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US4358611A
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Preparation of 2-phenylsemicarbazides
Assignee: Shell USA Inc
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Filing: 1978-01-09
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Granted: 1982-11-09
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Expires: 1998-01-09
Abstract
Abstract 2-Phenylsemicarbazides are prepared by a multi-step process involving: (a) treating a phenylhydrazine, or salt thereof, with a chloroformate; (b) adding phosgene; (c) treating the resulting product with an amine; and (d) hydrolyzing the resulting acylated semicarbazide. The reaction can proceed through a Δ 2 -1,3,4-oxadiazolin-5-one intermediate formed with heating in step (b). Certain of the products are novel compounds.
Inventors
- 👤 Kurt H. G. Pilgram
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:13
CPC Classifications
C; C07; C07D; C07D295/00; C07D295/16; C07D295/20; C07D295/215; A; A01; A01N; A01N47/00; A01N47/08; A01N47/28; A01N47/34
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
48 words
A process for the preparation of a 2-phenylsemicarbazide which comprises the steps of (a) treating a phenylhydrazine, or salt thereof, with a chloroformate; (b) adding phosgene; (c) treating the resulting product with a secondary amine; and (d) hydrolyzing the resulting acylated semicarbazide product from (c) to a 2-phenylsemicarbazide.
Claim 2
Dependent Claim
48 words
A process for the preparation of a 2-phenylsemicarbazide which comprises the steps of (a) treating a phenylhydrazine, or salt thereof, with a chloroformate; (b) adding phosgene; (c) treating the resulting product with a secondary amine; and (d) hydrolyzing the resulting acylated semicarbazide product from (c) to a 2-phenylsemicarbazide.
Claim 3
Dependent Claim
22 words
A process according to claim 1 wherein the reactions of (a), (b) and (c) take place in the presence of a solvent.
Claim 4
Dependent Claim
15 words
A process according to claim 2 wherein the solvent is an ether or a hydrocarbon.
Claim 5
Dependent Claim
18 words
A process according to claim 1 wherein the reaction (a) takes place in the presence of a tertiary-amine.
Claim 6
Dependent Claim
27 words
A process according to claim 4 wherein the tertiary-amine is a lower alkyl tertiary amine in which each alkyl group contains from 1 to 6 carbon atoms.
Claim 7
Dependent Claim
11 words
A process according to claim 5 wherein the tertiary-amine is ethyl-diisopropylamine.
Claim 8
Dependent Claim
28 words
A process according to claim 1 wherein the secondary amine in step (c) is a dialkylamine in which each alkyl group contains from 1 to 6 carbon atoms.
Claim 9
Dependent Claim
25 words
A process according to claim 1 wherein the reaction mixture of step (b) is heated to reflux until the evolution of hydrogen chloride gas ceases.
Claim 10
Dependent Claim
19 words
A process according to claim 1 wherein the 2-phenylsemicarbazide product is 4,4-dimethyl-2-(3,4-dichlorophenyl)semicarbazide, 4,4-dimethyl-2-(3-chloro-4-fluorophenyl)semicarbazide, 4,4-dimethyl-2-(4-bromophenyl)semicarbazide, 4,4-dimethyl-2-(3-(trifluoromethyl)-4-chlorophenyl)semicarbazide, 4,4-dimethyl-2-(4-chlorophenyl)semicarbazide, 4,4-dimethyl-2-(3-(trifluoromethyl)-4-isopropoxyphenyl)semicarbazide or 4,4-dimethyl-2-(3-chloro-4-isopropoxyphenyl)semicarbazide.
Claim 11
Dependent Claim
60 words
A process for the preparation of a 2-phenylsemicarbazide which comprises treating a 4-phenyl-2-substituted-Δ 2 -1,3,4-oxadiazolin-5-one with a secondary amine HNR 1 R 2 wherein R 1 and R 2 are hydrogen, alkyl or alkylene optionally interrupted by one or more oxygen atoms and hydrolyzing the resulting reaction product in the presence of an alkaline material to produce the desired 2-phenylsemicarbazide.
Claim 12
Dependent Claim
60 words
A process for the preparation of a 2-phenylsemicarbazide which comprises treating a 4-phenyl-2-substituted-Δ 2 -1,3,4-oxadiazolin-5-one with a secondary amine HNR 1 R 2 wherein R 1 and R 2 are hydrogen, alkyl or alkylene optionally interrupted by one or more oxygen atoms and hydrolyzing the resulting reaction product in the presence of an alkaline material to produce the desired 2-phenylsemicarbazide.
Claim 13
Dependent Claim
22 words
A process according to claim 10 wherein the reaction between the oxadiazolinone and amine is conducted in the presence of a solvent.
Claim 14
Dependent Claim
25 words
A process according to claim 10 wherein the secondary amine is a dialkylamine in which each alkyl group contains from 1 to 6 carbon atoms.
Claim 15
Dependent Claim
16 words
A process according to claim 10 wherein the oxadiazolinone starting material is a 4-(3,4-disubstituted-phenyl)-2-substituted-Δ 2 -1,3,4-oxadiazolin-5-one.
Claim 16
Dependent Claim
16 words
A process according to claim 10 wherein the hydrolysis is conducted using an alkali metal hydroxide.
Claim 17
Dependent Claim
19 words
A process according to claim 10 wherein the resulting 2-phenylsemicarbazide is 4,4-dimethyl-2-(3,4-dichlorophenyl)semicarbazide, 4,4-dimethyl-2-(3-chloro-4-fluorophenyl)semicarbazide, 4,4-dimethyl-2-(4-chlorophenyl)semicarbazide, 4,4-dimethyl-2-(3-trifluoromethyl)-4-chlorophenyl)semicarbazide, 4,4-dimethyl-2-(4-bromophenyl)semicarbazide, 4,4-dimethyl-2-(3-(trifluoromethyl)-4-isopropoxyphenyl)semicarbazide or 4,4-dimethyl-2-(3-chloro-4-isopropoxyphenyl)semicarbazide.
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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) | 1985-11-08 | 1986-05-10 | 1986-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-08 | 1990-05-10 | 1990-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-08 | 1994-05-10 | 1994-11-09 | $7700.00 | Window Closed / Lapsed |