A process for purifying alkanesulfonic anhydride that includes feeding a stream containing alkanesulfonic anhydride, sulfuric acid, high boilers and residual low boilers into a melt crystallization to form crystals of the alkanesulfonic anhydride suspended in mother liquor, and solid-liquid separation to remove the crystals from the mother liquor.

A process for purifying alkanesulfonic anhydride that includes feeding a stream containing alkanesulfonic anhydride, sulfuric acid, high boilers and residual low boilers into a melt crystallization to form crystals of the alkanesulfonic anhydride suspended in mother liquor, and solid-liquid separation to remove the crystals from the mother liquor.

A process for purifying alkanesulfonic anhydride which includes:

(a) feeding a stream containing alkanesulfonic anhydride, sulfuric acid, high boilers and residual low boilers into a melt crystallization to form crystals of the alkanesulfonic anhydride suspended in mother liquor,

(b) performing a solid-liquid separation to remove the crystals from the mother liquor, and

(c) optionally washing the crystals to remove mother liquor adhering to the crystals.

A process for purifying alkanesulfonic anhydride which includes:

(a) feeding a stream containing alkanesulfonic anhydride, sulfuric acid, high boilers and residual low boilers into a melt crystallization to form crystals of the alkanesulfonic anhydride suspended in mother liquor,

(b) performing a solid-liquid separation to remove the crystals from the mother liquor, and

(c) optionally washing the crystals to remove mother liquor adhering to the crystals.

A compound of the formula (I)

ALKSO.sub.2OOSO.sub.2OX, wherein ALK is a branched or unbranched alkyl group, especially a methyl, ethyl, propyl, butyl, isopropyl, isobutyl group, or a higher alkyl group, and X=hydrogen, zinc, Aluminium, an alkali or alkaline earth metal.

A compound of the formula (I)

ALKSO.sub.2OOSO.sub.2OX, wherein ALK is a branched or unbranched alkyl group, especially a methyl, ethyl, propyl, butyl, isopropyl, isobutyl group, or a higher alkyl group, and X=hydrogen, zinc, Aluminium, an alkali or alkaline earth metal.

A compound of the formula:
CH.sub.3SO.sub.2OOSO.sub.2OH.

A compound of the formula:
CH.sub.3SO.sub.2OOSO.sub.2OH.

The present invention relates to a polymerizable composition comprising at least one ethylenically unsaturated, polymerizable compound and at least one oxime sulfonate compound of the formula I

QA.sub.aB.sub.bC.sub.c(I)

where a is 0, 1, 2, 3, 4 or 6, b is 0, 1, 2, 3, 4 or 6, and c is 0, 1, 2, 3, 4 or 6, where the sum of a+b+c is 1, 2, 3, 4 or 6
where
A is a group

##STR00001##

B is a group

##STR00002##

C is a group

##STR00003##

where # denotes the point of attachment to Q; X is S or NR.sup.14 and Q, R.sup.1, R.sup.2, R.sup.3 and R.sup.14 are as defined in claim 1 and in the description.

The present invention also relates to the use of the this composition, to novel oxime sulfonates and the use of the oxime sulfonates as thermal curing promoter.

The present invention relates to a polymerizable composition comprising at least one ethylenically unsaturated, polymerizable compound and at least one oxime sulfonate compound of the formula I

QA.sub.aB.sub.bC.sub.c(I)

where a is 0, 1, 2, 3, 4 or 6, b is 0, 1, 2, 3, 4 or 6, and c is 0, 1, 2, 3, 4 or 6, where the sum of a+b+c is 1, 2, 3, 4 or 6
where
A is a group

##STR00001##

B is a group

##STR00002##

C is a group

##STR00003##

where # denotes the point of attachment to Q; X is S or NR.sup.14 and Q, R.sup.1, R.sup.2, R.sup.3 and R.sup.14 are as defined in claim 1 and in the description.

The present invention also relates to the use of the this composition, to novel oxime sulfonates and the use of the oxime sulfonates as thermal curing promoter.