US4123450A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing alkyl isocyanates
Assignee: FMC Corp
•
Filing: 1977-09-22
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Granted: 1978-10-31
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Expires: 1997-09-22
Abstract
Abstract Alkylisocyanates are prepared by reacting a phenol or substituted phenol and phosgene in a halogenated hydrocarbon solvent with aqueous alkali metal hydroxide to produce a corresponding chloroformate, reacting the resulting chloroformate solution with aqueous alkylamine to give a corresponding N-alkylcarbamate which, after solvent is stripped, is then pyrolyzed to yield the alkyl isocyanate. Solvent and the starting phenol may be recovered and recycled to the process.
Inventors
- 👤 Harry W. Weber, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:16
CPC Classifications
C; C07; C07C; C07C68/00; C07C68/02; C07C263/00; C07C263/04; C07C269/00; C07C269/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
155 words
A process for producing an alkyl isocyanate which comprises: (1) reacting a hydroxybenzene of the formula ##STR4## wherein R is hydrogen or lower alkyl of 1 or 2 carbon atoms, and phosgene in a halogenated hydrocarbon solvent with an aqueous alkali metal hydroxide, permitting the aqueous and organic phases to separate, removing the aqueous phase and recovering the organic phase comprising a solution of the corresponding chloroformate in said solvent, (2) reacting the organic phase recovered from step 1, in the presence of an alkali metal hydroxide, with an alkylamine in which the alkyl group corresponds to the alkyl group of the alkyl isocyanate, allowing the aqueous and organic phases to separate, and recovering the organic phase comprising a solution of the corresponding N-alkylcarbamate in said solvent, (3) stripping said solvent from the organic phase resulting from step (2), (4) pyrolyzing the bottoms product of step (3) and selectively condensing and collecting said alkyl isocyanate.
Claim 2
Dependent Claim
155 words
A process for producing an alkyl isocyanate which comprises: (1) reacting a hydroxybenzene of the formula ##STR4## wherein R is hydrogen or lower alkyl of 1 or 2 carbon atoms, and phosgene in a halogenated hydrocarbon solvent with an aqueous alkali metal hydroxide, permitting the aqueous and organic phases to separate, removing the aqueous phase and recovering the organic phase comprising a solution of the corresponding chloroformate in said solvent, (2) reacting the organic phase recovered from step 1, in the presence of an alkali metal hydroxide, with an alkylamine in which the alkyl group corresponds to the alkyl group of the alkyl isocyanate, allowing the aqueous and organic phases to separate, and recovering the organic phase comprising a solution of the corresponding N-alkylcarbamate in said solvent, (3) stripping said solvent from the organic phase resulting from step (2), (4) pyrolyzing the bottoms product of step (3) and selectively condensing and collecting said alkyl isocyanate.
Claim 3
Dependent Claim
29 words
The process of claim 1 including the additional step of stripping said hydroxybenzene from the bottoms product of step 4 and recycling the resulting residual carbamate to step 4.
Claim 4
Dependent Claim
18 words
The process of claim 2 wherein solvent from step 3 and said hydroxybenzene are recycled to step (1).
Claim 5
Dependent Claim
25 words
The process of claim 1 wherein said alkyl isocyanate is a lower alkyl isocyanate in which the alkyl group has 1 to 4 carbon atoms.
Claim 6
Dependent Claim
12 words
The process of claim 4 wherein said alkyl isocyanate is methyl isocyanate.
Claim 7
Dependent Claim
10 words
The process of claim 1 wherein said hydroxybenzene is phenol.
Claim 8
Dependent Claim
12 words
The process of claim 1 wherein said halogenated hydrocarbon is methylene chloride.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-30 | 1982-05-01 | 1982-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-30 | 1986-05-01 | 1986-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-30 | 1990-05-01 | 1990-10-31 | $7700.00 | Window Closed / Lapsed |