US4294774A
Expired / Lapsed
US
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Preparation of organic isocyanates
Assignee: Dow Chemical Co
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Filing: 1980-11-14
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Granted: 1981-10-13
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Expires: 2000-11-14
Abstract
Abstract A process for the preparation of an organic isocyanate by preparing a heated solution of an alkyl carbamate in a N,N-dialkyl aniline compound solvent which is catalytic with respect to the rate of decomposition of the carbamate but unreactive with respect to the organic isocyanate decomposition product.
Inventors
- 👤 Thomas R. Henson
- 👤 John F. Timberlake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:49
CPC Classifications
C; C07; C07C; C07C263/00; C07C263/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
71 words
A process for the preparation of an organic isocyanate product comprising the step of preparing a heated solution of an alkyl carbamate in a solvent whereby the carbamate is catalytically decomposed into the corresponding organic isocyanate product and alkyl alcohol, said solvent being an N,N-dialkyl aniline compound which is characterized as being catalytic with respect to the decomposition rate of the carbamate but unreactive with respect to the organic isocyanate product.
Claim 2
Dependent Claim
71 words
A process for the preparation of an organic isocyanate product comprising the step of preparing a heated solution of an alkyl carbamate in a solvent whereby the carbamate is catalytically decomposed into the corresponding organic isocyanate product and alkyl alcohol, said solvent being an N,N-dialkyl aniline compound which is characterized as being catalytic with respect to the decomposition rate of the carbamate but unreactive with respect to the organic isocyanate product.
Claim 3
Dependent Claim
19 words
The process of claim 1, wherein the N,N-dialkyl aniline is N,N-dimethyl aniline, N,N-diethyl aniline, N-methyl-N-ethyl aniline or mixtures thereof.
Claim 4
Dependent Claim
13 words
The process of claim 2, wherein the carbamate is methylene dimethyl diphenyl carbamate.
Claim 5
Dependent Claim
35 words
The process of claim 3, wherein the heated solution is prepared by dissolving the carbamate in the solvent and then heating the solution to a temperature of between about 150° C. and about 350° C.
Claim 6
Dependent Claim
34 words
The process of claim 3, wherein the heated solution is prepared by adding the carbamate to the solvent which has been preheated to a temperature of between about 150° C. and about 350° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-10-12 | 1985-04-13 | 1985-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-12 | 1989-04-13 | 1989-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-12 | 1993-04-13 | 1993-10-13 | $7700.00 | Window Closed / Lapsed |