Salicylic acids varieties

As of 1991 in the United States, OTC antiacne preparations may contain only a few active dmgs, for example, sulfur [7704-34-9] resorcinol acetate [102-29-4], resorcinol [108-46-3], salicylic acid [69-72-7], and some combinations (52). OTC anti-acne constituents maybe included in a variety of conventional cosmetic preparations, which then become OTC dmgs. These include lotions, creams, solutions, facial makeups, facial cleansers (including abrasive cleansers), and astringents. Products must contain the specified dmgs at the designated concentrations. Compositions of antiacne products have beenpubhshed (53). 

Phenolic resins were the first totally synthetic plastics invented. They were commercialized by 1910 [I]. Their history begins before the development of the structural theory of chemistry and even before Kekule had his famous dreams of snakes biting their tails. It commences with Gerhardt s 1853 observations of insoluble resin formation while dehydrating sodium salicylate [2]. These were followed by similar reports on the behavior of salicylic acid derivatives under a variety of reaction conditions by Schroder et al. (1869), Baeyer (1872), Velden (1877), Doebner (1896 and 1898), Speyer (1897) and Baekeland (1909-1912) [3-17]. Many of these early reports appear to involve the formation of phenolic polyesters rather than the phenol-aldehyde resins that we think of today. For... 

A variety of formulations of salicylic acid have been used as peeling agents. These include 50% ointment formulations (Table 6.1) [2,3], as well as 10, 20 and 30% ethanol formulations (Table 6.2) [4,6]. More recently, commercial formulations of salicylic acid have become available (BioGlan Pharmaceuticals Company, Malvern, PA Bionet Esthetics, Little Rock, AR). 

Ethanol formulations of salicylic acid (20 and 30%) are used for combination peeling (see salicylic acid section). Trichloroacetic acid is prepared as an aqueous solution, since ethanol solutions do not penetrate the skin. It is prepared by mixing the appropriate concentration of crystals with up to 100 cc of distilled water. Ten and fifteen percent TCA is prepared by mixing 10 or 15 g of crystals in up to 100 cc of total volume, respectively. Aqueous solutions of TCA remain stable for up to 6 months unless contaminated. Other methods have been used to formulate TCA peeling solutions however, the weight/volume methods appear to be the most reliable formulation [5]. Premixed TCA solutions are available from a variety of medical... 

Essentially, all methods of synthesis are variations of the reaction of acetylchloride, acetic anhydride or ketene11 with salicylic acid using a variety of catalysts such as pyridine12 or sulfuric acid13 and reaction conditions (c.f. 14). The preparation of aspirin labeled with a i4c iaj-,eie(j acetyl group has also been reported.15 Efforts to improve the commercial processes continue to the present day. 

A variety of hydrolases catalyze the hydrolysis of acetylsalicylic acid. In humans, high activities have been seen with membrane-bound and cytosolic carboxylesterases (EC 3.1.1.1), plasma cholinesterase (EC 3.1.1.8), and red blood cell arylesterases (EC 3.1.1.2), whereas nonenzymatic hydrolysis appears to contribute to a small percentage of the total salicylic acid formed [76a] [82], A solution of serum albumin also displayed weak hydrolytic activity toward the drug, but, under the conditions of the study, binding to serum albumin decreased chemical hydrolysis at 37° and pH 7.4 from tm 12 1 h when unbound to 27 3 h for the fully bound drug [83], In contrast, binding to serum albumin increased by >50% the rate of carboxylesterase-catalyzed hydrolysis, as seen in buffers containing the hydrolase with or without albumin. It has been postulated that either bound acetylsalicylic acid is more susceptible to enzyme hydrolysis, or the protein directly activates the enzyme. 

Methods for analysis of analgesics including salicylic acid and acetylsal-icylic acid (567) in combination with a variety of other active ingredients have been reported 068). Antipyrine and benzocaine in eir drops have been determined by RPC and the method was found to be four to. six times imiic lapul Ilian llic licsl allei native (569). Salicylic acid and benzoic acid haVe also been assayed in ointments (576). 

The first case study we will consider is the assay of aspirin together with its major degradation product salicylic acid [19], This application study was selected as the HPLC assay of aspirin is well covered in the literature and we could select factors to test from the variety of HPLC conditions used in these published methods. This test was performed using a reflected saturated factorial design requiring a total of 15 experiments. 

That s quite a claim for the little pill that was concocted in 1897 by Felix Hoffmann, a chemist working for the Bayer company in Germany. While Hoffmann did synthesize the first commercial sample of acetylsalicylic acid, as aspirin is known generically, he wasn t the first to produce the substance in the laboratory. That honor goes to Karl Friedrich Gerhardt, who, in 1853 at Montpellier University in France, concocted an impure version with an eye towards improving on the effects of salicylic acid, a commonly used painkiller. At the time salicylic acid was extracted from the leaves of the meadowsweet plant and used for the treatment of fevers and pain, particularly of the arthritic variety. But it had to be taken in... 

The product of step o is known as isochoris-mate.55 56 Isochorismate gives rise to a variety of products including vitamin K, salicylic acid,56a the iron chelator enterobactin (Fig. 16-1), and other siderophores. These are formed in E. coli via 2,3-dihy-droxybenzoate as indicated in Fig. 25-2.57-59a The genes (ent) for the requisite enzymes are clustered at 14 min on the E. coli chromosome map (Fig. 26-4). 

Benzoic and salicylic acids. Two of the simplest plant acids arising from fraus-cinnamate are benzoic acid, accumulated in plums and cranberries, and salicylic acid, present in all green plants and accumulated as methyl esters or glycosides in some plants, e.g., those of the willow family. Salicylic acid is made by hydroxylation of benzoic acid,177 which can be formed from frans-cinnamate by P oxidation as depicted in Fig. 25-8, but it may also arise from isochoris-mate as shown in Fig. 25-2.178 Salicylic acid plays a central role in resistance of plants to a variety of... 

Complex formation of nickel(II) with a variety of hydroxy acids has been investigated. It has been reported that in aqueous solution in the pH range 6-7.2 at 25 °C, a 1 1 neutral complex is formed between nickel(II) and the salicylato monoanion, HOCsH Oj (Keq —1.4 x 10 6), or its 5-substituted analogue, with the further release of a proton.1789,1790 The effects of substituents on the stability constants of nickel complexes with various 4- and 5-substituted salicylic acids were also studied.1791,1792... 

Carreira and co-workers reported novel Ti(lV) complexes 69 derived from Ti(0 Pr)4, tridentate ligands 67, and salicylic acids such as 68. The complexes serve as competent catalysts for the addition of the methyl acetate-derived silyl ketene acetal to a large range of aldehydes (Eqs. 8B2.16 and 8B2.17) [22]. The salient features of this system include the wide range of functionalized aliphatic and aromatic aldehydes that may be used the ability to carry out the reaction with 0.2-5 mol % catalyst-loading and experimental ease with which the process is executed (Table 8B2.8). Thus the reaction can be carried out at -10 to 0°C, in a variety of solvents, without recourse to slow addition of reagents. The adducts from the catalytic reaction were isolated with excellent enantiopurities up to 99% ee. The original catalyst-preparation... 

On developing easy access to a variety of 6-alkyl salicylic acids, Shirai and co-workers found that the methoxy group of 3-butyl-7-methoxyphthalide (3) was cleanly cleaved during AICI3 (5 equiv.)-promoted displacement with butanethiol at room temperature the product was the phenol 4 [17]. When the reaction was performed at... 

The usual Kjeldahl procedure works for a large variety of nitrogen compounds such as amines, amino acids, and alkaloids, but fails for nitrates, nitrites, azo compounds, cyanides, and derivatives of hydrazine. For nitrates a method involving the addition of salicylic acid may be used. Azo compounds give quantitative results if first reduced by refluxing with tin(II) chloride and hydrochloric acid. Hydrazine derivatives are decomposed by heating with formaldehyde, zinc dust, and hydrochloric acid, followed by tin(II) chloride, prior to the usual Kjeldahl digestion. ... 

Natural nicotine is the levo variety. Physiologically the alkaloid affects both the central and peripheral nerves and increases the activity of the secreting glands. In more than minimum doses it is a poison. It is not used to any extent in medicine though recently it has been suggested as a hypodermic in cases of tetanus. The salicylic acid salt is also used somewhat for skin diseases. Tobacco extracts and also powdered tobacco are used as insecticides, their value depending upon the amount of nicotine present. I... 

In insects, glycine is the amino acid of choice for xenobiotic conjugation and glycine conjugates of a variety of substituted benzoic acids ( -aminobenzoic acid, -nitrobenzoic acid, salicylic acid and anthranilic acid) have been reported in the housefly (M-domestica), mosquito (Aedes sp.), locust (L. gregaria) and silkworm II. mori) (3,4,6,7,37). 

The fact that the presence of the hydroxy function originating from the salicylic acid is an essential requirement for cestodicidal and flukicidal activity, led Hoechst scientists to prepare a variety of 2,6-dihydroxybenzoic acid anilides. The most effective compound of the series were 4 -chloro/bromo-6-hydroxysalicy-lanilides (5a,b). Of these, the bromo analogue, called resorantel (terenol, 5b) was found to be more effective than the 4 -chloro analogue (5a) [12]. Resorantel was later... 

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