Salicylic ester

The manipulation of calcium hydroxide paste is not easy, however, and Dougherty (1962) introduced the calcium hydroxide salicylate cements. These are based on the reaction between calcium hydroxide and salicylate esters and come in two-paste packs which are easy to mix in the dental surgery. 

Salicylate esters may be promising prodrug candidates for estrogen. 0-Estradiol has been used for treatment of various conditions such as menopausal... 

It is primarily the prospect of reduced mobility and volatility, with the expected improvement in long-term performance, which motivates the preparation of polymeric ultraviolet stabilizers. Work in this area was reviewed thoroughly by Bailey and Vogl in 1976 (1), and more recently by the author (2). The present paper describes recent synthetic work involving four classes of effective ultraviolet stabilizers salicylate esters (I), 2-hydroxybenzophenones (II), a-cyano-3-phenyl-cinnamates (III) and hydroxyphenylbenzotriazoles (IV). In each... 

Radical polymerizations of vinyl-substituted ultraviolet stabilizers were accomplished with azobisisobutyronitrile (AIBN) as initiator, with careful exclusion of oxygen. Copolymerization was also readily achieved. The following sections describe in detail the preparation of polymeric ultraviolet stabilizers from salicylate esters, 2-hydroxybenzophenones, a-cyano-p-phenyl-cinnamates and hydroxyphenylbenzotriazoles. 

Salicylate Esters. The methyl esters of three isomeric vinylsalicylic acids (the 3-, 4- and 5-vinyl compounds) have been prepared, using the synthetic routes outlined above. 

Each of the derivatives may be regarded as a substituted styrene, and classical styrene syntheses have been employed. Radical polymerization of the phenolic monomers (salicylate esters, 2-hydroxybenzophenones and hydroxyphenylbenzotriazoles) proceeds normally with AIBN as initiator, at least when oxygen is carefully excluded. It is expected that polymeric ultraviolet stabilizers, perhaps in combination with conventional stabilizer will make an important contribution to photostabilization technology. 

Examples of reactions involving replacement and cyclization are the long-known preparation of thiophenes (89) from 1,4-diketones, and the formation of l,2-dithiole-3-thione (90) from the salicylate ester analog (91).120 In the latter instance, oxidative cyclization with formation of an S—S bond has occurred this is a common feature of these reactions, particularly if such a link is needed to complete a five-membered ring. Another example of this aspect is afforded by the reaction of the propane-1,3-dione derivatives (92) which yield 3,5-diaryl-1,2-dithiolylium salts (93) when heated with phosphorus pentasulfide in carbon disulfide, followed by perchloric acid.121... 

The resin-bound salicylic esters were suspended in N,N-dimethylformamide (DMF) and placed in an Erlenmeyer flask within a domestic microwave cavity. After microwave irradiation for 4—6 min (1 min cycles), the reaction mixture was allowed to cool to ambient temperature and the resin was collected by fdtration and washed with methanol and dichloromethane. The desired compounds were subsequently cleaved with trifluoroacetic acid in dichloromethane. Removal of the solvent by evap-... 

The Ni - and Zn " " -complexes of phenyl and salicyl esters of pyridine-2,6-dicarboxylic acid [50a and b] hydrolyse much faster than the uncomplexed esters (Breslow and McAllister, 1971) the rate of hydroxide ion catalysis of the Ni " -complexes increases 9300... 

The main commercial applications for salicylate esters are as uv sunscreen agents and as flavor and fragrance agents. Several have application as topical analgesics. A number of salicylate esters of commercial interest and their physical properties are listed in Table 8. 

A subcategory of dopamine receptor antagonists has found some use as antiemetic agents administered in conjunction with antimmor chemotherapy. The preparation of one of these agents based on a benzotriazole nucleus begins with nitration of the amino salicylate ester (67-1). Catalytic hydrogenation of the product (67-2) leads to the orf/zo-diamine (67-3). Treatment of this last product with nitrous acid... 

With both substrates, cleavage of salicyl esters is markedly accelerated in the presence of polyethylenimines. The first-order rate constant k2 in... 

Fused oxygen and nitrogen-containing rings may also be prepared in reactions with thioureas thus, dihydrobenzoxazine products are obtained on treatment of salicyloyl chloride with thioureas371 or on fusion of salicylate esters with thiopseudoureas.320 When the thio-pseudoureas are treated with o-aminophenol, the products are benzoxa-zoles.320 A naphthyl analog of a benzoxazole is produced on treatment of l-(2-hydroxy-l-naphthyl)-2-thiourea with dimethyl sulfate.372... 

Salicylic acid derivatives, such as aspirin (acetyl-salicylic acid), have long been known as pain relievers for the human body. The major effect is thought to be inhibition of a cyclooxygenase (Eq. 21-16). Willow bark has been known since the 18th century to contain a pain reliever, which was identified as salicylate esters and salicyl alcohol derivatives such as salicin. 

The production and isolation of the antibiotic celesticetin (2), a salicylate ester of the fi-hydroxyethyltliio-substituent, was repotted as early as die 1950s, although its structure was not determined until 1968. 

Phenylis Salicylas, Phenyl Salicylate, Salol, C13H10O3, is the salicylic ester of phenyl, and occurs as a white, crystalline powder, odorless and almost tasteless, nearly insoluble in water, soluble in 10 parts alcohol, and very soluble in ether, chloroform, and oils. On warming with an alkali, it splits up into salicylic acid 60, and phenol 40, frequently repeated, in compressed tablets or in cachets, or suspended by mucilage of acacia or of tragacanth. 

Until now, only few attempts were made to control the absolute configuration of the chiral polycyclic products. When salicylic esters of type 77 (Sch. 14) possessing an asymmetric alcohol moiety as chiral auxiliary instead of the n-butyl group are irradiated, the corresponding products can be isolated with 17% ee [50]. Better results can be obtained with the additionally acylated substrates 79a-c (Sch. 15). Compounds 80a-c were isolated with diastereomeric excesses up to 90% [29,56]. These compounds were formed via [2+2] photocycloaddition yielding the intermediates X. A thermal rearrangement leads to 80a-c. Compounds 81a-c are produced in the same time via a further photochemical rearrangement but due to thermal reversibility of the last step, 80a-d could be isolated with yields up to 90% when the reaction was completed. 

Salicyl esters acetate (C2) propionate (C3) butyrate (C4) caproate (Ce) caprylate (Cg) caprate (Cio) isovalerate (branched C5)... 

The uses of caprolactam are described in the section Cyclohexane. Almost 60 percent of the 27 million lb of salicyclic acid went to aspirin, with remainder mainly going to salicylate esters and phenolic resins. Aspirin (acetyl salycylic acid) has long been recognized for its analgesic and antipyretic properties. It must now share this market with the... 

Salicylic esters prepared by [3+3] cycloadditions between l,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes and free or protected 1,3-diketones undergo a Williamson cylisation to yield chroman-8-carboxylate esters (Scheme 12). Application of this methodology to... 

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