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US4851603A
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Preparation of cyclobutarenes via the steam pyrolysis of aromatic derivatives
Assignee: Dow Chemical Co
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Filing: 1987-10-23
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Granted: 1989-07-25
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Expires: 2007-10-23
Abstract
Abstract Cyclobutarenes are prepared by pyrolyzing a suitable benzene, naphthalene, or pyridine derivative in the presence of an amount of steam effective to substantially reduce the partial pressure of the pyrolyzing compound.
Inventors
- 👤 George J. Quarderer
- 👤 Fred C. Stone
- 👤 Mark J. Beitz
- 👤 Patrick M. O'Donnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:45
CPC Classifications
C; C07; C07C; C07C13/00; C07C13/28; C07C13/32; C07C1/00; C07C1/26; C07C1/28; C07C1/20; C07C2602/00; C07C2602/02; C07C2602/04; C07C2602/06
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
66 words
An improved process of preparing a cyclobutarene by pyrolyzing a benzene or a naphthalene substituted with any of halomethyl, hydroxymethyl, acetoxymethyl, or trifluoroacetoxymethyl and either methyl or substituted methyl ortho thereto having at least one hydrogen on the alpha carbon; wherein the improvement comprises conducting the pyrolysis in the presence of an amount of steam effective to substantially reduce the partial pressure of the pyrolyzing compound.
Claim 2
Dependent Claim
66 words
An improved process of preparing a cyclobutarene by pyrolyzing a benzene or a naphthalene substituted with any of halomethyl, hydroxymethyl, acetoxymethyl, or trifluoroacetoxymethyl and either methyl or substituted methyl ortho thereto having at least one hydrogen on the alpha carbon; wherein the improvement comprises conducting the pyrolysis in the presence of an amount of steam effective to substantially reduce the partial pressure of the pyrolyzing compound.
Claim 3
Dependent Claim
9 words
The process of claim 1 wherein halomethyl is chloromethyl.
Claim 4
Dependent Claim
13 words
The process of claim 1 wherein substituted methyl is lower alkyl or halomethyl.
Claim 5
Dependent Claim
9 words
The process of claim 3 wherein halomethyl is chloromethyl.
Claim 6
Dependent Claim
26 words
The process of claim 1 wherein the aromatic ring of the pyrolyzing compound is further substituted with at least one substituent stable to the pyrolysis conditions.
Claim 7
Dependent Claim
18 words
The process of claim 5 wherein the stable group is methyl, methoxy, methoxycarbonyl, nitro, chloro, bromo, or iodo.
Claim 8
Dependent Claim
17 words
The process of claim 1 wherein the cyclobutarene prepared is benzocyclobutene and the pyrolyzing compound is α-chloro-ortho-xylene.
Claim 9
Dependent Claim
17 words
The process of claim 1 wherein the α-chloro-ortho-xylene is prepared in situ by reacting ortho-xylene with chlorine.
Claim 10
Dependent Claim
21 words
The process of claim 1 wherein the mole ratio of steam to pyrolyzing compound ranges from about 5:1 to about 100:1.
Claim 11
Dependent Claim
21 words
The process of claim 9 wherein the mole ratio of steam to pyrolyzing compound ranges from about 19:1 to about 40:1.
Claim 12
Dependent Claim
18 words
The process of claim 1 wherein the reaction temperature ranges from about 400° C. to about 800° C.
Claim 13
Dependent Claim
18 words
The process of claim 11 wherein the reaction temperature ranges from about 550° C. to about 700° C.
Claim 14
Dependent Claim
18 words
The process of claim 1 wherein the total reaction pressure ranges from about 0.1 atmosphere to substantially atmospheric.
Claim 15
Dependent Claim
13 words
The process of claim 13 wherein the total reaction pressure is substantially atmospheric.
Claim 16
Dependent Claim
22 words
The process of claim 1 wherein the pyrolysis occurs in a tubular reactor with a length to diameter ratio greater than 10:1.
Claim 17
Dependent Claim
20 words
The process of claim 15 wherein the pyrolyzing compound is vaporized and combined with the steam before entering the reactor.
Claim 18
Dependent Claim
17 words
The method of claim 15 wherein the reactor is heated in a fluidized bed of fine powder.
Claim 19
Dependent Claim
27 words
The method of claim 15 wherein the pyrolyzing compound is vaporized and preheated with the steam to near reaction temperature in a preheater before entering the reactor.
Claim 20
Dependent Claim
17 words
The process of claim 1 wherein the yield of the cyclobutarene prepared is greater than 20 percent.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-24 | 1993-01-23 | 1993-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-24 | 1997-01-23 | 1997-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-24 | 2001-01-23 | 2001-07-25 | $7700.00 | Window Closed / Lapsed |