Acids 4-hydroxyphenylacetic acid

Fio. 36. Vloi t Hoff plou of the retention bctors of aromatic acids in reversed-phase chromatography using octadecyl silica as the stationaiy phase and neat aqueous 30 taM NaHiPO buffer (pH 2.0) (open symbols), or the same buffer containing 696 (v/v) of aceloni ti (closed symbols) as the eluent. Column S imSpherisorbODS, 230 x 4.6 mm. Eluites 3.4xlihydroxymandelic acid (O. ) 4 hydroxymandelic acid ( , ) 4-hydroxyphenylacetic acid (7. ) 3,4-dihydroxyphenylacetic acid (A, A). Reprinted with permission from Me-lander tt at. U77). 

Other phenolic acids and derivatives 4- (Acetoxythyl) -1,2 -dihydroxybenzene Dopac (3,4-dihydroxyphenylacetic acid) 4-hydroxyphenylacetic acid COOH HO- HO Lignans (+)-l-Acetoxypino resinol (+)-Pinoresinol, / (+)-Hydroxypinoresinol "7 WR OCH3 HO OCH3... 

The test sample to use in qualification should be a small molecule that is soluble in water, has a strong UV chromophore, and possesses a charge at the intended separation pH value. A nonvolatile compound is also desirable, especially when used for assessing peak area reproducibility during the detector linearity test. Some examples of test samples that can be used are benzoic acid, 4-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, and 4-hydroxyacetophenone. 

Carboxylic acids, acyl chlorides, and sulfonyl chlorides used for deri-vatization of 4-aminophenylalanine and >-4-am i n op h e ny I a I a n i n e are as follows 5-hydantoinacetic acid, / ran, v - 4 - co t i n i n ec a r b o xy I i c acid, isonicotinic acid, 3-pyridinepropionic acid, 4-hydroxyphenylacetic acid, 2-butynoic acid, 2-pyrazinecarboxylic acid, cyclopropanecarboxylic acid, 3-hydroxy-2-qui-noxaline carboxylic acid, 5-bromovaleric acid, propargyl chloroformate, 3,4-dimethoxybenzoyl chloride, 2-thiophenesulfonyl chloride, 3-thiophene-carboxylic acid, 2-thiophenecarboxylic acid, 2-methylbutyric acid, 2-thio-pheneacetyl chloride, benzoic acid, furylacrylic acid, 4-nitrophenyl acetic acid, 2,5-dimethoxyphenylacetic acid, p-toluenesulfonyl chloride, 4-(di-methylamino)phenylacetic acid, 3-indolepropionic acid, phenoxyacetic acid, 3-(dimethylamino)benzoic acid, cyclohexanecarboxylic acid, naphtha-lenesulfonyl chloride, 4-bromophenylacetic acid, 4-bromobenzoic acid, 2-phenoxybutyric acid, 3,4-dichlorophenylacetic acid, (l-naphthoxy)acetic acid. 

Trimethoxybenzoic acid, 4-hydroxyphenylacetic acid, salicylic acid, ferulic acid, p-coumaric acid, vanillic acid, 4-hydroxybenzoic acid... 

The early studies of phenohc compounds have been carried out in 1965 [41] and in 1978 [42]. They reported on phloroglucin, protocatechuic acid, 4-hydroxybenzoic acid, syringic acid, vanillic acid, phenylacetic acid, 4-hydroxyphenylacetic acid, and 2-hydroxyphenylacetic acid. 

Phenolics Phleum pratense Epichloe typhina -hydroxybenzoic acid, -hydroxyphenylacetic acid, tyrosol, cis-and tranS p CoumaFic acid 246... 

With this resin DL-mandelic acid (hydroxyphenylacetic acid) (1) could be partially resolved if dioxane or mixtures consisting of chloroform and methanol were used as eluant. Quantitative investigations showed that the mandelic acid was recovered completely and that the antipodes were partially enriched in subsequent fractions of the eluate in equi-... 

Hydroxyphenylacetic acid [614-75-5] M 152.2, m 148-149", b 240-243"/760mm, pKEst(i)-4.3, pKEst(2)-10.1. Crystd from ether or chloroform (m from latter is always lower). 

The synthesis and metabolism of trace amines and monoamine neurotransmitters largely overlap [1]. The trace amines PEA, TYR and TRP are synthesized in neurons by decarboxylation of precursor amino acids through the enzyme aromatic amino acid decarboxylase (AADC). OCT is derived from TYR. by involvement of the enzyme dopamine (3-hydroxylase (Fig. 1 DBH). The catabolism of trace amines occurs in both glia and neurons and is predominantly mediated by monoamine oxidases (MAO-A and -B). While TYR., TRP and OCT show approximately equal affinities toward MAO-A and MAO-B, PEA serves as preferred substrate for MAO-B. The metabolites phenylacetic acid (PEA), hydroxyphenylacetic acid (TYR.), hydroxymandelic acid (OCT), and indole-3-acetic (TRP) are believed to be pharmacologically inactive. 

CiiHiyN O 76610-81-6) see Cetbuperazone 0( -)< a>(2t3 dioxo-4 ethyl l>piperazmocarbonylamino) 4-hydroxyphenylacetic acid... 

Oxidant production is measured with the fluorogenic substrate para-hydroxyphenylacetic acid (PHPA) in the presence of superoxide dismutase and peroxidase (9). Under these conditions, superoxide is converted to H2O2 by the superoxide dismutase, and two molecules of PHPA are converted to a fluorescent diadduct by H2O2 and peroxidase. Similar assays have been devised using homovanillic acid (16) or scopoletin (17) instead of PHPA. 

Sparnins VL, PJ Chapman, S Dagley (1974) Bacterial degradation of 4-hydroxyphenylacetic acid and... 

Brachiaria mutica, dried leaves Vanillic, p-hydroxybenzoic, o-hydroxyphenylacetic acids 74... 

Panicum maximum, dried leaves p-Hydroxyphenylacetic acid 74... 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

Creosol (also called 2-methoxy-jb-cresol, 4-methylguaiacol, and 3-methoxy-4-hydroxytoluene) has been obtained by the fractionation of beach creosote tar,4 by the reduction of vanillin by electrolytic methods,6 6 by hydrogen and palladium on charcoal or barium sulfate,7 8 with hydrazine,9 and by amalgamated zinc and hydrochloric acid.3 10 11 It has also been prepared by methyl-ation of 4-methylcatechol with methyl iodide 12 13 or with methyl sulfate 14 and is reported to be formed by the distillation of the calcium salt of 3-methoxy-4-hydroxyphenylacetic acid.16... 

Metabolites of biogeiuc amines have also been analyzed by GC-ECD. For the simultaneous analysis of 5-hydroxyindole-3-acetic acid (5-HIAA), homovanillic acid (HVA) and m- and p-hydroxyphenylacetic acid (m-, p-HPAA), (metabolites of 5-HT, DA, and m- and p-tyramine acid respectively) in urine, a simple acidic extraction followed by derivatization with PFPA (derivatizes phenols) and hexafluoroisopropanol (deriva-tizes carboxylic acid groups) has been used (Davis et al., 1982 Baker et al., 1987). 

A number of different reaction conditions were investigated for the Mitsunobu reaction and DIAD/PPh3 proved to be the most efficient combination of reagents. The dendronized support was then compared with the conventional TentaCel resin keeping the scaffold on the resin constant (glycine and 4-hydroxyphenylacetic acid) and employing four different alcohols. Much better yields were obtained... 

Gracin, S. and Rasmuson, A.C. Solubility of phenylacetic acid, p-hydroxyphenylacetic acid, p-aminophenylacetic acid, p-hydroxybenzoic acid, and ibuprofen in pure solvents, / Chem. Eng. Data, 47(6) 1379-1383, 2002. 

The authors report detection limits of 8x10 ° mol/dm for TATP and 8 X lO mol/dm for HMTD. When p-hydroxyphenylacetic acid (p-HPAA) (6) was used as the oxidation substrate instead of ABTS, a highly fluorescent dimer (7) was formed. This dimer could be detected spectrophotometricaUy, although the sensitivity dropped (Eq. (12)). Both methods also enabled a semi-quantitative estimation of TATP and HMTD concentrations [86]. Dimerization of p-hydroxyphenylacetic acid (p-HPAA) by hydrogen peroxide in presence of peroxidase [86] is as foUows ... 

Aryl esters of 4-hydroxyhutyric acid, 5-hydroxyvaleric acid, 2-hydroxyphenylacetic acid, and 3-(2-hydroxyphenyl)propionic acid lactonize with rate constants proportional to (Capon et... 

---