Process for producing exo-tetrahydrodicyclopentadiene
A process for isomerizing endo-hydrogenated dicyclopentadiene to form the corresponding exo-isomer using a stable, pumpable liquid aluminum halide catalyst which includes steps of providing a first solution containing a hydrogenated dicyclopentadiene compound that is dissolved in a hydrocarbon solvent, adding a cosolvent to the first solution to form a second solution, adding an aluminum halide to the second solution, and isomerizing the hydrogenated dicyclopentadiene compound in the presence of dissolved aluminum halide which acts as a catalyst to produce the corresponding exo-isomer.
1. A process for isomerization of an endo-hydrogenated dicyclopentadiene compound to produce a corresponding exo-hydrogenated dicyclopentadiene compound, comprising:
providing a first solution containing an endo-hydrogenated dicyclopentadiene compound dissolved in a hydrocarbon solvent;
adding a cosolvent to the first solution to form a second solution;
adding an aluminum halide catalyst to the second solution; and
isomerizing dissolved endo-hydrogenated dicyclopentadiene compound in the presence of dissolved aluminum halide catalyst to produce exo-hydrogenated dicyclopentadiene compounds, wherein the cosolvent is a linear alkyl ester of a carboxylic acid.
2. The process of claim 1 , wherein the endo-hydrogenated dicyclopentadiene compound is endo-tetrahydrodicyclopentadiene.
3. The process of claim 1 , wherein the endo-hydrogenated dicyclopentadiene compound is endo-tetrahydromonomethyl dicyclopentadiene or endo-tetrahydrodimethyl dicyclopentadiene.
4. The process of claim 1 , wherein the alkyl ester of a carboxylic acid has from five to nine carbon atoms.
5. The process of claim 1 , wherein the alkyl ester of a carboxylic acid is a methyl ester of a carboxylic acid.
6. The process of claim 5 , wherein the alkyl ester of a carboxylic acid has from five to nine carbon atoms.
7. The process of claim 1 , wherein the alkyl ester of a carboxylic acid is methyl butanoate.
8. The process of claim 1 , wherein the alkyl ester of a carboxylic acid is selected from propyl propanoate and ethyl butanoate.
9. The process of claim 1 , wherein the hydrocarbon solvent is comprised of at least 50 percent linear paraffins by weight.
10. The process of claim 1 , wherein the aluminum halide is aluminum chloride.
11. The process of claim 10 , wherein a molar ratio of aluminum chloride to the alkyl ester of a carboxylic acid is greater than 1.4:1.
12. The process of claim 10 , wherein a molar ratio of aluminum chloride to the alkyl ester of a carboxylic acid is greater than 1.6:1.
13. The process of claim 10 , wherein a molar ratio of aluminum chloride to the alkyl ester of a carboxylic acid is greater than 1.7:1.
14. The process of claim 10 , wherein a molar ratio of aluminum chloride to the alkyl ester of a carboxylic acid is up to 1.8:1.
15. The process of claim 1 , wherein the first solution comprises a mixture of endo-hydrogenated dicyclopentadiene having a Bromine Index of 10 or less.
16. The process of claim 1 , wherein the exo-hydrogenated dicyclopentadiene compounds partition into an upper liquid phase from the lower liquid phase containing the aluminum halide catalyst, and which further comprises decanting the upper liquid phase from the lower liquid phase, adding fresh endo-hydrogenated dicyclopentadiene to the lower liquid phase, optionally adding additional aluminum halide, and isomerizing the fresh endo-hydrogenated dicyclopentadiene.
17. The process of claim 16 , wherein the steps of claim 16 are repeated one or more times.
18. A process for isomerization of an endo-hydrogenated dicyclopentadiene compound to produce a corresponding exo-hydrogenated dicyclopentadiene compound, comprising:
(a) providing a liquid system comprising a hydrocarbon solvent, a cosolvent that enhances dissolution of an aluminum halide, and endo-hydrogenated dicyclopentadiene compound to form a solution;
(b) adding an aluminum halide catalyst to the solution;
(c) isomerizing the endo-hydrogenated dicyclopentadiene compound;
(d) allowing product exo-hydrogenated dicyclopentadiene compounds to separate into an upper liquid phase;
(e) decanting the upper liquid phase from a lower liquid phase containing the hydrocarbon solvent, the cosolvent and the aluminum halide catalyst;
(f) adding fresh endo-hydrogenated dicyclopentadiene compound to the lower liquid phase, and optionally adding additional aluminum halide;
(g) isomerizing the fresh endo-hydrogenated dicyclopentadiene compound; and
(h) optionally repeating steps (d) through (g) one or more times, wherein the cosolvent is a linear alkyl ester of a carboxylic acid.