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US4699994A
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Method of manufacturing diphenylmethane dicarbamic acid diesters
Assignee: JFE Engineering Corp
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Filing: 1986-09-08
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Granted: 1987-10-13
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Expires: 2006-09-08
Abstract
Abstract According to a method of manufacturing a diphenylmethane dicarbamic acid ester by reacting an N-phenyl carbamic acid diester with a methylating agent in an aqueous acid solution, the aqueous acid solution is an aqueous inorganic acid solution, and the concentration of the N-phenyl carbamic acid ester in the aqueous acid solution is not more than the solubility thereof at the reaction temperature.
Inventors
- 👤 Takao Ikariya
- 👤 Masanori Itagaki
- 👤 Masatsugu Mizuguchi
- 👤 Itaru Sakai
- 👤 Osamu Tajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:08
CPC Classifications
C; C07; C07C; C07C269/00; C07C269/06; C07C271/00; C07C271/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
75 words
A method of producing a diphenylmethane dicarbamic acid diester with a recovery of at least 72%, comprising reacting an N-phenyl carbamic acid ester with a methylating agent in an aqueous inorganic acid solution to form said diphenyldicarbamic acid diester and, during the reaction preventing the formation of a suspension of N-phenylcarbamic acid ester in the mixture by maintaining the concentration of N-phenylcarbamic acid ester at not more than the solubility thereof at the reaction temperature.
Claim 2
Independent Claim
75 words
A method of producing a diphenylmethane dicarbamic acid diester with a recovery of at least 72%, comprising reacting an N-phenyl carbamic acid ester with a methylating agent in an aqueous inorganic acid solution to form said diphenyldicarbamic acid diester and, during the reaction preventing the formation of a suspension of N-phenylcarbamic acid ester in the mixture by maintaining the concentration of N-phenylcarbamic acid ester at not more than the solubility thereof at the reaction temperature.
Claim 3
Dependent Claim
48 words
A method according to claim 1 wherein the given aqueous inorganic acid solution is such that a ratio of the solubility of the N-phenyl carbamic acid ester as a starting material to the solubility of the diphenylmethane dicarbamic acid diester as a product is not more than 0.1.
Claim 4
Dependent Claim
21 words
A method according to claim 1 wherein the concentration of the aqueous inorganic acid solution is 1 to 80% by weight.
Claim 5
Dependent Claim
20 words
A method according to claim 1 wherein the reaction temperature falls within a range of 20° C. to 150° C.
Claim 6
Dependent Claim
20 words
A method according to claim 1 wherein the reaction temperature falls wtihin a range of 50° C. to 120° C.
Claim 7
Dependent Claim
72 words
The method of claim 1 wherein, in the aqueous inorganic acid solution, the ratio of the solubility of the N-phenyl carbamic acid ester as a starting material to the solubility of the diphenylmethane dicarbamic acid ester as a product is not more than 0.1; the concentration of the aqueous inorganic acid solution is 1 to 80% by weight; and the reaction temperature falls within a range of 20° C. to 150° C.
Claim 8
Dependent Claim
58 words
The method of claim 6 wherein the aqueous inorganic acid solution contains hydrochloric or sulphuric acid as the inorganic acid; the N-phenyl carbamic acid ester is ##STR2## wherein R 1 is an alkyl, an alicylic or an aromatic group; each R 2 is individually selected from hydrogen, alkyl, halogen, nitro or alkoxyl and n is 0 to 4.
Claim 9
Dependent Claim
71 words
The method of claim 6 wherein the N-phenyl carbamic acid ester is selected from the group consisting of N-phenyl carbamic acid methyl, N-phenyl carbamic acid ethyl, N-phenyl carbamic acid n-propyl, N-phenyl carbamic acid isopropyl, N-phenyl carbamic acid phenyl, N-phenyl carbamic acid cyclohexyl, N-o-chlorophenyl carbamic acid methyl, N-m-chlorophenyl carbamic acid methyl, N-o-methylphenyl carbamic acid methyl, N-m-methyl carbamic acid methyl, N-2,6-dimethyl carbamic acid methyl, N-o-nitrophenyl carbamic acid methyl, and N-o-methoxy carbamic acid methyl.
Claim 10
Dependent Claim
40 words
The method of claim 8 wherein the methylating agent is formaldehyde, or a material for generating formaldehyde under reaction conditions of the method, used in an equivalent amount of 0.5 to 10 with respect to the N-phenyl carbamic acid ester.
Claim 11
Dependent Claim
15 words
The method of claim 6 wherein the N-phenyl carbamic acid ester is PhNHCOOMe or PhNHCOOEt.
Claim 12
Dependent Claim
15 words
The method of claim 1 wherein the N-phenyl carbamic acid ester is PhNHCOOMe or PhNHCOOEt.
References Cited (Backward Citations)
CA1120051A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-12 | 1991-04-13 | 1991-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-12 | 1995-04-13 | 1995-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-12 | 1999-04-13 | 1999-10-13 | $7700.00 | Window Closed / Lapsed |