Patent US4348533A successfully refreshed from Google Patents.
US4348533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of linear polydimethylsiloxanes
Assignee: Dow Silicones Corp
•
Filing: 1981-10-13
•
Granted: 1982-09-07
•
Expires: 2001-10-13
Abstract
Abstract High yields of linear dimethylpolysiloxanes are obtained by reacting dimethyldichlorosilane with methanol in contact with certain quarternary ammonium halides, such as methyl pyridinium chloride, at a pressure of 15 to 100 psi.
Inventors
- 👤 Allan M. Alanko
- 👤 David R. Salverson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:31
CPC Classifications
C; C08; C08G; C08G77/00; C08G77/04; C08G77/06; C08G77/08
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
156 words
In a method of producing linear polysiloxanes by reaction of dimethyldichlorosilane and methanol in contact with a catalyst selected from the group consisting of (1) pyridinium chlorides of the formula ##STR3## (2) compounds of the formula R'" 4 N + Cl - , ##STR4## where R' is a hydrocarbon radical having 18 or less carbon atoms; "a" is an integer from 0-5; "m" is an integer greater than 1, R" is a lower alkyl radical; and R'" is selected from the group consisting of methyl, hydroxy alkyl of 2-4 inclusive carbon atoms, aromatic hydrocarbon radicals, and ArCH 2 -- radicals in which Ar is an aromatic hydrocarbon radical there being no more than 18 carbon atoms total in the R'" group, the improvement comprising carrying out the reaction at a pressure of from 15 to 100 psi at a temperature of from 130° to 170° C. and thereafter separating the dimethylpolysiloxane so produced from the catalyst.
Claim 2
Dependent Claim
156 words
In a method of producing linear polysiloxanes by reaction of dimethyldichlorosilane and methanol in contact with a catalyst selected from the group consisting of (1) pyridinium chlorides of the formula ##STR3## (2) compounds of the formula R'" 4 N + Cl - , ##STR4## where R' is a hydrocarbon radical having 18 or less carbon atoms; "a" is an integer from 0-5; "m" is an integer greater than 1, R" is a lower alkyl radical; and R'" is selected from the group consisting of methyl, hydroxy alkyl of 2-4 inclusive carbon atoms, aromatic hydrocarbon radicals, and ArCH 2 -- radicals in which Ar is an aromatic hydrocarbon radical there being no more than 18 carbon atoms total in the R'" group, the improvement comprising carrying out the reaction at a pressure of from 15 to 100 psi at a temperature of from 130° to 170° C. and thereafter separating the dimethylpolysiloxane so produced from the catalyst.
Claim 3
Dependent Claim
14 words
The method of claim 1 in which the catalyst is in the molten condition.
Claim 4
Dependent Claim
12 words
The method of claim 2 in which the catalyst is methylpyridinium chloride.
Claim 5
Independent Claim
24 words
The method of claims 1, 2, and 3 in which the methanol is employed in amount of from 5 to 10 mol percent excess.
References Cited (Backward Citations)
US4108882A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-06 | 1986-03-08 | 1986-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-06 | 1990-03-08 | 1990-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-06 | 1994-03-08 | 1994-09-07 | $7700.00 | Window Closed / Lapsed |