Process for preparing electron deficient olefins
This invention relates to a process for preparing electron deficient olefins, such as 2-cyanoacrylates, using an acid catalyzed two-step process including an esterification reaction followed by a Knoevenagel condensation reaction.
1. A process for the preparation of a cyanoacrylate, steps of which comprise:
(a) reacting cyanoacetic acid and an alcohol in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield a cyanoacetate;
(b) reacting the so formed cyanoacetate from step (a) with a source of aldehyde, in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield a cyanoacrylate; and
(c) optionally, separating the so formed cyanoacrylate substantially free from the cyanoacetic acid, the alcohol and/or the catalyst and by-products.
2. A process for the preparation of an electron deficient olefin, steps of which comprise:
(a) providing as reactants:
(i) a 2-electron withdrawing group-substituted methylene compound embraced by:
wherein EWG represents an electron withdrawing group selected from the group consisting of cyano, halogens, nitro, isocyanate, sulfoxide and phosphine oxide; and R here represents hydrogen; and
(ii) an alcohol;
(b) reacting the 2-electron withdrawing group-substituted methylene compound and the alcohol in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield an electron deficient olefin precursor embraced by:
wherein EWG represents an electron withdrawing group selected from the group consisting of cyano, halogens, nitro, isocyanate, sulfoxide and phosphine oxide; and R here represents straight chain, branched, cyclic or fused C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, and C 6-20 aryl or C 7-20 alkaryl, with or without substitution or interruption by one or more heteroatoms;
(c) reacting the electron deficient olefin precursor and a source of aldehyde, in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield an electron deficient olefin; and
(d) optionally, separating the so formed electron deficient olefin substantially free from the reactants and by-products.
3. The process of claim 1 , wherein the catalyst comprising a lanthanide element or a transition element has one or more ligands bound to the element(s).
4. The process of claim 1 , wherein the catalyst comprises a lanthanide element.
5. The process of claim 1 , wherein the catalyst comprises a transition element.
6. The process of claim 1 , wherein the catalyst comprises ytterbium.
7. The process of claim 1 , wherein the catalyst comprises niobium.
8. The process of claim 3 , wherein the one or more ligands is selected from halogens, triflates, nitrates, mesylates or tosylates.
9. The process of claim 1 , wherein the alcohol is any mono-, di- or multi-functional hydroxyl compound.
10. The process of claim 1 , wherein the alcohol is any mono-, di- or multi-functional C 1-20 alkanol, C 2-20 alkenol, C 2-20 alkynol.
11. The process of claim 1 , wherein the alcohol is an aromatic alcohol.
12. The process of claim 1 , wherein the alcohol is phenol or benzyl alcohol.
13. The process of claim 2 , wherein the so-formed electron deficient olefin precursor is a cyanoacetate.
14. A process for the preparation of a cyanoacrylate, steps of which comprise:
(a) providing as reactants a cyanoacetic acid and an alcohol;
(b) reacting the cyanoacetic acid and the alcohol in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield a cyanoacetate;
(c) reacting the so formed cyanoacetate with a source of aldehyde, in the presence of a catalyst comprising a lanthanide element or a transition element, under appropriate conditions and for a time sufficient to yield a cyanoacrylate; and
(d) optionally, separating the so formed cyanoacrylate substantially free from the reactants and by-products.
15. The process of claim 2 , wherein the catalyst comprising a lanthanide element or a transition element has one or more ligands bound to the element(s).
16. The process of claim 2 , wherein the catalyst comprises a lanthanide element.
17. The process of claim 2 , wherein the catalyst comprises a transition element.
18. The process of claim 2 , wherein the catalyst comprises ytterbium.
19. The process of claim 2 , wherein the catalyst comprises niobium.
20. The process of claim 2 , wherein the alcohol is any mono-, di- or multi-functional hydroxyl compound.
21. The process of claim 2 , wherein the alcohol is any mono-, di- or multi-functional C 1-20 alkanol, C 2-20 alkenol, C 2-20 alkynol.
22. The process of claim 2 , wherein the alcohol is an aromatic alcohol.
23. The process of claim 2 , wherein the alcohol is phenol or benzyl alcohol.