Granted Patent B2

US 7,294,724 · App. 11/201,528 · Granted Nov 13, 2007

Abstract

Claims (13)

1. A process for the manufacture of a fluoran dye of the structure according to formula 1

comprising condensing in an alkanesulfonic acid or in an arenesulfonic acid a keto acid according to formula 2

with an aminodiphenylamine of formula 3

wherein R, R 1 and R 2 are each independently selected from alkyl(C 1 -C 8 ), aryl or aralkyl; wherein the aromatic ring in aryl or aralkyl may be unsubstituted or substituted with alkyl(C 1 -C 8 ), alkoxy(C 1 -C 8 ), or halogen; wherein R 1 —N—R 2 may form pyrrolidinyl, piperidinyl or morpholinyl ring moieties;

wherein R 3 , R 4 , R 5 and R 6 are each independently selected from hydrogen, alkyl, cycloalkyl, alkoxy, halogen, aryl or aralkyl; wherein the aromatic ring in aryl or aralkyl may be unsubstituted or substituted with alkyl, alkoxy or halogen; the alkyl or alkoxy moieties herein being from one to eight carbons; or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6 , may form alicyclic or aromatic ring structures.

2. The process according to claim 1 wherein the keto acid is first dissolved in methanesulfonic acid.

3. The process according to claim 2 wherein dissolution is accomplished by heating to at least 30° C.

4. The process according to claim 2 wherein after dissolving the keto acid, the aminodiphenylamine is added with stirring and the reaction mixture is reacted for a time and temperature sufficient to form the fluoran of formula 1.

5. The process according to claim 4 wherein the mixture is made alkaline and the formed fluoran recovered by extraction with a solvent.

6. The process according to claim 5 wherein the solvent is toluene.

7. The process according to claim 1 wherein the alkanesulfonic acid is selected from methanesulfonic acid or ethanesulfonic acid.

8. The process according to claim 1 wherein the arenesulfonic acid is selected from benzenesulfonic acid, 1-napthalenesulfonic acid, or 2-naphthalenesulfonic acid.

9. The process according to claim 1 wherein the aminodiphenylamine is 3-methoxy-4′-dimethylaminodiphenylamine.

Assignments (25)