Patents by Inventor David Y. Tang

David Y. Tang has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6284934
    Abstract: Disclosed is a method of separating the meta isomer of a haloalkylbenzene having the general formula from a mixture with at least one other isomer, where X is Cl or Br and R is alkyl from C2 to C12 or cycloalkyl from C3 to C8. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst is added to the mixture and the mixture is exposed to a brominating agent which preferentially brominates the meta isomer. The mixture is then heated at a temperature above the boiling point of the other isomers but below the boiling point of the brominated meta isomer.
    Type: Grant
    Filed: January 10, 2000
    Date of Patent: September 4, 2001
    Assignee: Occidental Chemical Corporation
    Inventors: Michael J. Fifolt, William S. Derwin, Viesturs Lesins, Arthur H. Morth, Frank P. Bermel, David Y. Tang, Mark E. Lindrose, William L. Rueter
  • Patent number: 6156945
    Abstract: Disclosed is a method of making high purity 2,4- and 3,4-dichlorotoluene from parachlorotoluene that contains some metachlorotoluene. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst and about 0.5 to about 10 equivalents of a brominating agent are added to the parachlorotoluene. The metachlorotoluene is brominated, but most of the parachlorotoluene is not brominated. Without separating the brominated products from the unbrominated products, about 0.5 to about 1.5 equivalents of a chlorinating agent are added, whereby only the unbrominated products (i.e., the parachlorotoluene) are chlorinated. The resulting 2,4-dichlorotoluene and 3,4-dichlorotoluene can be separated by distillation.
    Type: Grant
    Filed: October 28, 1999
    Date of Patent: December 5, 2000
    Assignee: Occidental Chemical Corporation
    Inventors: Viesturs Lesins, Arthur H. Morth, Frank P. Bermel, David Y. Tang, Mark E. Lindrose, William L. Rueter, Dean R. Lagerwall, Pravin M. Khandare, Hang-Chang Bobby Chen, Mark F. Lechner
  • Patent number: 6153810
    Abstract: Disclosed is a method of making an o-arylbenzonitrile by reacting o-chlorobenzonitrile with a substituted phenylzinc halide. The reaction is performed in the presence of a nickel catalyst, an ethereal solvent, and N-methylpyrrolidinone as a cosolvent.
    Type: Grant
    Filed: April 30, 1998
    Date of Patent: November 28, 2000
    Assignee: Occidental Chemical Corporation
    Inventors: Bao-Guo Huang, David Y. Tang
  • Patent number: 6130361
    Abstract: Disclosed is a method of separating the meta isomer of a halotoluene having the general formula ##STR1## from a mixture with at least one other isomer, where X is Cl or Br. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst is added to the mixture and the mixture is exposed to a brominating agent which preferentially brominates the meta isomer. The mixture is then heated at a temperature above the boiling point of the other isomers but below the boiling point of the brominated meta isomer.
    Type: Grant
    Filed: November 17, 1998
    Date of Patent: October 10, 2000
    Assignee: Occidental Chemical Corporation
    Inventors: Viesturs Lesins, David Y. Tang, Arthur H. Morth, Mark E. Lindrose, William L. Rueter, Frank Bermel
  • Patent number: 5998670
    Abstract: Disclosed is a method of making a substituted diphenyldisulfide from a substituted thiophenol. A two phase reaction mixture is prepared which comprises a substituted thiophenol having the general formula ##STR1## hydrogen peroxide, water, an organic solvent, a basic salt that will give a pH between about 7 and about 10, and an optional flocculating agent. In the formula, R is selected from the group consisting of halogen, alkyl from C.sub.1 to C.sub.6, alkoxy from C.sub.1 to C.sub.6, or nitro. After the exothermic reaction is complete, the reaction mixture is cooled to crystallize the substituted diphenyldisulfide product. The symmetrical product precipitates preferentially over the unsymmetrical product, thereby enhancing the purity of the product over the purity of the starting material. Optionally, the organic solvent and the aqueous phase are recycled.
    Type: Grant
    Filed: March 18, 1998
    Date of Patent: December 7, 1999
    Assignee: Occidental Chemical Corporation
    Inventors: David Y. Tang, Michael C. Hausladen, Viktor D. Sorokin
  • Patent number: 5935372
    Abstract: Disclosed is a blend capable of forming a semi-interpenetrating network when cured of (A) a solution of about 30 to about 50 wt % solids in an organic solvent of a fully imidized polyimidesiloxane and (B) about 5 to about 30 pbw per 100 pbw of the polyimidesiloxane of an epoxy resin which comprises a cycloaliphatic epoxy and an epoxy curing agent. The polyimidesiloxane is the reaction product of an aromatic dianhydride and diamine. The diamine is about 5 to about 80 mole % non-siloxane containing aromatic diamine and the remainder a siloxane diamine, where the siloxane diamine is about 40 to about 80 wt % of the weight of the polyimidesiloxane. The blend is used to bond metal parts to ceramic packages.
    Type: Grant
    Filed: April 29, 1997
    Date of Patent: August 10, 1999
    Assignee: Occidental Chemical Corporation
    Inventors: Sergio Rojstaczer, David Y. Tang, Jerald C. Rosenfeld
  • Patent number: 5874606
    Abstract: Disclosed is a method of making an o-arylbenzonitrile. A mixture is prepared of o-chlorobenzonitrile and about 1.0 to about 2.0 equivalents per equivalent of o-chlorobenzonitrile of a substituted phenylmagnesium halide in about 5 to about 30 mL per gram of o-chlorobenzonitrile of a solvent system of an ethereal solvent and N-methyl pyrrolidinone. The o-chlorobenzonitrile is reacted with the substituted phenylmagnesium halide at a temperature of about 10-.degree. to about 25.degree. C.
    Type: Grant
    Filed: March 31, 1998
    Date of Patent: February 23, 1999
    Assignee: Occidental Chemical Corporation
    Inventors: Bao-Guo Huang, David Y. Tang
  • Patent number: 5866709
    Abstract: Disclosed is a process for making an aromatic nitrile by reacting a benzotrichloride with an ammonium halide in the presence of an oxygen-donating initiator at a temperature of about 150.degree. to about 250.degree. C. An optional catalyst of a metal oxide or a metal salt can be used if desired.
    Type: Grant
    Filed: December 2, 1997
    Date of Patent: February 2, 1999
    Assignee: Occidental Chemical Corp
    Inventors: Michael C. Hausladen, Bao-Guo Huang, David Y. Tang
  • Patent number: 5317049
    Abstract: Disclosed is a solution which comprises(a) a substantially fully imidized polyimidesiloxane; and(b) a solvent which comprises at least 50 wt % of a substituted pyrrolidone having the general formula ##STR1## where R is aliphatic or cycloaliphatic from C.sub.3 to C.sub.10. Also disclosed is a method of forming a coating on a substrate by applying the solution to the substrate and evaporating the solvent. Coatings formed from this solution are not subject to whitening as are coatings formed from the same polymers in other solvents.
    Type: Grant
    Filed: June 21, 1993
    Date of Patent: May 31, 1994
    Assignee: Occidental Chemical Corporation
    Inventors: Sergio R. Rojstaczer, David Y. Tang, John A. Tyrell
  • Patent number: 5233054
    Abstract: Halophthalic anhydrides are prepared by the liquid phase reaction of a brominating agent with halogen substituted hexa- or tetra-hydrophthalic anhydrides.
    Type: Grant
    Filed: June 26, 1991
    Date of Patent: August 3, 1993
    Assignee: Occidental Chemical Corporation
    Inventors: David Y. Tang, Mary K. Cocoman, Harry E. Buckholtz
  • Patent number: 5206391
    Abstract: A process for the preparation of a halophthalic anhydride, such as chlorophthalic anhydride, comprising the liquid phase reaction of bromine with a halogen substituted hexa- or tetra-hydrophthalic anhydride to produce halophthalic anhydride and gaseous HBr, and reacting the gaseous HBr with chlorine to regenerate bromine.
    Type: Grant
    Filed: August 29, 1991
    Date of Patent: April 27, 1993
    Assignee: Occidental Chemical Corporation
    Inventors: Karl W. Seper, Edward J. Colman, David Y. Tang, Mary K. Cocoman, Harry E. Buckholtz
  • Patent number: 5177181
    Abstract: Disclosed is an aromatic diamine having the general formula ##STR1## where A is a group containing at least one aromatic ring, each Y is independently selected from ##STR2## R is a group containing at least one olefinically unsaturated group, R' is hydrogen, alkyl to C.sub.25, aryl, or R, n is 1 to 4, and the number of olefinic groups in Y is at least 3 when each Y is ##STR3## and otherwise is at least 2. Photosensitive polyamic acids and polyimides can be prepared from the aromatic diamines which can be crosslinked with light to a mask to form patterns on a substrate.
    Type: Grant
    Filed: June 6, 1991
    Date of Patent: January 5, 1993
    Assignee: Occidental Chemical Corporation
    Inventors: Jerold Rosenfeld, Jin-O Choi, David Y. Tang, John Tyrell
  • Patent number: 5049682
    Abstract: Halophthalic anhydrides are prepared by the liquid phase reaction of a brominating agent with halogen substituted hexa- or tetra-hydrophthalic anhydrides.
    Type: Grant
    Filed: September 11, 1989
    Date of Patent: September 17, 1991
    Assignee: Occidental Chemical Corporation
    Inventors: David Y. Tang, Mary K. Cocoman, Harry E. Buckholtz
  • Patent number: 4968830
    Abstract: Halogen substituted aromatic compounds of the formula ##STR1## wherein Y is selected from the group CO.sub.2 H, COF, COCl, COBr, CF.sub.3, CN, NCO, or F, and X and X' are independently hydrogen or a halogen selected from the group F-, Cl- and Br-, at least one of X and X' being halogen; may be prepared by the liquid phase reaction of a brominating agent, at temperatures below about 190.degree. Celsius, with a correspondingly substituted cyclohexene or cyclohexadiene.
    Type: Grant
    Filed: September 11, 1989
    Date of Patent: November 6, 1990
    Assignee: Occidental Chemical Corporation
    Inventor: David Y. Tang
  • Patent number: 4952719
    Abstract: A process for the preparation of 3-chloro-4,5-difluorobenzonitrile comprising the steps of(a) reacting an alkali metal fluoride with 4-chloro-3,5-dinitrobenzonitrile to form a 4-fluoro-3,5-dinitrobenzonitrile product;(b) chlorodenitrating the 4-fluoro product of step (a) to form the corresponding 3,5-dichloro-4-fluorobenzonitrile compound; and(c) reacting the 3,5-dichloro-4-fluorobenzonitrile compound prepared in step (b) with an alkali metal fluoride to form 3-chloro-4,5-difluorobenzonitrile.
    Type: Grant
    Filed: January 27, 1989
    Date of Patent: August 28, 1990
    Assignee: Occidental Chemical Corporation
    Inventors: James J. Maul, David Y. Tang
  • Patent number: 4808760
    Abstract: Telomers are prepared by reacting chlorotrifluoroethylene with 1,2-dibromo-2-chlorotrifluoroethane (CBrClFCF.sub.2 Br) in the presence of a redox catalyst system comprising a metal halide selected from the group consisting of FeCl.sub.3, FeBr.sub.3, CuBr.sub.2, CuCl.sub.2, TiCl.sub.4, VCl.sub.3, and NiCl.sub.2, and a reducing agent selected from the group consisting of Fe, Ni, Cu, Ti, V and benzoin. The preferred catalyst system is ferric chloride and nickel. The telomers of this invention have the structural formula ##STR1## where n is in the range of 1 to 10, and are useful for preparing non-flammable hydraulic fluids.
    Type: Grant
    Filed: January 6, 1986
    Date of Patent: February 28, 1989
    Assignee: Occidental Chemical Corporation
    Inventors: Bobby F. Dannels, Michael J. Fifolt, David Y. Tang
  • Patent number: 4801763
    Abstract: A process is disclosed for purifying and stabilizing a mixture of regular chlorotrifluoroethyelne telomers of formula RCXCl(CF.sub.2 CFCl).sub.n Br from bromine-containing irregular telomer impurities of similar molecular weight. The telomer mixture is produced by reacting chlorotrifluoroethylene with a telogen of formula RCXClBr, where R is CF.sub.2 Br, or Cl, and X is Cl or F. The telomer mixture is then chlorinated using either elevated temperature alone (100.degree. C.-350.degree. C.), or a combination of elevated temperatures (100.degree. C.-200.degree. C.) and light energy primarily of the wavelength region greater than about 3000.degree.A. Under these conditions, CFClBr telomer end group of the regular or normal telomer is chlorinated to form --CFCl.sub.2 end groups, while the bromine-containing irregular telomer impurities (whose bromine-containing end groups are substantially only --CF.sub.2 Br) are substantially not chlorinated.
    Type: Grant
    Filed: July 27, 1987
    Date of Patent: January 31, 1989
    Assignee: Occidental Chemical Corporation
    Inventors: James J. Maul, Bobby F. Dannels, David Y. Tang
  • Patent number: 4792618
    Abstract: Fluoro-substituted carbocyclic compounds are prepared by(A) reacting hydrogen fluoride with a chloro-cyclohexenyl compound of the formula ##STR1## where R.sub.1 and R.sub.2 are independently selected from the group consisting of --H, --CH.sub.2 OH, --COF, --COCl, --CF.sub.3, --CN, ##STR2## and --CH.sub.2 R, where R is --H or alkyl of 1-4 carbon atoms, to form a gem-dihalocyclohexane compound of the formula ##STR3## where X is chlorine and R.sub.1 and R.sub.
    Type: Grant
    Filed: December 12, 1984
    Date of Patent: December 20, 1988
    Assignee: Occidental Chemical Corporation
    Inventors: Joseph F. Bieron, David Y. Tang
  • Patent number: 4704483
    Abstract: A process for the preparation of 3-chloro-4-fluoro-5-nitrobenzotrifluoride and 3,4-difluoro-5-nitrobenzotrifluoride by reaction of 3,4-di-chloro-5-nitrobenzotrifluoride and 4-chloro-3,5-dinitrobenzotrifluoride, respectively, with an alkali metal fluoride.
    Type: Grant
    Filed: December 9, 1985
    Date of Patent: November 3, 1987
    Assignee: Occidental Chemical Corporation
    Inventors: David Y. Tang, Byron R. Cotter, Fredrick J. Goetz
  • Patent number: 4603222
    Abstract: Diphenyl ethers of the formula ##STR1## wherein m is 1-3, n is 1 or 2, R is hydrogen, carboxy, carboxylate salt or ester, formyl oxime, cyano, alkyl, alkoxy, chloro, bromo, or N, N-dialkyl amino, are prepared by reacting a chloro-fluoro-benzotrifluoride of the formula ##STR2## wherein m and n are as defined above with a nitro-phenoxide of the formula ##STR3## where R is defined above, and M is a cation of an alkali metal or an alkaline earth metal.
    Type: Grant
    Filed: August 30, 1984
    Date of Patent: July 29, 1986
    Assignee: Occidental Chemical Corporation
    Inventors: David Y. Tang, Byron R. Cotter, Frederick J. Goetz