Salicylic stabilizer

The photostabilizer must be durable. It was found that salicylic stabilizers are efficiently degraded by singlet oxygen in polar alkaline media but in a less polar, non-aUcaline solvents these stabilizers are durable." In hydrogen-bonding solvents, the absorption spec-tmm of UV absorbers is changed. ... 

Salicylate anion is a weaker base than p hydroxybenzoate because it is stabilized by intramolecular hydrogen bonding... 

As a pharmaceutical, methyl salicylate is used in liniments and ointments for the relief of pain and for rheumatic conditions. As a flavor and fragrance agent, it is used in confectioneries, dentifrices, cosmetics, and perfumes. Other commercial applications for methyl salicylate are as a dye carrier, as a uv-light stabilizer in acrylic resins, and as a chemical intermediate. The May 1996 price was 5.50/kg (18). 

Further improvement in light stability may be achieved by addition of small quantities of ultraviolet absorbers. Typical examples include phenyl salicylate, 2,4-dihydroxybenzophenone, resorcinol monobenzoate, methyl salicylate and stilbene. 

UV absorbers have been found to be quite effective for stabilization of polymers and are very much in demand. They function by the absorption and harmless dissipation of the sunlight or UV-rich artificial radiation, which would have otherwise initiated degradation of a polymer material. Meyer and Geurhart reported, for the first time in 1945 [10], the use of UV absorber in a polymer. They found that the outdoor life of cellulose acetate film was greatly prolonged by adding phenyl salicylate (salol) [10]. After that, resorcinol monobenzoate, a much more effective absorber, was introduced in 1951 [11] for stabilization of PP, but salol continued to be the only important commercial stabilizer for several years. The 2,4-dihydroxybenzophenone was marketed in 1953, followed shortly by 2-hydroxy-4-methoxybenzophenone and other derivatives. Of the more commonly known UV absorbers, the 2-hydroxybenzophenones, 2-hy-droxy-phenyl-triazines, derivatives of phenol salicylates, its metal chelates, and hindered amine light stabilizers (HALS) are widely used in the polymer industry. 

Discussion. Salicylic acid and iron(III) ions form a deep-coloured complex with a maximum absorption at about 525 nm this complex is used as the basis for the photometric titration of iron(III) ion with standard EDTA solution. At a pH of ca 2.4 the EDTA-iron complex is much more stable (higher stability constant) than the iron-salicylic acid complex. In the titration of an iron-salicylic acid solution with EDTA the iron-salicylic acid colour will therefore gradually disappear as the end point is approached. The spectrophotometric end point at 525 nm is very sharp. 

Treating petroleum oils with 3-5% calcium alkyl salicylate and 0.5-3% triethanolamine salts of phosphoric acid esters and ethoxylated dodecyl alcohol increases oxidation-thermal stability at 180-200°C in the manufacture of oil for metal parts quenching. The agent provides also short-term anticorrosion protection of the hardened articles [261]. Phosphoric acid salt alkyl esters are used in anticorrosives and aqueous dispersions in waterborne polyester coatings for metals [244]. 

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. 

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. 

Stability constants, measured in methanol solution, for alkaline earth complexes of a number of ionophores are given in Table XVI (280,289,571-577).8 The values for the complexes of valinomycin and enniatin B lie between the values for the crown ethers 15C5 and 18C6 (cf. Section II.C.5 above), for the middle four entries the values are slightly higher. Stabilities of enniatin B complexes show a modest maximum for Ca2+, and of valinomycin complexes show stabilities increasing up to Ba2+ (281). LogAi values for the Ca2+ complexes of acetate, benzoate, and salicylate are between 4.5 and 4.7 in methanol (578) - the... 

It is easily forgotten that aspirin degrades to acetic as well as salicylic acid. And, indeed, any smell aspirin might have is due to acetic acid. However, the volatility of acetic acid does not make the determination of acetic acid a reliable tool to measure stability or degradation. 

Alagona, G. and Ghio, C. Stability and acidity of salicylic acid rotamersin aqueous solution. A... 

Isopropylphenyl acrylate, in VDC polymer stabilization, 25 721 Isopropylphenyl diphenyl phosphate, 7 7 494 2-Isopropylquinoline, 27 189 Isopropyl salicylate, physical properties of, 22 14t... 

Phosphine complexes, osmium, 19 642 Phosphine coordination complexes, of uranium, 25 436 Phosphine derivatives, 19 28 Phosphine oxide(s), 11 495-496 19 66 predicted deviations from Raoult s law based on hydrogen-bonding interactions, 8 814t in salicylic acid manufacture, 22 8 Phosphine oxide diols/triols, 11 501 Phosphine selenides, 22 90 Phosphinic acid, 19 20, 54-55 Phosphinic anhydride, 11 499 Phosphinothricin acetyltransferase (PAT) proteins, 13 360 Phosphite esters, 19 20 Phosphites, in VDC polymer stabilization, 25 720... 

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