Salicylic acid chemical structure

Chemical Name 2, 4 -Difluoro4-hydroxy-[ 1,1 -biphenyl] -3<arboxylic acid Common Name Difluorophenyl salicylic acid Structural Formula cooh... 

NSAIDs are of diverse chemical structures salicylates (aspirin, sulphasalazine), indole acetic acids (indomethacin, etodolac), heteroaryl acetic acids (diclofenac), arylpropionic acids (ibuprofen, naproxen), anthranilic acids (mefenamic acid) and enolic acids (piroxicam, meloxicam). 

Fig. 3.ia-c. Chemical structures of Jessner s Peel components (a Salicylic acid, b Resorcinol, and c Lactic acid)... 

Only four years after Kekule proposed the ring structure for benzene, and before the configuration of salicylic acid was established, Kraut concluded on the basis of sound chemical evidence that the products obtained on heating acetylsalicylic acid possess chain structures formed through intermolecular esterification. He assigned the dimeric and tetrameric formulas... 

The chemical structures of the majority of FMs that have been studied in wastewater treatment are given in Figs. 1-3. Figure 1 shows a variety of FM structures that include alcohols, aldehydes, and ketones, including benzyl acetate (phenylmethyl ester acetic acid), methyl salicylate (2-hydroxy-methyl ester benzoic acid), methyl dihydrojasmonate (3-oxo-2-pentyl-methyl ester cyclopentaneacetic acid), terpineol (4-trimethyl-3-cyclohexene-1-methanol), benzyl salicylate (2-hydroxy-phenylmethyl ester benzoic acid), isobornyl acetate... 

Spectroscopic techniques may provide the least ambiguous methods for verification of actual sorption mechanisms. Zeltner et al. (Chapter 8) have applied FTIR (Fourier Transform Infrared) spectroscopy and microcalorimetric titrations in a study of the adsorption of salicylic acid by goethite these techniques provide new information on the structure of organic acid complexes formed at the goethite-water interface. Ambe et al. (Chapter 19) present the results of an emission Mossbauer spectroscopic study of sorbed Co(II) and Sb(V). Although Mossbauer spectroscopy can only be used for a few chemical elements, the technique provides detailed information about the molecular bonding of sorbed species and may be used to differentiate between adsorption and surface precipitation. 

If youve got a headache by now, you might take some acetyl salicylic acid. Thats aspirin, and it has the chemical structure ... 

The complexes [Ru(bpy)2L]+ (HL = acetylacetone, trifluoroacetylacetone, hexafluoroacetylace-tone, tropolone or dibenzoylmethane) have been prepared and characterized they act as catalysts for the oxidation of alcohols, 3,5-di-tert-butylcatechol and alkanes in the presence of appropriate co-oxidants." Perchlorate salts of [Os(bpy)2L] in which HL = salicylaldehyde, 2-hydroxyaceto-phenone or 2-hydroxynaphthaldehyde, are formed from reactions of [Os(bpy)2Br2] with HL. The structure of the salicylaldehyde derivative has been determined. Chemical and electrochemical oxidations of [Os(bpy)2L]" yield the corresponding low-spin Os species from which [Os(bpy)2L]+ can be regenerated." " [Ru(bpy)2L]" (HL = salicylic acid) has been prepared and structurally characterized as the tetrahydrate. Absorptions at 590 nm, 400 nm, and 290 nm in the electronic spectrum have been assigned to Ru bpy CT transitions electrochemical oxidations of the complex have been investigated." ... 

Figure 1.13. Chemical structure of salicin, salicylic acid and acetylsalicylate...

Chemical structures of salicylic acid (a) and para-hydroxybenzoic acid (b). 

Obviously, a large number of compounds would seem to fit these two definitions. (Salicylic acid and galacturonic acid, for example, would fit the solubility parameters for soil humic and fulvic acids, respectively.) However, the added restrictions of elemental analysis (see Table 1)—dark color (e.g., absorption spectra) titration data, and molecular weight—would narrow the possible chemical structures. 

Chemical compound entity extraction is a different type of entity extraction. One cannot refer to a complete dictionary or thesaurus of chemical compound names, as there is practically an infinite number of compound names. Systematic names, such as the International Union of Pure and Applied Chemistry (IUPAC) nomenclature system [54], are created from a set of rules that determine the name of a chemical compound based on the chemical structure. As an example we show aspirin, which has the common chemical name acetyl salicylic acid and the IUPAC name 2-acetyloxybenzoic acid. The common names, including aspirin, can be found using a thesaurus-based approach with low levels of ambiguity. The IUPAC name is a systematically determined name that must be tagged in the text using a heuristics-based approach (rules based). In many cases, one will have only the IUPAC name, not a known common name, for a compound. 

A second approach involves modification of the chemical structure of ALA itself by turning it into an ester. This is somewhat reminiscent of the topical use of methyl salicylate (the methyl ester of salicylic acid) which releases salicylic acid in vivo following enzymatic cleavage of the ester bond. Certain esters of ALA can penetrate the skin more rapidly than ALA itself (presumably because the esters are more hydrophobic), and then subsequently release ALA in vivo following cleavage by tissue esterases. It certainly would be an advance if the use of such pre-ALA compounds increased the depth at which ALA-PDT was effective [155-159]. While the hexyl ester derivative of ALA seems to show better membrane penetration properties and improved PpIX production than other esters [159], a current drawback is the significantly greater toxicity of the hexyl ester compared with ALA itself. While there are still some problems to be worked out, derivatives of ALA may well prove useful in ALA-PDT. 

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