Prepn. of calcium formate from calcium hydroxide and formaldehyde - uses calcium hydroxide with short solubility time, in presence of inhibitor for auto-condensation of formaldehyde

摘要

In prepn. of Ca formate by reaction of Ca(OH)2 with HCHO in molar ratio of 1:4, in an aq. phase at 40-90 deg. C, in presence of a catalytic amt. of an inhibitor for the auto condensation of the HCHO, Ca(OH)2 with a solubility time of less than 200 secs. for 99% dissolution, determined by conductivity measurement at 20 deg. C after addn. of Ca(OH)2 as a 20 wt.% aq. suspension (milk of lime) to deionised water free from CO2 at a concn. of 0.8 g/l of Ca (OH)2 is used. After the reaction, the inhibitor is sepd. by pptn. and filtration or by ion-exchange, and at the same time, or later, HCHO still present is converted to formoses at pH above 7 by autocondensation, and Ca formate is recovered from the aq. soln. by crystallisation. USE/ADVANTAGE - Ca(OH)2 is quantitatively converted, the space/time yield is increased, and yields are high. The Ca formate is free from HCHO and inhibitors. Ca formate is used in tanning, to produce formic acid, as setting accelerator in cement, as silation aid, and as fodder additive in animal feeding