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US4390692A
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Trimethylsilylation of cellulose
Assignee: Dow Chemical Co
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Filing: 1982-06-21
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Granted: 1983-06-28
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Expires: 2002-06-21
Abstract
Abstract This invention provides a method for the preparation of trimethylsilyl cellulose ethers. The method comprises reacting cellulose with hexamethyldisilazane in the presence of a small amount of catalyst, wherein the catalyst is acetamide, acetamide and an ammonium halide, N,N-dimethylformamide and an ammonium halide, N,N-dimethylformamide and trimethylsilyl chloride, 2-oxazolidinone and an ammonium halide, or a mixture thereof.
Inventors
- 👤 John G. Green
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:19
CPC Classifications
C; C08; C08B; C08B11/00; C08B15/00; C08B15/05
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
52 words
A method for the preparation of trimethylsilyl cellulose ethers, which comprises reacting cellulose with hexamethyldisilazane in the presence of a small amount of catalyst, wherein the catalyst is acetamide, acetamide and an ammonium halide, N,N-dimethylformamide and an ammonium halide, N,N-dimethylformamide and trimethylsilyl chloride, 2-oxazolidinone and an ammonium halide, or a mixture thereof.
Claim 2
Independent Claim
52 words
A method for the preparation of trimethylsilyl cellulose ethers, which comprises reacting cellulose with hexamethyldisilazane in the presence of a small amount of catalyst, wherein the catalyst is acetamide, acetamide and an ammonium halide, N,N-dimethylformamide and an ammonium halide, N,N-dimethylformamide and trimethylsilyl chloride, 2-oxazolidinone and an ammonium halide, or a mixture thereof.
Claim 3
Dependent Claim
19 words
The method of claim 1, wherein the reaction is carried out between about 100° C. and about 135° C.
Claim 4
Dependent Claim
19 words
The method of claim 2, wherein the reaction is carried out between about 105° C. and about 115° C.
Claim 5
Dependent Claim
12 words
The method of claim 3, wherein the ammonium halide is ammonium chloride.
Claim 6
Dependent Claim
13 words
The method of claim 4, wherein the catalyst is N,N-dimethylformamide and ammonium chloride.
Claim 7
Dependent Claim
22 words
The method of claim 5, wherein the amount of N,N-dimethylformamide is between about 0.07 and about 0.4 grams per gram of cellulose.
Claim 8
Dependent Claim
22 words
The method of claim 6, wherein the amount of N,N-dimethylformamide is between about 0.1 and about 0.2 grams per gram of cellulose.
Claim 9
Dependent Claim
23 words
The method of claim 7, wherein the amount of ammonium chloride is between about 0.05 and about 0.1 grams per gram of cellulose.
Claim 10
Dependent Claim
23 words
The method of claim 8, wherein the amount of ammonium chloride is between about 0.05 and about 0.07 grams per gram of cellulose.
Claim 11
Dependent Claim
24 words
The method of claim 9, wherein the weight ratio of hexamethyldisilazane to N,N-dimethylformamide is between about ten to one and about twenty to one.
Claim 12
Dependent Claim
26 words
The method of claim 10, wherein the mole ratio of hexamethyldisilazane to cellulose anhydroglucose units is between about two to one and about four to one.
References Cited (Backward Citations)
US2562955A
Cited
US2782090A
Cited
US2824778A
Cited
US3393218A
Cited
US3418313A
Cited
US3418312A
Cited
US3432488A
Cited
US4337095A
Cited
AT364859B
Cited
AT364860B
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-27 | 1986-12-27 | 1987-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-27 | 1990-12-27 | 1991-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-27 | 1994-12-27 | 1995-06-28 | $7700.00 | Window Closed / Lapsed |