Patents by Inventor Alfred Maierhofer

Alfred Maierhofer 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).

  • Process for the purification of tryptophane and derivatives of tryptophane
    Patent number: 4283337
    Abstract: Tryptophane and tryptophane derivatives are purified by treating them in an inert solvent at a temperature between about 20.degree. C. and the boiling point of the mixture with a salt of dithionous acid. Preferably there is used as solvent a mixture of water and a lower aliphatic carboxylic acid. Normally a single treatment results in a pure, colorless, satisfactory product.
    Type: Grant
    Filed: November 15, 1979
    Date of Patent: August 11, 1981
    Assignee: Deutsche Gold und- Silber-Scheideanstalt Vormals Roessler
    Inventors: Theodor Lussling, Alfred Maierhofer, Paul Scherberich
  • Process for the production of benzoyl cyanide (I)
    Patent number: 4209461
    Abstract: The process described in Klenk U.S. Pat. No. 4,113,773 is improved by employing alkali metal cyanide in which at least half of the alkali metal cyanide has a particle size below 0.4 mm and the remainder has a particle size below 1.0 mm.
    Type: Grant
    Filed: December 1, 1978
    Date of Patent: June 24, 1980
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Herbert Klenk, Theodor Lussling, Alfred Maierhofer, Heribert Offermanns, Hans Wagner
  • Process for the production of benzoyl cyanide (IV)
    Patent number: 4144269
    Abstract: Benzoyl cyanide is made from benzoyl chloride and an alkali metal cyanide in a two phase system comprising water and an inert organic solvent which has only slight miscibility with water in the presence of a tertiary amine and hydrogen cyanide.
    Type: Grant
    Filed: June 2, 1977
    Date of Patent: March 13, 1979
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Herbert Klenk, Theodor Lussling, Alfred Maierhofer, Heribert Offermanns, Hans Wagner
  • Process for the production of high purity S-carboxymethyl-L-cysteine
    Patent number: 4129593
    Abstract: Very pure S-carboxymethyl-L-cysteine is prepared by reacting L-cystine in liquid ammonia with metallic sodium to form the disodium salt of L-cysteine, evaporating the ammonia, reacting the disodium salt of L-cysteine with an aqueous solution of chloroacetic acid and precipitating the S-carboxymethyl-L-cysteine formed by acidifying the reaction mixture. There is employed 0.1 to 10 weight percent of a reducing agent based on the chloroacetic acid.
    Type: Grant
    Filed: September 14, 1977
    Date of Patent: December 12, 1978
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Alfred Maierhofer, Hans Wagner
  • Sweet material
    Patent number: 4119738
    Abstract: 2-Hydroxy-4-methyl valeric acid and its salts are useful as sweeteners. The preferred sweeteners are the sodium and potassium salts.
    Type: Grant
    Filed: May 17, 1976
    Date of Patent: October 10, 1978
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Hans Wagner, Alfred Maierhofer
  • Process for the production of benzoyl cyanide (I)
    Patent number: 4113773
    Abstract: Benzoyl cyanide is made by reacting benzoyl chloride with an alkali cyanide in the presence of a carboxylic acid nitrile and a copper (I) salt at a temperature of about 50.degree. to 160.degree. C.
    Type: Grant
    Filed: June 20, 1977
    Date of Patent: September 12, 1978
    Assignee: Deutsche Gold- und Silber-Scheideanstalt Vormals Roessler
    Inventors: Herbert Klenk, Theodor Lussling, Alfred Maierhofer, Heribert Offermanns, Hans Wagner
  • Process for the production of N-acetyl-L-methionine
    Patent number: 4011263
    Abstract: N-acetyl-L-methionine is prepared by reacting L-methionine with acetic anhydride in the presence of aqueous alkali at a temperature between 20.degree. and 60.degree. C. at a pH between 6.5 and 10. Preferably, there are used 1.05 to 1.70 moles of acetic anhydride per mole of L-methionine.
    Type: Grant
    Filed: May 11, 1976
    Date of Patent: March 8, 1977
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Hans Wagner, Alfred Maierhofer
  • Process for the production of 3,6-bis-(2-methylmercaptoethyl)-2,5-piperazinedione
    Patent number: 3980653
    Abstract: 3,6-BIS-(2-METHYLMERCAPTOETHYL)-2,5-PIPERAZINEDIONE IS PREPARED FROM 5-(2-METHYLMERCAPTOETHYL)-HYDANTOIN IN THE PRESENCE OF WATER AT 100.degree. TO 200.degree.C. at elevated pressure.
    Type: Grant
    Filed: June 26, 1975
    Date of Patent: September 14, 1976
    Assignee: Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
    Inventors: Hans Wagner, Alfred Maierhofer