Amine picrate salts

The phenethylamine homologue of TMA-6 is well known, but is virtually unexplored pharmacologically. The above benzaldehyde with nitromethane in glacial acetic acid containing ammonium acetate gave the appropriate beta-nitrostyrene as yellow crystals with a mp 177-177.5 °C. This, with LAH in ether, gave 2,4,6-trimethoxyphenethylamine (2,4,6-TMPEA, or 2C-TMA-6) as the picrate salt (mp 204-205 °C) or the hydrochloride salt (mp 234-235 °C). It has been shown not to be a substrate to the soluble amine oxidase from rabbit liver, a property it shares with mescaline, but whether it is or is not active in man is at present unknown. 

Picric acid forms ionic salts with amines, picrates, which are solids of characteristic melting point even though the parent acids are liquids for example, the picrates of m-anisidine, N,N-diethylaniline, and N-methylaniline melt at 169, 142, and 144°. 

Amines (weak base) form salts with picric acid (trinitrophenol), and all amine picrates exhibit an absorption maximum at 359 nm with a molar absorptivity of 1.25 X 10 . A 0.200-g sample of aniline, C6H5NH2, is dissolved in 500 mL water. A 25.0-mL aliquot is reacted with picric acid in a 250-mL volumetric flask and diluted to volume. A 10.0-mL aliquot of this is diluted to 100 mL and the absorbance read at,35, nm in a 1-cm cell. If the absorbance is 0.425, what is the percent purity of the aniline -... 

Tobacco (4) and Atropa belladonna (3) have yielded a third member of this group. It is a component of the volatile tobacco alkaloids and was recovered from this fraction after the triraethylamine had been removed. Preparation dl a number of its crystalline salts and comparison of their melting points by admixture with those from synthetic iV-methylpyrroli-dine completed the identification of this volatile amine. The salts used in this identification were the picrate, m.p. 223-225° (vac), the chloroaurate, m.p. 226° (vac), and the trinitro-m-cresolate, m.p. 171.5-172° (vac). 

Picric acid and the picrate salts of amines absorb at 380 nm with a molar absorptivity of 13,400. An accuracy of +2% was obtained for the spectrophotometric determination of molecular weights of amines [30]. Molecular-weight determinations have been reported of sugars from the absorption spectra of their osazones... 

Dyer, W. J. 1945. Amines in fish muscle I. Colorimetric determination of trimethylamine as the picrate salt./. Fish Res. Board Can. 6 351-358. 

Identification of Amines. Picric acid combines with many amines to give crystalline picrates, of general formula B,(NO )aCeHjOH, where B is a molecule of a monacidic base. These picrates have usually sharp melting- or decomposition-points, and serve to characterise the amines concerned. They may be formed either by (a) direct union of the acid and the base in a suitable solvent, or (6) by the interaction of sodium picrate and a salt of the amine in aqueous solution. 

Note. PRIMARY ALIPHATIC AMINES. The lower amines are gases or low-boiling liquids (b.ps. CHjNH, 7 CiHjNH, 17 CH,(CH2,>,NH 49 (CHg)jCHNHa, 34 ) but may be encountered in aqueous or alcoholic solution, or as their crystalline salts. They are best identified as their benzoyl, or toluene-/>-sulphonyl derivatives (c/. (C) above), and as their picrates when these are not too soluble. This applies also to benzylamine, CjHsCHjNH, b.p. 185 also to ethylenediamine, usually encountered as the hydrate, NHj (CHj)j NH2,HjO, b.p. 116 , for which a moderate excess of the reagent should be used to obtain the di-acyl derivative. (M.ps., pp. 55 55 )... 

This change in editorial leadership has resulted, perhaps inevitably, in a change in editorial policy which is reflected in the contents of Volume 8. There has been a marked de-emphasis on the inclusion of organic parent compounds followed by an exhaustive and voluminous cataloging of azide, azido, azo, diazido, diazonium, diazo, nitro, dinitro, polynitro, hitr amine, nitrate (esters and salts), dinitrate, poly nitrate, nitroso, polynitroso, chlorate, perchlorate, peroxide, picrate, etc, derivatives — regardless of whether any of these derivatives exhibit documented explosive or energetic properties. Only those materials having such properties have been included in this volume... 

Picric acid, in common with several other polynitrophenols, is an explosive material in its own right and is usually stored as a water-wet paste. Several dust explosions of dry material have been reported [1]. It forms salts with many metals, some of which (lead, mercury, copper or zinc) are rather sensitive to heat, friction or impact. The salts with ammonia and amines, and the molecular complexes with aromatic hydrocarbons, etc. are, in general, not so sensitive [2], Contact of picric acid with concrete floors may form the friction-sensitive calcium salt [3], Contact of molten picric acid with metallic zinc or lead forms the metal picrates which can detonate the acid. Picrates of lead, iron, zinc, nickel, copper, etc. should be considered dangerously sensitive. Dry picric acid has little effect on these metals at ambient temperature. Picric acid of sufficient purity is of the same order of stability as TNT, and is not considered unduly hazardous in regard to sensitivity [4], Details of handling and disposal procedures have been collected and summarised [5],... 

Pyridines form stable salts with strong acids. Yellow ionic picrates were used for characterization in the past. Pyridine itself is often used to neutralize acid formed in a reaction and as a basic solvent. The basicity of pyridine (as measured by the dissociation constant of its conjugate acid, pKa 5.2) is less than that of aliphatic amines (cf. NH3, pA"a 9.5 NMe3, pKd 9.8). This reduced basicity is probably due to the changed hybridization of the nitrogen atom in ammonia the lone electron pair is in an sp3-orbital, but in pyridine it is in an s/r-orbital. The higher the s character of an orbital, the more it is concentrated near the nucleus, and the less available for bond formation. Nitriles, where the lone electron pair is in an. vp-orbital, are of even lower basicity. 

Many aziridines form picrates and other salts which are stable in the crystalline state. - 4 Attempts to rocrystallize such compounds frequently result in decomposition. The quaternary azjridinium salts (XLII) are somewhat more stable, and have been much studied in connexion with the reaction of the jU-chloroalkyl tertiary amines ( nitrogen mustards ). 

Alkylomines, Alkylarylwninos, Arylomines ond Their Explosive Derivotives. Alkylamines alkyl aryl amines and arylamines may form nitrocompds as well as various salts of which the nitrates, perchlorates and picrates may... 

Picric acid combines with amines to yield salts (picrates), which usually possess characteristic melting points. Most picrates have the composition 1 mol amine 1 mol picric acid. The picrates of the amines, particularly of the more basic ones, are generally more stable than the molecular -complexes formed between picric acid and the hydrocarbons (compare Section 9.6.3, p. 1238). 

Picrates, especially salts of transition and heavy metals, such as nickel, lead, mercury, copper, and zinc picric acid is explosive but is less sensitive to shock or friction than its metal salts, and is relatively safe as a water wet paste Polynitroalkyl compounds, such as tetranitromethane and dinitroacetonitrile Polynitroaromatic compounds, especially polynitrohydrocarbons, phenols, and amines... 

Excellent examples of this reaction are found in the preparations of acetamidine (91%) and nicotinamidine (60%). The conversion is accomplished by treatment of the imino ester hydrochloride with alcoholic ammonia or by the action of ammonium chloride on the free imino ester. The amidines are frequently isolated as salts such as the sulfates or picrates. N-Substituted amidines result when amines are used in place of ammonia. ... 

Dissolve 30 mg of moist (35% water) picric acid in 0.25 mL of methanol and to the warm solution add 10.1 mg of triethylamine and let the solution stand to deposit crystals of the picrate, an amine salt that has a characteristic melting point. This picrate melts at 171°C. 

Several attempts were made to isolate the amine oxide as a hydrochloride salt. Usually the salt did not crystallize, but a hygroscopic oil resulted on evaporation of the solvent. Isolation was simplifled by using picric acid, for the picrates crystallized on standing. 

The reagent has been used for the cleavage of picric acid salts of amines. The finely divided yellow picrate is shaken with a mixture of ether and a concentrated aqueous solution of ethanolamine, and the ether solution is drawn off and extracted repeatedly with ethanolamine solution until it is no longer colored. Hiinig and Baron studied the velocity of splitting of quaternary ammonium salts on refluxing with ethanolamine. ... 

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