A process for isolating polymethylolalkanoic acids or monomethylolalkanoic acids of the formula (I)
1
where R are identical or different and are each a substituted or unsubstituted hydrocarbon radical or a methylol group, which have been prepared from the corresponding polymethylolalkanals or monomethylolalkanals of the formula (II)
2
where R are as defined above, by oxidation using an aqueous solution of hydrogen peroxide comprises
a) carrying out a crystallization followed by a liquid/solid separation (B) to give the acid as first crystallized material (
2
a
) plus mother liquor (
3
),
b) producing further crystallized material (
2
b
) in the mother liquor (
3
) and separating the resulting mother liquor (
3
) from the further crystallized material (
2
b
) in a further solid/liquid separation (C), and
c) disposing of the resulting mother liquor (
3
) which has been depleted in the acid.
一种用于分离公式(I)1中R相同或不同且分别为取代或未取代的碳氢基团或甲基醇基制备的相应的公式(II)2中的聚
甲醇基烷醛或单
甲醇基烷醛的聚
甲醇基烷酸或单
甲醇基烷酸的方法,其中R如上所定义,通过使用
过氧化氢的
水溶液氧化包括:a)进行结晶,然后进行液固分离(B),以得到作为第一次结晶物质(2a)的酸和母液(3),b)在母液(3)中产生进一步的结晶物质(2b),并在进一步的固液分离(C)中将所得到的母液(3)与进一步的结晶物质(2b)分离,并c)处置已耗尽酸的所得到的母液(3)。