METHYLIDENE MALONATE PROCESS
An improved process for the production of methylidene malonates is attained by use of select iminium salt reactants.
1 . A method of producing methylidene malonates said method comprising reacting a malonic acid ester with an iminium salt of the formula
wherein R 4 and R 5 are each independently H or a hydrocarbon and R 6 and R 7 are each a hydrocarbon or substituted hydrocarbon or together form a bridge whereby the nitrogen atom, R 6 and R 7 together form a ring structure; provided that neither of R 6 and R 7 is a hydrocarbon moiety comprising a tertiary carbon attached to the N atom and X is an anion.
2 . The method of claim 1 wherein R 4 and R 5 are each H and R 6 and R 7 are each independently alkyl, or alkenyl.
3 . The method of claim 1 wherein X is a halogen, a non-nucleophilic anion, and/or acidic anion.
4 . The method of claim 1 wherein X is a halogen, a carboxylate or a sulfonate.
5 . The method of claim 1 wherein X is selected from chloride, bromide, iodide, AsF 6 , SbF 6 , PF 6 , BF 4 , CH 3 SO 3 , CF 3 SO 3 , benzenesulfonate, para-toluenesulfonate, acetate, propionate, isobutyrate, pivalate, sufate, bisulfate, perchlorate, SbCl 6 , SbCl 3 , and SnCl 5 .
6 . The method of claim 1 wherein the malonic acid ester has the formula
wherein, in the case of a mono-ester, one of R 1 and R 2 is H and the other a C 1 to C 18 hydrocarbon or heterohydrocarbon group, the latter having one or more nitrogen, halogen, or oxygen atoms or, in the case of a diester, both R 1 and R 2 , which may be the same or different, are each independently selected from C 1 to C 18 hydrocarbon or heterohydrocarbon groups, the latter having one or more nitrogen, halogen, or oxygen atoms.
7 . The method of claim 6 wherein R 1 and R 2 are both hydrocarbon and/or heterohydrocarbon groups and represent a C 1 to C 10 linear or branched alkyl group, a C 3 to C 6 alicyclic group, a C 2 to C 6 alkenyl group, or a C 2 to C 6 alkynyl group, either or both of which may be substituted with or contain an ether, epoxide, halo, ester, cyano, aldehyde, keto or aryl group.
8 . The method of claim 6 wherein both R 1 and R 2 are hydrocarbon or heterohydrocarbon groups wherein at least one contains an ester linkage.
9 . The method of claim 6 wherein at least one of the R 1 and R 2 groups is of the formula:
—(CH 2 ) n —COOR 3
wherein R 3 is a C 1 to C 17 hydrocarbon or heterohydrocarbon group, the latter having one or more nitrogen, halogen, or oxygen atoms, and n is an integer of from 1 to 5.
10 . The method of claim 6 wherein the malonic acid ester is a diester and a least one of R 1 and R 2 is a group is of the formula:
—(CH 2 ) 2 —COOR 3
wherein R 3 is independently a C 1 to C 17 hydrocarbon or heterohydrocarbon group, the latter having one or more nitrogen, halogen, or oxygen atoms, and n is an integer of from 1 to 5.
11 . The method of claim 10 wherein R 3 is independently a C 1 to C 6 lower alkyl and n is 1 or 2.
12 . The method of claim 1 wherein the equivalent weight of iminium salt to malonic acid ester is from 1:1 to 10:1.
13 . The method of claim 1 wherein the equivalent weight of iminium salt to malonic acid ester is from 1:1 to 6:1.
14 . The method of claim 1 wherein the equivalent weight of iminium salt to malonic acid ester is from 1:1 to 4:1.
15 . The method of claim 1 wherein the iminium salt is formed in-situ and the malonic acid ester is directly added to the iminium reaction product.
16 . The method of claim 15 wherein the in-situ reaction involves an excess molar equivalent of the anhydride or acid chloride activation agent.
17 . The method of claim 15 wherein the iminium salt is formed by the reaction of an acid halide or an acid anhydride with a 1,1-diaminoalkane.
18 . The method of claim 1 wherein the reaction is performed in the presence of a polar solvent.
19 . The method of claim 1 wherein the reaction is performed in the presence of a non-polar solvent and the anion of the iminium salt is a carboxylate.
20 . A method of producing methylidene malonates comprising the steps of
(a) forming an iminium salt corresponding to the formula
wherein R 4 and R 5 are each independently H or a hydrocarbon and R 6 and R 7 are each a hydrocarbon or substituted hydrocarbon or together form a bridge whereby the nitrogen atom, R 6 and R 7 together form a ring structure; provided that neither of R 6 and R 7 is a hydrocarbon moiety comprising a tertiary carbon attached to the N atom and X is an anion, and
(b) allowing the so formed iminium salt to react with a malonic acid ester.
21 . The method of claim 20 wherein the iminium salt is formed by the reaction of an acid halide or an acid anhydride with a 1,1-diaminoalkane.