Process for producing ester compound

1. A method for producing an ester compound having a heterocyclic group(s) which comprises:

subjecting a carboxylic acid and an alcohol to a dehydration-condensation reaction with adding no solvent or with adding a nonaqueous solvent into a reaction system, in a presence of an involatile acid catalyst;

then removing a residue of the acid catalyst without adding any solvent or in a nonaqueous solvent by bringing a weak basic substance into contact with the residual acid catalyst, forming a salt of the weak basic substance and the acid catalyst, and then filtering off the salt,

wherein the carboxylic acid is a compound represented by a formula (2):

R 2 —COOH  (2),

wherein R 2 represents an alkyl group having 1 to 18 carbon atoms, an oxygen-atom-containing alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a heterocyclic group, which may have a substituent; and

the alcohol is a compound represented by a formula (1):

R 1 —OH  (1),

wherein R 1 represents an alkyl group having 1 to 18 carbon atoms, an oxygen-atom-containing alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a heterocyclic group, which may have a substituent; and

wherein the heterocyclic group represented by R 1 and R 2 is 5-membered ring or a 6-membered ring, which has 1 to 3 hetero atoms selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom,

the substituent of the alkyl group, the alkenyl group, or the alkynyl group represented by R 1 and R 2 is selected from the group consisting of a halogen atom, a haloalkyl group, an alkoxy group, a haloalkoxy group, a thioalkoxy group, an acyl group, a substituted amino group, a hydroxyl group, a cyano group, a carboxyl group, a nitrile group, and a nitro group, and

the substituent of the aryl group, the aralkyl group, or the heterocyclic group represented by R 1 and R 2 is selected from the group consisting of a halogen atom, an alkyl group, a haloalkyl group, an alkenyl group, an alkoxy group, a haloalkoxy group, a thioalkoxy group, an acyl group, a substituted amino group, a hydroxyl group, a cyano group, a carboxyl group, a nitrile group, and a nitro group; and

the ester compound obtained from the above carboxylic acid of the formula (2) and the above alcohol of the formula (1) is a compound represented by a formula (3):

R 1 —OCO—R 2   (3)

wherein R 1 and R 2 are same as the above, wherein at least one of R 1 and R 2 is the heterocyclic group.

2. The method according to claim 1 , wherein a dehydration treatment is carried out during the dehydration-condensation reaction.

3. The method according to claim 1 , wherein the weak basic substance is

a) an inorganic weak base,

b) an amine compound represented by a formula (5):

wherein R 4 to R 6 are each independently

a hydrogen atom,

an alkyl group, which may have a substituent, wherein the substituent of the alkyl group is alkyl-substituted amino group, which is an amino group in which the hydrogen atom is substituted with an alkyl group having 1 to 3 carbon atoms,

an aryl group, or an aralkyl group, and

wherein the R 4 to R 6 may form a heterocycle group with the R 4 to R 6 and a nitrogen atom binding to them, wherein at least one of R 4 to R 6 is an alkyl group, an aryl group, or an aralkyl group, or the R 4 to R 6 form the heterocycle group with the nitrogen atom binding to them,

c) 1,8-diazabicyclo[5.4.0]undeca-7-ene, or

d) 1,4-diazabicyclo[2.2.2]octane.

4. The method according to claim 1 , wherein the weak basic substance is triethylamine or pyridine.

5. The method according to claim 1 , wherein the involatile acid catalyst is a sulfuric acid or a sulfonic acid represented by a formula (4):

R 3 —SO 3 H  (4),

wherein R 3 is an alkyl group, an aryl group, or an aralkyl group, which may have a substituent,

wherein the substituent of the alkyl group, the aryl group, or the aralkyl group is selected from the group consisting of a halogen atom, an alkyl group, and a haloalkyl group.

6. The method according to claim 5 , wherein said acid catalyst is sulfuric acid or p-toluenesulfonic acid.

7. The method according to claim 1 , wherein the nonaqueous solvent is toluene, dichloromethane or cyclohexane.

8. The method according to claim 1 , wherein the filtering treatment is carried out by using a filter aid.

9. The method according to claim 8 , wherein the filter aid is diatomaceous earth, silica gel, activated carbon, hydroxyapatite, alumina, or alumina silica.

10. The method according to claim 2 , wherein the dehydration treatment is a reflux dehydration treatment.

11. The method according to claim 2 , wherein the dehydration treatment is an adsorption dehydration treatment.

12. The method according to claim 1 , wherein a polymerization inhibitor further is present in the dehydration-condensation reaction when at least one of R 1 and R 2 is an alkenyl group or an alkynyl group.

13. The method according to claim 12 , wherein the polymerization inhibitor is at least one inhibitor selected from the group consisting of tert-butyl catechol, hydroquinone, 2,6-di-tert-butyl-4-methylphenol, methylhydroquinone, and phenothiazine.

14. A method for producing an ester compound having a heterocyclic group(s), which comprises:

subjecting a carboxylic acid having an alcohol moiety to a dehydration-condensation reaction with adding no solvent or with adding a nonaqueous solvent into a reaction system, in a presence of involatile acid catalyst;

then removing a residue of the acid catalyst without adding any solvent or in a nonaqueous solvent by bringing a weak basic substance into contact with the residual acid catalyst, forming a salt of the weak basic substance and the acid catalyst, and then filtering off the salt,

wherein the carboxylic acid having an alcohol moiety is a compound represented by a formula (7):

wherein T is an alkylene chain, which may have a substituent,

wherein the substituent of the alkylene chain is selected from the group consisting of a halogen atom, a haloalkyl group, an alkoxy group, a haloalkoxy group, a thioalkoxy group, an acyl group, a substituted amino group, a hydroxyl group, a cyano group, a carboxyl group, a nitrile group, and a nitro group, and

the ester compound obtained from the above compound of the formula (7) is a compound represented by a formula (8):

wherein T is same as above.

15. The method according to claim 1 , wherein R 1 is the heterocyclic group.

16. The method according to claim 1 , wherein R 2 is the heterocyclic group.

17. The method according to claim 1 , wherein the both of R 1 and R 2 are the heterocyclic group.

18. The method according to claim 1 , wherein the heterocyclic group represented by R 1 and R 2 is a pyrrolidyl-2-one group, a piperidyl group, a piperidino group, a piperazinyl group, a morpholino group, a pyridyl group, an imidazolyl group, a thiazoly group, a furyl group, or a pyranyl group.

19. The method according to claim 14 , wherein the weak basic substance is

a) an inorganic weak base,

b) an amine compound represented by a formula (5):

wherein R 4 to R 6 are each independently a hydrogen atom, an alkyl group, which may have a substituent, wherein the substituent of the alkyl group is alkyl-substituted amino group, which is an amino group in which the hydrogen atom is substituted with an alkyl group having 1 to 3 carbon atoms, an aryl group, or an aralkyl group, and

wherein the R 4 to R 6 may form a heterocycle group with the R 4 to R 6 and a nitrogen atom binding to them, wherein at least one of R 4 to R 6 is an alkyl group, an aryl group, or an aralkyl group, or the R 4 to R 6 form the heterocycle group with the nitrogen atom binding to them,

c) 1,8-diazabicyclo[5.4.0]undeca-7-ene, or

d) 1,4-diazabicyclo[2.2.2]octane.