- Cleavage of Carboxylic Esters by Aluminum and Iodine
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A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
- Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
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p. 4254 - 4261
(2021/03/09)
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- Synthetic method for ultraviolet absorbent namely 4,4'-dihexyloxybenzophenone
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The invention discloses a synthetic method for an ultraviolet absorbent namely 4,4'-dihexyloxybenzophenone. The method comprises the following steps: with p-hydroxybenzoic acid as a starting material, carrying out acetylation to protect hydroxy; carrying out a Fredel-Crafts reaction of p-acetoxybenzoic acid and phenol under the catalysis of zinc chloride and phosphorus oxychloride so as to synthesize an intermediate namely phenyl p-hydroxybenzoate; then carrying out deacetylation to remove the protective group, and carrying out Fries rearrangement so as to prepare an intermediate namely 4,4-dihydroxybenzophenone; and forming a salt with 4,4-dihydroxybenzophenone and potassium carbonate, and carrying out a Williamson reaction of 1-bromohexane and the potassium salt of 4,4-dihydroxybenzophenone through catalysis of tetrabutylammonium bromide so as to synthesize the 4,4'-dihexyloxybenzophenone. The synthetic method provided by the invention has the advantages of mild reaction conditions, normal pressure, medium and low temperature, stable quality control, high raw material conversion rate, effective inhibition of side reactions, fewer three wastes, light pollution, and facilitation of protecting the environment and labor of a producer.
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Paragraph 0020; 0025; 0030; 0035; 0040
(2017/09/13)
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- Regiospecific phenyl esterification to some organic acids catalyzed by combined Lewis acids
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A new and efficient method for the preparation of various phenyl esters has been achieved by a simple reaction of an acid with phenol in the presence of anhyd. ZnCl2 and a catalytic amount of AlCl3. This combined Lewis acid also catalyzes the selective phenyl esterification to different dioic acids and is very simple and high yielding. Copyright Taylor & Francis Group, LLC.
- Roy,Mamun, A. H. Al
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p. 2975 - 2981
(2007/10/03)
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- The chemoselective preparation of the substituted phenyl benzoates using re-Y zeolite as catalyst
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A practical and chemoselective method for the synthesis of substituted phenyl benzoates using rare earth zeolite as catalyst was described, its recycle procedure offers high total yield.
- Ding, Yixiang,Wu, Rui,Lin, Qiang
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p. 2149 - 2153
(2007/10/03)
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- Formation of Dichloromethyl Phenyl Ethers as Major Products in Photo-Reimer-Tiemann Reaction without Base
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Photolysis of phenols 1a-d in chloroform or carbon tetrachloride afforded the corresponding di- or trichloromethyl phenyl ethers (2a-d or 6a-d, respectively).In chloroform, hydroxybenzaldehydes 4a-d or 5 and phenyl formates 3a-d were obtained as minor photoproducts.In carbon tetrachloride, traces of salicyloyl chloride (7), phenyl salicylate (8) and phenyl p-hydroxybenzoate (9) were detected starting from the parent phenol (1a).The obtained results agree with the involvement of an electron transfer mechanism.
- Jimenez, M. Consuelo,Miranda, Miguel A.,Tormos, Rosa
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p. 5825 - 5830
(2007/10/02)
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- N-METHYL-2-DIMETHYLAMINOACETOHYDROXAMIC ACID AS A NEW REAGENT FOR THE SELECTICE CLEVEAGE OF ACTIVE ESTERS UNDER NEUTRAL CONDITIONS
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A new reagent, N-methyl-2-dimethylaminoacetohydroxamic acid 3 was developed for the selective cleavage of active esters under neutral conditions.The kinetic studies and the applications of 3 are described.
- Ono, Mitsunori,Itoh, Isamu
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p. 207 - 210
(2007/10/02)
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- SYNTHESIS OF HYDROXYETHYL P-β-HYDROXYETHYLBENZOATE
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Hydroxyethyl p-β-hydroxyethylbenzoate was synthesized by the reaction of p-hydroxybenzoic acid or its esters with ethylene glycol in the presence of substituted orthotitanate esters. p-Hydroxybenzoic acid reacts with greater difficulty than its lower alkyl or aryl esters.
- Ignateva, E. K.,Kulishina, V. I.
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p. 1544 - 1545
(2007/10/02)
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- Oxybenzoyl dioxyarylene mono- and diesters
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Branched, wholly aromatic polyesters of Formula I EQU1 wherein R1, R2 and R3 each consist essentially of a plurality of moieties selected from the group having the Formulas II, III and IV SPC1 and wherein X is -O-, EQU2 m is 0 or 1; n is 0 or 1; a is 0-40; b is 0-20; c is 0-20; and a + b + c is 2- 40.
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