxytricyclodecane-4-carboxylic acid either directly by oxidation with an oxygen-containing gas, or indirectly by hydrogenating the 8-hydroxytricyclodecane - 4 - al to 8 - hydroxytricyclodecane - 4 - methylol, subjecting the methylol in a hydrocarbon diluent to treatment with a molten alkali metal hydroxide to yield an alkali metal salt of 8-hydroxy-tricyclodecane-4-carboxylic acid and converting the salt into the free acid, and esterifying the 8-hydroxytricyclodecane-4-carboxylic acid with itself by heating the acid. The 8-hydroxytricyclodec-4-ene is preferably first diluted with a low boiling hydrocarbon, e.g. an aromatic hydrocarbon such as benzene, toluene or xylene and the addition of carbon monoxide and hydrogen is effected in known manner with the use of a cobalt-containing catalyst at elevated temperature and pressure. When the catalyst is an aqueous cobalt sulphate-magnesium sulphate solution having a pH below 7 such as is employed in the process described in Specification 711,696, the aqueous catalyst solution is separated from the raw aldehyde which will still contain some cobalt and the raw aldehyde is then reacted with water gas at 180-200 DEG C. and at 200-300 atmospheres pressure until no further absorption of gas occurs. The methylol compound formed is then separated from the residual catalyst by filtration and any diluent present is removed by distillation. It is also possible to treat the 8-hydroxy-tricyclodecane-4-al, after the separation of the catalyst solution, with water, as described in Specification 734,030 for the production of oxo aldehydes. This permits residues of catalyst metal to be readily separated from the 4-al and effects cleavage of any acetals present. The 4-al may then be converted into the 4-methylol compound by treating with hydrogen in the presence of water and a reduced cobalt catalyst, e.g. a cobalt-magnesia-thorium-kieselguhr catalyst. This hydrogenation step may be carried out in the presence of a lower aliphatic alcohol, e.g. by using aqueous ethanol. The conversion of the 4-al into the 4-carboxylic acid by oxidation with air may be effected at a pH below 7 or with the addition of an alkali such as soda or potash, but the yields obtained by this method are generally low. It is preferred to prepare the 4-carboxylic acid by treating the 4-methylol with a molten alkali metal hydroxide in the presence of a hydrocarbon diluent, e.g. dodecane, at a temperature not appreciably exceeding 250 DEG C. and preferably in the presence of an inert gas, e.g. nitrogen or hydrogen. The hydrogen formed is removed and water is added to give an aqueous solution containing the salt of the 4-carboxylic acid. This solution may be decolorized, preferably after neutralization of excess alkali, by treating with hydrogen in the presence of a nickel catalyst, e.g. a nickel-magnesia-kieselguhr catalyst at 210 DEG C. and with a hydrogen pressure of 150-250 atmospheres, the catalyst being then separated and the solution extracted with a solvent, e.g. a low boiling ester or 8-ketotricyclodecane-4 to remove unsaponified constituents. The extracted salt solution is then acidified with a mineral acid, e.g. hydrochloric acid, to a pH value of 1 to 2 to form the free-4-carboxylic acid. The water present is decanted and the hydroxy acid is finally dehydrated by dissolving in ether and evaporating off the ether. When the free 4-carboxylic acid is heated to temperatures in excess of 60 DEG C., esterification occurs with the elimination of water and this esterification will proceed to the formation of a polyester. If the hydroxycarboxylic acid is heated for several hours in an inert atmosphere, e.g. nitrogen, at normal pressure, to a temperature above 60 DEG C. and not higher than about 300 DEG C. and is then heated for a further period, e.g. for 1 hour, at about 300 DEG C. at a pressure of about 0.5 mm. of mercury an almost colourless resin having an average molecular weight of about 3000 is obtained. An example for the production of such a resin is given, the 4-carboxylic acid product being obtained from the 4-al compound by converting the latter to the 4-methylol compound which is then reacted with a mixture of sodium and potassium hydroxides in dodecane to form the acid salt from which the free acid is liberated. Specifications 775,298 and 779,052 also are referred to.ALSO:Polyesters of 8-hydroxytricyclodecane-4-carboxylic acid are obtained by heating the acid to effect self-esterification. The -4-carboxylic acid is obtained by converting 8-hydroxytricyclodec-4-ene into 8-hydroxytricyclodecane-4-al by the addition of carbon monoxide and hydrogen in the presence of a cobalt catalyst and converting the -4-al compound to the -4-carboxylic acid either directly by oxidation with an oxygen-containing gas or indirectly by first hydrogenating the -4-al to the corresponding -4-methylol compound and then treating the latter in a hydrocarbon diluent with a molten alkali metal hydroxide to yield an alkali metal salt of the -4-carboxylic acid from which the free acid is liberated (see Group IV (b)). When the free acid is heated to temperatures above 60 DEG C. esterification occurs with the elimination of water to form a polyester. If the acid is heated for several hours in an inert atmosphere, e.g. nitrogen, at normal pressure, to a temperature above 60 DEG C. and not higher than about 300 DEG C. and is then heated for a further period e.g. for 1 hour, at about 300 DEG C. at a pressure of about 0.5 mm. of mercury an almost colourless resin having an average molecular weight of about 3000 is obtained and an example for the production of a polyester by this method is given.