Patents by Inventor Hans Kratzer

Hans Kratzer 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: 4898974
    Abstract: Dichloropinacolone is produced by introducing into pinacolone twice the molar amount of chlorine, the exothermic reaction mass being cooled initially to maintain the temperature below about 50.degree. C. until about 60 to 80% of the chlorine has been introduced, and then heating the reaction mass to a temperature above 50.degree. C. during introducing of the remainder of the chlorine, thereby to produce dichloropinacolone, and terminating chlorine introduction when the dichloropinacolone content of the reaction mass is at least about 97%. The molten product is added to an aqueous solution of an alkali maintained at a temperature of at least about 50.degree. C., the alkali being present in more than three times the molar amount of the dichloropinacolone. To the resulting solution of a salt of 3,3-dimethyl-2-hydroxy-butyric acid, brought to a pH of about 9 to 12, there is added approximately the stoichiometric amount of potassium permanganate. Solid MnO.sub.
    Type: Grant
    Filed: April 23, 1985
    Date of Patent: February 6, 1990
    Assignee: Bayer Aktiengesellschaft
    Inventors: Karlfried Dickore, Hans D. Engels, Hans Kratzer, Walter Merz
  • Patent number: 4564704
    Abstract: Dichloropinacolone is produced by introducing into pinacolone twice the molar amount of chlorine, the exothermic reaction mass being cooled initially to maintain the temperature below about 50.degree. C. until about 60 to 80% of the chlorine has been introduced, and then heating the reaction mass to a temperature above 50.degree. C. during introducing of the remainder of the chlorine, thereby to produce dichloropinacolone, and terminating chlorine introduction when the dichloropinacolone content of the reaction mass is at least about 97%. The molten product is added to an aqueous solution of an alkali maintained at a temperature of at least about 50.degree. C., the alkali being present in more than three times the molar amount of the dichloropinacolone. To the resulting solution of a salt of 3,3-dimethyl-2-hydroxy-butyric acid, brought to a pH of about 9 to 12, there is added approximately the stoichiometric amount of potassium permanganate. Solid MnO.sub.
    Type: Grant
    Filed: January 22, 1981
    Date of Patent: January 14, 1986
    Assignee: Bayer Aktiengesellschaft
    Inventors: Karlfried Dickore, Hans D. Engels, Hans Kratzer, Walter Merz
  • Patent number: 4360479
    Abstract: This invention relates to a new process for the preparation of acyl cyanides of the general formulaR.sup.1 --CO--CN (I)wherein R.sup.1 is an optionally substituted alkyl radical up to 18 carbon atoms, an optionally substituted cycloalkyl radical with 3 to 12 carbon atoms, an optionally substituted aryl radical or an optionally substituted 5- or 6-membered heterocyclic radical, which can additionally also be fused with a benzene ring, which process comprises reacting a carboxylic acid anhydride of the formulaR.sup.1 --CO--O--CO--R.sup.1 (II)with an alpha-hydroxynitrile of the formula ##STR1## in which R.sup.2 and R.sup.3 are identical or different and represent a hydrogen atom, an optionally substituted alkyl radical with 1 to 18 carbon atoms, an optionally substituted cycloalkyl radical with 3 to 12 carbon atoms, an optionally substituted aryl radical or an optionally substituted 5- or 6-membered heterocyclic radical, which can additionally also be fused with a benzene ring.
    Type: Grant
    Filed: June 24, 1981
    Date of Patent: November 23, 1982
    Assignee: Bayer Aktiengesellschaft
    Inventors: Kurt Findeisen, Hans Kratzer, Manfred Lenthe
  • Patent number: 4328340
    Abstract: In the preparation of 4-amino-6-tert.-butyl-3-methylthio-1,2,4-triazin-5-(4H)-one of the formula ##STR1## wherein pivaloyl cyanide of the formula(CH.sub.3).sub.3 C--CO--CNis reacted to form an intermediate, the intermediate is condensed with thiocarbohydrazide of the formulaNH.sub.2 --NH--CS--NH--NH.sub.2to form 4-amino-6-tert.-butyl-3-mercapto-1,2,4-triazin-5-(4H)-one of the formula ##STR2## and the 4-amino-6-tert.-butyl-3-mercapto-1,2,4-triazin-5-(4H)-one is alkylated to replace the H atom on the sulphur by --C.sub.1-4 --alkyl, the improvement which comprises reacting the pivaloyl cyanide with a carboxylic acid anhydride of the formulaR--CO--O--CO--Rin which R is an optionally substituted aliphatic radical with up to 8 carbon atoms or an optionally substituted phenyl radical, in the presence of a strong acid at a temperature between about -50.degree. and +150.degree. C., and then directly reacting the reaction mixture thus obtained with the thiocarbahydrazide. Advantageously R is CH.sub.
    Type: Grant
    Filed: February 19, 1981
    Date of Patent: May 4, 1982
    Assignee: Bayer Aktiengesellschaft
    Inventors: Gerhard Bonse, Heinz U. Blank, Hans Kratzer
  • Patent number: 4315094
    Abstract: In the preparation of 4-amino-6-tert.-butyl-3-alkylthio-1,2,4-triazin-5-(4H)-one of the formula ##STR1## wherein (1) pivaloyl cyanide of the formula(CH.sub.3).sub.3 C--CO--CNis reacted to form a derivative of pyruvic acid, (2) the pyruvic acid derivative is condensed with thiocarbohydrazide of the formulaNH.sub.2 --NH--CS--NH--NH.sub.2to form 4-amino-6-tert.-butyl-3-mercapto-1,2,4-triazin-5(4H)-one of the formula ##STR2## and (3) this is alkylated, the improvement which comprises effecting step (1) by reaction with a carboxylic acid anhydride of the formulaR--CO--O--CO--Rin which R is an optionally substituted aliphatic radical with up to 8 carbon atoms or an optionally substituted phenyl radical, in the presence of a strong acid at a temperature between about -50.degree. and +150.degree. C., and then adding water to the reaction mixture, thereby to form trimethylpyruvic acid N-acylamide of the formula(CH.sub.3).sub.3 C--CO--CO--NH--CO--R.
    Type: Grant
    Filed: February 19, 1981
    Date of Patent: February 9, 1982
    Assignee: Bayer Aktiengesellschaft
    Inventors: Gerhard Bonse, Heinz U. Blank, Hans Kratzer
  • Patent number: 4309538
    Abstract: In the preparation of 4-amino-6-tert.-butyl-3-alkylthio-1,2,4-triazin-5(4H)-ones of the formula ##STR1## wherein (a) pivaloyl cyanide of the formula(CH.sub.3).sub.3 C--CO--CNis converted to a derivative of trimethylpyruvic acid, (b) the derivative is condensed with thiocarbohydrazide of the formulaH.sub.2 N--NH--CS--NH--NH.sub.2to form 4-amino-6-tert.-butyl-3-mercapto-1,2,4-triazin-5(4H)-one, and (c) that is alkylated to form the indicated end products, the improvement which comprises effecting (a) by reacting the pivaloyl cyanide with a strong anhydrous inorganic acid at about -50.degree. to +50.degree. C. thereby to form trimethylpyruvic acid amide. The derivative in (a) can be trimethylpyruvic acid amide or it may first be saponified to the free acid. The inorganic acid in (a) can be hydrochloric or hydrobromic acid in glacial acetic acid, or it can be concentrated sulphuric acid plus some chloride ion and followed by water. Trimethyl pyruvic acid amide is a new compound.
    Type: Grant
    Filed: January 22, 1981
    Date of Patent: January 5, 1982
    Assignee: Bayer Aktiengesellschaft
    Inventors: Thomas Schmidt, Andreas Wittig, Hans-Peter Sehnem, Hans Kratzer, Rolf-Jurgen Singer
  • Patent number: 4052460
    Abstract: Dichloropinacolone is produced by introducing into pinacolone twice the molar amount of chlorine, the exothermic reaction mass being cooled initially to maintain the temperature below about 50.degree. C until about 60 to 80% of the chlorine has been introduced, and then heating the reaction mass to a temperature above 50.degree. C during introducing of the remainder of the chlorine, thereby to produce dichloropinacolone, and terminating chlorine introduction when the dichloropinacolone content of the reaction mass is at least about 97%. The molten product is added to an aqueous solution of an alkali maintained at a temperature of at least about 50.degree. C, the alkali being present in more than three times the molar amount of the dichloropinacolone. To the resulting solution of a salt of 3,3-dimethyl-2-hydroxy-butyric acid, brought to a pH of about 9 to 12, there is added approximately the stoichiometric amount of potassium permanganate. Solid MnO.sub.
    Type: Grant
    Filed: January 20, 1976
    Date of Patent: October 4, 1977
    Assignee: Bayer Aktiengesellschaft
    Inventors: Karlfried Dickore, Hans Dieter Engels, Hans Kratzer, Walter Merz