Patents by Inventor Hassan Y. Elnagar

Hassan Y. Elnagar 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).

  • Publication number: 20030194514
    Abstract: Propargyl bromide is effectively stabilized against shock or thermal decomposition by use therewith of an environmentally acceptable inert liquid solvent that forms an azeotrope with propargyl bromide.
    Type: Application
    Filed: April 8, 2002
    Publication date: October 16, 2003
    Inventors: Ralph W. Magin, Robert C. Herndon, Mahmood Sabahi, Robert H. Allen, Noel H. Brantley, Hassan Y. Elnagar, Ronny W. Lin
  • Publication number: 20030105350
    Abstract: A process for thermal benzylic bromination of a wide variety of benzylic compounds is described. Bromine is used as the bromination agent. Moderate temperatures are employed and the process can be used to produce in relatively pure form either mono- or dibrominated benzylic bromination products.
    Type: Application
    Filed: December 5, 2001
    Publication date: June 5, 2003
    Inventors: Max K. Mortensen, Hassan Y. Elnagar, Ranjit K. Roy, Robert C. Herndon,, Robert H. Allen, David A. Caillet
  • Patent number: 6508954
    Abstract: Among the enhanced properties of the 1,3-dibromo-5,5-dimethylhydantoins described are their larger average particle sizes, their compactibility even though devoid of a binder, their excellent free-flowing and low-dust properties, and their more appealing aesthetic qualities, as compared to previously known 1,3-dibromo-5,5-dimethylhydantoins. These novel 1,3-dibromo-5,5-dimethylhydantoins can be produced, for example, by concurrently feeding (i) an aqueous solution or slurry formed from an inorganic base and 5,5-dimethylhydantoin, and (ii) a brominating agent, in proportions such that each nitrogen atom is substituted by a bromine atom, thereby forming product which precipitates in an aqueous reaction mixture. The pH of the reaction mixture is maintained in the range of about 5.5 to about 8.5.
    Type: Grant
    Filed: January 18, 2000
    Date of Patent: January 21, 2003
    Assignee: Albemarle Corporation
    Inventors: Hassan Y. Elnagar, Jonathan N. Howarth, Bruce C. Peters, Edgar E. Spielman, Jr., Dustin H. Thomas
  • Patent number: 6489524
    Abstract: Aromatic substrates are Ar-brominated in high yield and selectivity by reacting the substrate with a brominating agent in the presence of at least about 0.19 gram per mmol of substrate of a zeolite catalyst which has an absorbed water content of no greater than about 7.5 weight percent.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: December 3, 2002
    Assignee: Albemarle Corporation
    Inventors: Mahmood Sabahi, Hassan Y. Elnagar, Robert L. Davis
  • Patent number: 6300527
    Abstract: This invention relates, inter alia, to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A and/or underbrominated bisphenol-A, which process features: a water and water-miscible organic solvent reaction medium; a relatively high reaction temperature; and the presence, in the reaction medium, of both (i) excess unreacted Br2 during the feed of bisphenol-A to the reactor, and (ii) sufficient HBr to protect the tetrabromobisphenol-A produced against undesirable color formation. Tetrabromobisphenol-A precipitates from the reaction mass and is easily recovered. Product of high purity (97% or more) and very low color (APHA of 50 or less) can be produced, even when using large excesses of bromine in the reaction.
    Type: Grant
    Filed: July 12, 2000
    Date of Patent: October 9, 2001
    Assignee: Albemarle Corporation
    Inventors: Thanikavelu Manimaran, Hassan Y. Elnagar, Richard A. Holub, Alvin E. Harkins, Jr., Bonnie G. McKinnie
  • Patent number: 6218584
    Abstract: This invention relates, inter alia, to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A and/or underbrominated bisphenol-A, which process features: a water and water-miscible organic solvent reaction medium; a relatively high reaction temperature; and the presence, in the reaction medium, of both (i) excess unreacted Br2 during the feed of bis-phenol-A to the reactor, and (ii) sufficient HBr to protect the tetrabromobisphenol-A produced against undesirable color formation. Tetrabromobisphenol-A precipitates from the reaction mass and is easily recovered. Product of high purity (97% or more) and very low color (APHA of 50 or less) can be produced, even when using large excesses of bromine in the reaction.
    Type: Grant
    Filed: June 10, 1999
    Date of Patent: April 17, 2001
    Assignee: Albemarle Corporation
    Inventors: Thanikavelu Manimaran, Hassan Y. Elnagar, Richard A. Holub, Alvin E. Harkins, Jr., Bonnie G. McKinnie
  • Patent number: 6162953
    Abstract: This invention relates to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A, which process features the addition of bisphenol-A to a reaction mass containing unreacted Br.sub.2 and 30 to 85 wt % water and an alcohol solvent, the reaction mass being at a relatively high temperature.
    Type: Grant
    Filed: September 28, 1999
    Date of Patent: December 19, 2000
    Assignee: Albemarle Corporation
    Inventors: Bonnie G. McKinnie, Richard A. Holub, Hassan Y. Elnagar
  • Patent number: 6121490
    Abstract: A process for producing tertiary amine oxide having two methyl or ethyl groups and one long chain primary aliphatic group in a stable, solid form is described. Aqueous 65-90% hydrogen peroxide and tertiary amine having two methyl or ethyl groups and one primary aliphatic hydrocarbyl group of 8-24 carbon atoms are mixed in proportions of ca. 1.1-1.3 moles of hydrogen peroxide per mole of tertiary amine in the presence of carbon dioxide and in the absence of organic solvent. When the conversion of the tertiary amine to tertiary amine oxide in the reaction mass has reached ca. 60-90%, the reaction mass is transferred to a separate vessel and the reaction mass is then allowed to solidify at a temperature of ca. 20-60.degree. C. The process makes possible the production of highly pure solid product without formation of any appreciable amounts of undesirable by-products.
    Type: Grant
    Filed: April 14, 1999
    Date of Patent: September 19, 2000
    Assignee: Albemarle Corporation
    Inventor: Hassan Y. Elnagar
  • Patent number: 6103926
    Abstract: Direct preparation of benzylically halogenated alkylbenzoic acid ester from an alkylbenzoic acid ester in which the alkyl group is a primary or secondary alkyl group is carried out. The ester group of the starting ester (i) is devoid of non-aromatic unsaturation and (ii) if an aromatic group, is devoid of ring substitution that would undergo benzylic halogenation. The process comprises slowly feeding halogen continuously and/or intermittently to an agitated solution of the alkylbenzoic acid ester in a liquid halogen-containing solvent maintained at a thermal halogenation temperature such that when the alkyl group of the alkylbenzoic acid ester is a primary alkyl group and monohalogenation is desired, the total amount of halogen fed does not exceed about 0.8 mole of halogen per mole of alkylbenzoic acid ester. If the alkylbenzoic acid ester is a toluic acid ester and dihalogenation is desired, the amount of halogen fed is over 1 mole but no more than about 1.8 moles per mole of the toluic acid ester.
    Type: Grant
    Filed: March 12, 1999
    Date of Patent: August 15, 2000
    Assignee: Albemarle Corporation
    Inventor: Hassan Y. Elnagar
  • Patent number: 6084136
    Abstract: This invention relates to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A, which process features: (a) feeding to a reaction mass (i) bisphenol-A and (ii) a stream of gaseous bromine, the gaseous stream having a Reynold's No. .gtoreq.40,000; (b) the reaction mass containing from about 50 to about 20,000 ppm unreacted bromine and less than 20 wt % HBr; and (c) the reaction mass having precipitated therefrom tetrabromobisphenol-A, all of (a)(ii), (b) and (c) occurring during the bisphenol-A feed.
    Type: Grant
    Filed: June 11, 1998
    Date of Patent: July 4, 2000
    Assignee: Albmarle Corporation
    Inventors: Richard A. Holub, Steven R. Alferi, Bonnie G. McKinnie, Hassan Y. Elnagar
  • Patent number: 6084137
    Abstract: This invention relates to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A, which process features the addition of bisphenol-A to a reaction mass containing unreacted Br.sub.2 and 30 to 85 wt. % water and an alcohol solvent, the reaction mass being at a relatively high temperature.
    Type: Grant
    Filed: October 21, 1997
    Date of Patent: July 4, 2000
    Assignee: Albemarle Corporation
    Inventors: Bonnie G. McKinnie, Richard A. Holub, Hassan Y. Elnagar
  • Patent number: 5900512
    Abstract: An oxidation process for organic compounds employs stabilized bromine chloride solutions as the oxidizing agent. Organic compounds which contain an oxidizable moiety, such as thioanisole and triphenylphosphine, are rapidly converted to sulfoxides and phosphine oxides, respectively, without over-oxidation.
    Type: Grant
    Filed: September 11, 1997
    Date of Patent: May 4, 1999
    Assignee: Albemarle Corporation
    Inventors: Hassan Y. Elnagar, Robert L. Davis
  • Patent number: 5861522
    Abstract: Bridged metallocene compounds are produced by a process of promising commercial utility for plant-sized operations. One of the key steps of the process involves converting a deprotonated silicon-, germanium- or tin-containing ligand into the metallocene. Preferably, and in accordance with an embodiment of the invention, this is accomplished to great advantage by adding a diamine adduct of a Group IV, V, or VI metal tetrahalide to a solution or slurry formed from a deprotonated silicon-, germanium- or tin-containing ligand and an organic liquid medium so as to form a metallocene. The overall process of the invention involves the direct conversion of benzoindanones to benzoindanols which, without isolation, are converted to benzoindenes. Thereupon the benzoindenes are bridged by deprotonating the benzoindenes with a strong base such as butyllithium and reacting the resultant deprotonated product with a suitable silicon-, germanium- or tin-containing bridging reactant such as dichlorodimethylsilane.
    Type: Grant
    Filed: May 8, 1997
    Date of Patent: January 19, 1999
    Assignee: Albemarle Corporation
    Inventors: Meng-Sheng Ao, Hassan Y. Elnagar, Arcelio J. Malcolm, Jamie R. Strickler, Ronny W. Lin, John F. Balhoff
  • Patent number: 5817888
    Abstract: A bromination process for organic compounds employs stabilized bromine chloride solutions as the brominating agent. Activated aromatic compounds such as anisole can be selectively monobrominated in the para-position in high purity and yield.
    Type: Grant
    Filed: June 9, 1997
    Date of Patent: October 6, 1998
    Assignee: Albemarle Corporation
    Inventors: Hassan Y. Elnagar, Robert L. Davis, Mahmood Sabahi
  • Patent number: 5710299
    Abstract: Bridged metallocene compounds are produced by a process of promising commercial utility for plant-sized operations. The overall process involves the direct conversion of benzoindanones to benzoindanols which, without isolation, are converted to benzoindenes. Thereupon the benzoindenes are bridged by deprotonating the benzoindenes with a strong base such as butyllithium and reacting the resultant deprotonated product with a suitable silicon-, germanium- or tin-containing bridging reactant such as dichlorodimethylsilane. The resultant bridged product is deprotonated with a strong base such as butyllithium and reacted with a suitable Group IV, V, or VI metal-containing reactant such as ZrCl.sub.4 to provide a silicon-, germanium- or tin-bridged Group IV, V, or VI metal complex, such as a dihydrocarbylsilyl-bridged zirconocene complex.
    Type: Grant
    Filed: June 27, 1996
    Date of Patent: January 20, 1998
    Assignee: Albemarle Corporation
    Inventors: Meng-Sheng Ao, Hassan Y. Elnagar, Arcelio J. Malcolm, Jamie R. Strickler
  • Patent number: 5654486
    Abstract: Partially sterically-hindered cycloalkyl chlorides are reacted with lithium diarylphosphides in inert liquid hydrocarbon reaction media to form cycloalkyldiarylphosphines. Aryl lithium is coproduced. The process makes it possible to avoid, or at least substantially eliminate, the interaction with or cleavage of cyclic ether reaction media such as tetrahydrofuran, previously the solvent of choice for conducting this type of reaction. Also during the conduct of the present process the chloro-substituted cycloalkane does not undergo any appreciable reaction with the coproduced aryl lithium as it is formed. Thus improvements both in yield and quality of the cycloalkyldiarylphosphine product are made possible. A comprehensive three-step process for converting triarylphosphine to cycloalkyldiarylphosphine is also described.
    Type: Grant
    Filed: March 25, 1996
    Date of Patent: August 5, 1997
    Assignee: Albemarle Corporation
    Inventors: K. Pushpananda A. Senaratne, Arcelio J. Malcolm, Felix M. Orihuela, Hassan Y. Elnagar
  • Patent number: 5654485
    Abstract: By reacting certain partially sterically-hindered chloro-substituted cycloalkanes with sodium and/or potassium diarylphosphides in an ether reaction medium, not only are useful cycloalkyldiarylphosphines produced, but in addition the chloro-substituted cycloalkane does not undergo any appreciable reaction with the coproduced aryl sodium and/or aryl potassium as it is formed. Moreover, the process makes it possible to avoid or at least to greatly reduce interaction with or cleavage of cyclic ether reaction media such as tetrahydrofuran. Thus the process makes possible improvements both in yield and quality of the cycloalkyldiarylphosphite product. A two-stage process conducted in an ether reaction medium is also described. In the first stage the sodium and/or potassium diarylphosphine reactant is produced by reaction between sodium and/or potassium and triarylphosphine.
    Type: Grant
    Filed: March 25, 1996
    Date of Patent: August 5, 1997
    Assignee: Albemarle Corporation
    Inventors: K. Pushpananda A. Senaratne, Arcelio J. Malcolm, Felix M. Orihuela, Hassan Y. Elnagar
  • Patent number: 5565600
    Abstract: Novel alkyl-aromatic diphosphites having antioxidant and flame-retarding abilities and corresponding to the formula: ##STR1## can be prepared by reacting a 2,2'-bridged bisphenol corresponding to the formula: ##STR2## with pentaerythritol dichlorophosphite at 20-150.degree. C. in the presence of a basic catalyst; R and R' in the formulas representing hydrocarbyl groups, R" being a divalent bridging group, and n being 0 or 1. These diphosphites have good hydrolytic stability per se and can be made even more resistant to hydrolysis by stabilizing them with at least 0.5% by weight of an acid scavenger, preferably before they are recovered from their synthesis reaction mixtures.
    Type: Grant
    Filed: June 26, 1995
    Date of Patent: October 15, 1996
    Assignee: Albemarle Corporation
    Inventor: Hassan Y. Elnagar
  • Patent number: 5103035
    Abstract: Bis(alkylphenyl)pentaerythritol diphosphite is produced by forming a reaction mass from phosphorous trichloride, pentaerythritol, a chlorinated hydrocarbon solvent and a heterocyclic tertiary amine catalyst followed by the addition of an alkylphenol to the reaction mass. The process further features the use of mild conditions.
    Type: Grant
    Filed: April 5, 1990
    Date of Patent: April 7, 1992
    Assignee: Ethyl Corporation
    Inventors: Hassan Y. Elnagar, Kestutis A. Keblys