Methyl aminophenols

This is based on the reaction of derivatives of pyridine with cyanogen bromide in the presence of an aromatic amine giving specific colors. Amines commonly used are 2-naphthylamine-i-sulfonic acid, />-aminoacetophenone, iV-methyl-aminophenol sulphate, aniline and />-naphthylamine. The reaction gives a yellowish-green color which is measured photometrically. The color is soluble in amyl alcohol which can be used to extract it from water solutions, but is not stable unless a phosphate buffer of pH 6.i is used. This method is not specific for nicotinic acid since other pyridine derivatives and derivatives of nicotinic acid such as trigonelline, nicotinuric acid and nicotine give a similar color. 

Silica Determination in Water Samples Using p-Methyl-Aminophenol Sulfate-NazSOs Complex as a Reducing Agent... 

V,/V-dimethy1amino)pheno1 (177). In addition, 3-aminophenol may be methylated with dimethyl sulfate under neutral conditions, or its hydrochloride salt heated with methanol at 170°C under pressure for 8 h to give the desired product (178). The compound is used primarily as an intermediate in the production of basic (Red 3 and Red 11) and mordant (Red 77) dyes. 

A Methylamino)phenol. This derivative, also named 4-hydroxy-/V-methy1ani1ine (19), forms needles from benzene which are slightly soluble in ethanol andinsoluble in diethyl ether. Industrial synthesis involves decarboxylation of A/-(4-hydroxyphenyl)glycine [122-87-2] at elevated temperature in such solvents as chlorobenzene—cyclohexanone (184,185). It also can be prepared by the methylation of 4-aminophenol, or from methylamiae [74-89-5] by heating with 4-chlorophenol [106-48-9] and copper sulfate at 135°C in aqueous solution, or with hydroquinone [123-31 -9] 2l. 200—250°C in alcohoHc solution (186). 

Acid YeUow 23 (31), commonly known as Tartraziae, stiU maintains sales of nearly 0.5 million /yr ia the United States. It was first discovered ia 1884 and is made by coupling equimolar quantities of diazotized sulfarulic acid to 3-carboxy-l- -sulfophenyl)-5-pyrazolone. Other monoazopyrazolone dyes of commercial importance iaclude Acid YeUow 17 (32) (sulfarulic acid — l-(2,5-dichloro-4-sulfophenyl)-3-methyl-5-pyrazolone and Acid YeUow 40 [6372-96-9] (33) (Cl 18950) (p-aminophenol l-(4-chloro-2-sulfophenyl)-3-methyl-5-pyrazolone) foUowed by esterification of the phenoUc hydroxy group with -toluenesulfonyl chloride. 

Functional amines, e.g., m-aminophenol, 2-methyl-2-chloro-3-aminophenol, and 4-chloro-3-aminophenol, react with 4-methoxybut-3-en-2-one to yield functional lepidine derivatives 230 (62AG161). 

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

Various hydroxyl and amino derivatives of aromatic compounds are oxidized by peroxidases in the presence of hydrogen peroxide, yielding neutral or cation free radicals. Thus the phenacetin metabolites p-phenetidine (4-ethoxyaniline) and acetaminophen (TV-acetyl-p-aminophenol) were oxidized by LPO or HRP into the 4-ethoxyaniline cation radical and neutral V-acetyl-4-aminophenoxyl radical, respectively [198,199]. In both cases free radicals were detected by using fast-flow ESR spectroscopy. Catechols, Dopa methyl ester (dihydrox-yphenylalanine methyl ester), and 6-hydroxy-Dopa (trihydroxyphenylalanine) were oxidized by LPO mainly to o-semiquinone free radicals [200]. Another catechol derivative adrenaline (epinephrine) was oxidized into adrenochrome in the reaction catalyzed by HRP [201], This reaction can proceed in the absence of hydrogen peroxide and accompanied by oxygen consumption. It was proposed that the oxidation of adrenaline was mediated by superoxide. HRP and LPO catalyzed the oxidation of Trolox C (an analog of a-tocopherol) into phenoxyl radical [202]. The formation of phenoxyl radicals was monitored by ESR spectroscopy, and the rate constants for the reaction of Compounds II with Trolox C were determined (Table 22.1). 

Cyclization, 2-mercaptobenzoxazole from o-aminophenol, 30, 57 methyl cyclopropyl ketone from 5-chloro-2-pentanone, 31, 74... 

Wang resin was purchased from Advanced ChemTech (1% DVB, 0.70mmol/g substitution, 100-200 mash, Cat. SA5009). Anhydrous tetrahydrofuran (THF), A/A-dimcthyl-formamide (DMF), methanol, dichloromethane, pyridine, 1,1 -carbonyldiimidazole (CDI), piperazine, homopiperazine, trans-1,4-diaminocyclohexane, 4-(dimethylamino)pyridine (DMAP), succinic anhydride, diglycolic anhydride, 3-methyl-glutaric anhydride, 2-aminophenol, 2-amino-p-cresol, 2-amino-4-tert-butyl phenol, /V-methylmorpholine (NMM), triphenylphosphine, diethyl azodicarboxylate (DEAD), and trifluoroacetic acid (TFA) were purchased from Aldrich Chemical Company, Inc. and used without further purification. PyBOP was purchased from Novabiochem. 

Soil. Phenmedipham degraded in soil forming methyl A-(3-hydroxyphenyl) carbamate and /jj-aminophenol (Hartley and Kidd, 1987). Hydrolysis yields 3-aminophenol (Rajagopal et al, 1984). The reported half-lives in soil ranged from 20 to 26 d (Rajagopal et al., 1989 Worthing and Hance, 1991). 

Benzazinotropones 118a-c (Scheme 28) are synthesized by the reactions of certain 2-methoxy-3-bromotropones (116) with o-aminophenol (117a 91BCJ2131), o-aminothiophenol (117b 61BCJ146), and N-methyl-o-phenylenediamine [117c 89H(29)1459], respectively. 

In contrast to the reactions of pyrans with electrophiles and nucleophiles, oxidations of 2-amino-4H-pyrans are represented by very few examples. Oxidizing of 281 into 2-iminopyrans 296 with chloroanil or dichlor-odicyanoquinone (DDQ) (04JME6299) can be used to protect the amino group in Sandmeyer reaction (297), or to introduce a methyl group into position 4 of pyran 298. The latter is essential because the corresponding acetophenones do not give 298 with MN and aminophenols (Scheme 125). 

A nitro group at the meta position is readily hydrolysed in water to the phenolic group with the formation of the nitro derivative of N-methyl-m-aminophenol (VIII). Since technical dimethylaniline usually contains a certain amount of methylaniline,... 

The betaines 297 are easily prepared from a pyrylium salt and the appropriate 4-aminophenol followed by deprotonation. Typically, 2,4,6-triphenyl-pyridinium iodide and 4-aminophenol give the blue-black betaine (297 R = R = Ph, R = H) which also occurs as a red hexahydrate. With methyl iodide this compound gives 7V-(p-methoxyphenyl)-2,4,6-triphenyl-pyridinium iodide. 10,221... 

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