- Preparation method of p-hydroxyphenylhydantoin
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The invention provides a preparation method of p-hydroxyphenylhydantoin. The p-hydroxyphenylhydantoin is obtained by a condensing cyclization reaction of glyoxylic acid, phenol and urea, which are used as raw materials, under the catalysis of a solid acid, and the solid acid is at least one of an acidic ion exchange resin, a heteropoly acid, a metal salt, a carrier-supported metal salt compound and a metal oxide. The preparation method which adopts the solid acid as a catalyst has the characteristics of simple process, high product selectivity, few byproducts, high yield, good purity, and easiness in product separation, and is suitable for large-scale industrial production.
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Paragraph 0023-0080
(2019/10/23)
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- Preparation method of 5-p-hydroxyphenyl hydantoin
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The invention provides a preparation method of 5-p-hydroxyphenyl hydantoin. The 5-p-hydroxyphenyl hydantoin is synthesized by means of a one-step method by taking glyoxylic acid, phenol and urea as raw materials and using modified styrene divinylbenzene as a catalyst, wherein the reaction temperature is 340-345K, the reaction time is 20-24h, and the reaction molar ratio of the glyoxylic acid to the phenol to the urea to the modified styrene divinylbenzene is equal to 1: (1-1.5): (1.5-2): (2.2-3); the modified styrene divinylbenzene is obtained by modifying styrene divinylbenzene by taking 98% of H2SO4 as a modifying agent. The preparation method of the 5-p-hydroxyphenyl hydantoin is simple in production technology, low in price of raw materials, easy in raw material obtaining and high in product yield; furthermore, less waste liquid is produced in the production process, and the catalyst can be recycled.
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Paragraph 0029; 0030; 0032; 0033; 0035; 0036
(2017/08/29)
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- Production method for para hydroxybenzene
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The invention provides a production method for para hydroxybenzene and belongs to the field of chemical engineering and pharmaceutical production. Glyoxylic acid is added dropwise to urea, phenol and a hydrochloric acid system to synthesize crude para hydroxybenzene, and fine para hydroxybenzene is prepared through a refining procedure. According to the production method for para hydroxybenzene, a proper raw material ratio, proper reaction temperature and other synthesis conditions are selected, the refining procedure is added, therefore, the yield of para hydroxybenzene can be effectively increased, and the yield of para hydroxybenzene can reach 70% or above; the technological process is simple, easy to carry out and free of pollution.
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Paragraph 0032-0042
(2017/06/23)
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- P-hydroxy-glycine preparation method (by machine translation)
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The invention provides a method for the preparation of hydroxy-phenyl glycine, comprising the following steps: A synthetic hydroxy because benzene sea, B. Hydroxyphenyl hydantoin as a result of the hydrolysis, the present invention provides a preparation method, high efficiency, high output, suitable for large-scale mass production. (by machine translation)
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Paragraph 0022-0025
(2017/06/29)
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- The use of Lewis acids in the synthesis of 5-arylhydantoins
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Different Lewis acids are able to promote the Friedel-Crafts reaction between 5-bromohydantoin and aromatic compounds. In the case of phenol, mixtures of ortho and para isomers are always obtained, with Mg(ClO4) 2 leading to the best selectivity. However, the best overall yield of 5-(hydroxyphenyl)hydantoin is obtained with YbCl3. This method can be extended to other aromatic systems such as anisole and thiophene. These reactions give similar yields but proceed with total selectivity to 5-(4-methoxyphenyl)hydantoin and 5-(2-thiophenyl)hydantoin, respectively. The cationic exchange of MgII and YbIII on anionic solid supports allows the preparation of very efficient heterogeneous catalysts for this reaction (productivity up to 600 mol of hydantoin per mole of Mg). These catalysts have practical advantages in that they can be recycled and reused.
- Cativiela, Carlos,Fraile, Jose M.,Garcia, Jose I.,Lafuente, Gustavo,Mayoral, Jose A.,Tahir, Rachid,Pallares, Antonio
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p. 192 - 196
(2007/10/03)
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- Ultrasound-promoted synthesis of 5-substituted and 5,5-disubsntuted hydantoins
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Sonication of a mixture of industrial grade sodium cyanide (aqueous solution) and ammonium carbonate in aqueous alcohol with aldehydes or ketones affords the 5-substituted or 5,5-disubstituted hydantoins in 30-92percent yield.
- Li, Jital,Li, Lijun,Li, Tongshuang,Waog, Jianzhong
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p. 298 - 300
(2007/10/03)
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- Process for preparing 5-arylhydantoins using 5-hydantoin, a halogenating agent and p-phenol
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The present invention provides a novel process for the preparation of 5-arylhydantoins as an important intermediate of (D)-arylglycines (e.g., (D)-p-hydroxyphenyl-glycine) useful for the synthesis of semisynthetic penicillines and cephalosporins, the process comprising (i) reacting a 5-unsubstituted hydantoin compound with a halogenating agent and (ii) reacting the resulting product with a p-unsubstituted phenol compound, the hydroxy group of which may be protected, to substitute the 5-position of the hydantoin compound with the phenol compound at the para position.
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- Production of ring-substituted D-phenylglycines by microbial or enzymatic hydrolysis/deracemisation of the corresponding DL-hydantoins
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A series of 17 ring-mono and -disubstituted D-phenylglycine derivatives was prepared in high enantiomeric purity by enzymatic hydrolysis and deracemisation of the corresponding DL-hydantoins, using D-hydantoinase activities of microorganisms or purified enzymes, followed by diazotation of the resulting N-carbamyl-D-amino acids. No significant L-hydantoinase activity was found to produce the corresponding L-enantiomers.
- Garcia, Maria J.,Azerad, Robert
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- Process for the preparation of arylhydantoins
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Process for the preparation of 5-arylhydantoins by reaction of an allantoin acid alkyl ester with an aryl compound in a concentrated inorganic acid at temperatures from room temperature to 150° C., with or without a phase transfer agent.
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- Process for preparing 5-hydroxyhydantoin
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A process for preparing 5-hydroxyhydantoin which comprises oxidizing 4,5-dihydroxyimidazolin-2-one having formula (I): STR1 with hydrogen peroxide in an aqueous medium in the presence of a metal ion. According to the process, 5-hydroxyhydantoin is readily prepared from inexpensive starting materials.
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- Formation of hydroxyaromatic ketoacetal from a hydroxyaromatic methylketone and production of 5-(4'-hydroxyphenyl)hydantoin and Dp-hydroxyphenylglycine from 4-hydroxyacetophenone
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The present invention provides a method for producing a hydroxyaromatic ketoacetal from a hydroxyaromatic methylketone. The invention further provides a method for producing a hydroxyaromatic ketoaldehyde from a hydroxyaromatic ketoacetal. The hydroxyaromatic ketoaldehyde can be further reacted to form a hydantoin, which hydantoin can be hydrolyzed to produce a hydroxyphenylglycine.
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- Process for preparing 5-(4-hydroxyphenyl)hydantoin
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A process for preparing 5-(4-hydroxyphenyl)hydantoin by reacting glyoxylic acid, urea and phenol in an aqueous medium in the presence of an acid at an elevated temperature. The hydantoin of high purity can be readily prepared in good yields.
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