Patent US4297294A successfully refreshed from Google Patents.
US4297294A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for making 4,4'-methylene diphenyl diisocyanate
Assignee: Shell USA Inc
•
Filing: 1980-09-29
•
Granted: 1981-10-27
•
Expires: 2000-09-29
Abstract
Abstract A novel process for making 4,4'-methylene diphenyl diisocyanate and corresponding oligomer in improved selectivity and yield comprises condensing formaldehyde and aniline under neutral or basic conditions to yield an anil condensate, followed by reacting the anil condensate with additional aniline and a protonic salt of aniline to yield 4,4'-methylene dianiline and corresponding oligomer, then followed by conventional phosgenation.
Inventors
- 👤 Frank D. Mango
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:39
CPC Classifications
C; C07; C07C; C07C265/00; C07C265/12; C07D; C07D251/00; C07D251/02; C07D251/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
A process for the selective production of 4,4'-methylene diphenyl diisocyanate and corresponding oligomers, consisting essentially of the steps of: (a) condensing formaldehyde with aniline under neutral or basic conditions to yield an anil condensate; (b) reacting said anil condensate with aniline and a protonic salt of aniline under acidic conditions to yield an intermediate product selected from the group consisting of 4,4'-methylene dianiline, its corresponding oligomers and mixtures thereof; and (c) reacting said intermediate product with phosgene to yield the corresponding diisocyanate or polysiocyanate.
Claim 2
Dependent Claim
84 words
A process for the selective production of 4,4'-methylene diphenyl diisocyanate and corresponding oligomers, consisting essentially of the steps of: (a) condensing formaldehyde with aniline under neutral or basic conditions to yield an anil condensate; (b) reacting said anil condensate with aniline and a protonic salt of aniline under acidic conditions to yield an intermediate product selected from the group consisting of 4,4'-methylene dianiline, its corresponding oligomers and mixtures thereof; and (c) reacting said intermediate product with phosgene to yield the corresponding diisocyanate or polysiocyanate.
Claim 3
Dependent Claim
28 words
The process of claim 1 where said anil condensate is selected from the group consisting of ##STR12## and mixtures thereof where n varies from 1 to about 200.
Claim 4
Dependent Claim
13 words
The process of claim 1 wherein step a takes place under basic conditions.
Claim 5
Dependent Claim
35 words
The process of claim 1 where said protonic salt of aniline is the addition salt of aniline with an acid selected from the group consisting of hydrochloric acid, hydrobromic acid, hydrofluoric acid and sulfuric acid.
Claim 6
Dependent Claim
14 words
The process of claim 4 wherein said protonic salt of aniline is aniline hydrochloride.
Claim 7
Dependent Claim
23 words
The process of claim 1 wherein the molar ratio of aniline to formaldehyde in step a is between about 1:2 and about 3:1.
Claim 8
Dependent Claim
25 words
The process of claim 1 or 6 wherein the molar ratio of aniline to anil condensate in step b is between about 1:1 and 6:1.
Claim 9
Dependent Claim
27 words
The process of claim 7 wherein molar ratio of said protonic salt of aniline to said aniline in step b is between about 1:10 and about 1:2.
Claim 10
Dependent Claim
22 words
The process of claim 1 wherein said anil condensate is recovered from step a prior to contact with aniline in step b.
References Cited (Backward Citations)
US2818433A
Cited
US2974168A
Cited
US3676497A
Cited
GB1277740A
Cited
US3476806A
Cited
GB1365190A
Cited
GB1341018A
Cited
BE803216A
Cited
DD109615A1
Cited
BE815840A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-10-26 | 1985-04-27 | 1985-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-26 | 1989-04-27 | 1989-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-26 | 1993-04-27 | 1993-10-27 | $7700.00 | Window Closed / Lapsed |