Method for the production of α, ω-olefins by using the copper catalyzed coupling reaction of a Grignard reagent with an allylic substrate
View Patent ↗A process for the synthesis of linear α,ω-diolefins from an allylic substrate comprises the steps of a) forming the bis-Grignard reagent XMgCH 2 (CH 2 ) n CH 2 MgX from an α,ω-acyclic dihalide with X being a halogen; b) preparing a solution comprising an allylic substrate and a copper catalyst; c) catalyzing a coupling reaction by adding to the solution of step (b) the bis-Grignard reagent of step (a); and d) isolating and purifying the α,ω-olefin coupling reaction product.
1. A process for the synthesis of linear α,ω-diolefins from an allylic substrate comprising the steps of:
(a) forming a bis-Grignard reagent XMgCH 2 (CH 2 ) n CH 2 MgX wherein n=1 to 18 from an α,ω-acyclic dihalide with X being a halogen;
(b) preparing a solution comprising an allylic substrate and a copper catalyst;
(c) catalyzing a coupling reaction by adding to the solution of step (b) said bis-Grignard reagent of step (a); and
(d) isolating and purifying the α,ω-olefin coupling reaction product.
2. The process of claim 1 wherein said α,ω-diolefin is an α,ω-symmetrical diene.
3. The process of claim 2 wherein said symmetrical diene contains from 5 to about 30 carbon atoms.
4. The process of claim 3 wherein said symmetrical diene is substituted other than at the terminal double bonds by alkyl, aryl, and cycloalkyl groups.
5. The process of according to claim 1 wherein said a, w acyclic dihalide contains a hydrocarbon chain length of from 3 to 10 carbons and the dihalide is a chloride or bromide.
6. The process of claim 1 wherein the said bis-Grignard reagent formation is carried out in an inert solvent system selected from the group consisting of diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, dioxane, tetrahydrofuran, cyclohexane, toluene, and mixtures thereof.
7. The process of claim 6 wherein the said solvent system comprises tetrahydrofuran.
8. The process of claim 1 wherein said allylic substrate is selected from the group consisting of allyl bromide, allyl chloride, allyl acetate, allyl propionate, isopropanoate, butyrate, iso-butyrate, sec-butyrate, t-butyl esters, allyl tosylate, and mixtures thereof.
9. The process of claim 1 wherein said catalyst is a lithium tetrachlorocuprate catalyst.
10. The process of claim 1 wherein said catalyst is a lithium trichlorocuprate.
11. The process of claim 1 , wherein the concentration of said catalyst is 0.1-10 mol % based on the amount of dihalide used to form the bis-Grignard reagent.
12. The process of claim 1 , wherein the reaction temperature is from about −40° C. to about 0° C.
13. The process of claim 1 , wherein said coupling is carried out by combining the pre-formed catalyst with either the allylic substrate or the Grignard reagent, and then adding the Grignard reagent to the allylic substrate.
14. The process of claim 1 wherein said α,ω-diolefin is selected from the group consisting of 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, 1,14-pentadecadiene, 1,15-hexadecadiene, 1,16-heptadecadiene, 1,17-octa-decadiene, 1,18-nonadecadiene, and 1,19-eicosadiene.