Phenols crystalline derivatives

Urethane formation. See (C) below. This reaction should be used for crystalline derivative formation, and not as a general reaction for phenols. 

Crystalline derivatives, suitable for identification and characterisation are dealt with in Section IV, 114, but the preparation of the following, largely liquid, derivatives will be described in the following Sections. When phenols are dissolved in aqueous sodium hydroxide solution and shaken with acetic anhydride, they undergo rapid and almost quantitative acetylation if the temperature is kept low throughout the reaction. This is because phenols form readily soluble sodium derivatives, which react with acetic anhydride before the latter undergoes appreciable hydrolysis, for example ... 

Perhaps the most that can be said for this method is that it has been neglected in favor of more reliable methods and that it might at least be tried when other methods have failed. Many phenols and alcohols are crystalline or form a variety of crystalline derivatives that could be tested without great difficulty. 

Adifoline is an amphoteric substance, which contains one carboxylic acid group one other acidic grouping is present, probably as a phenolic hydroxyl group, since adifoline gives a (gummy) dimethyl derivative with diazomethane. Attempts to characterize adifoline as a salt also failed, since no crystalline derivatives could be obtained (37). 

In general a much wider use has been made of electrophilic substitution reactions with t-octylphenol from the reaction of diisobutene with phenol and rather less applications in the field of polymer chemistry. Thus for example, estenfication, nitration, phosphorylation, diazotisation, chlorination, sulphation, carboxylation, formylation and etherification have led to well-characterised derivatives (ref.93). Unlike t-nonylphenol, t-octylphenol [4-(1,1,3,3-tetra-methylbutyOphenoQ is a crystalline compound yielding characteristic crystalline derivatives as can be seen in the following instances. t-Nonylphenol by contrast is a mixture of sidechain isomers although predominantly a p-substituted compound. Its heterogeneity like that of many technical product undoubtedly enhances its physical properties in many of its industrial applications. Thus for... 

There are a number of well-known colour tests for monosaccharides, such as condensation of the acid degradation products with phenolic substances. Perhaps the most frequently cited example of this is the Molisch test in which carbohydrates give a purple colour with a-naphthol in the presence of concentrated sulphuric acid. The presence of ketoses and of 3,6-anhydro-hexoses is often detected by the characteristic red colour rapidly developed with acid resorcinol (Seliwanoff test), and the presence of 2-deoxypentoses may be shown by the deep blue colour they yield with diphenylamine after degradation with acid to 5-hydroxy-levulinaldehyde. Before an individual sugar can be identified, however, it must be isolated as a pure substance in crystalline form or converted to a characteristic crystalline derivative. The derivative the author considers the best for the characterisation of the better known monosaccharides is given in Table I (p. 57). 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

These are crystalline compounds with sharp melting points, and possess the further advantage that their equivalent weights may be determined by dissolving in dilute alcohol and titrating with standard alkali. Nitro-phenols, however, give unsatisfactory derivatives. 

Sulfonamides (R2NSO2R ) are prepared from an amine and sulfonyl chloride in the presence of pyridine or aqueous base. The sulfonamide is one of the most stable nitrogen protective groups. Arylsulfonamides are stable to alkaline hydrolysis, and to catalytic reduction they are cleaved by Na/NH3, Na/butanol, sodium naphthalenide, or sodium anthracenide, and by refluxing in acid (48% HBr/cat. phenol). Sulfonamides of less basic amines such as pyrroles and indoles are much easier to cleave than are those of the more basic alkyl amines. In fact, sulfonamides of the less basic amines (pyrroles, indoles, and imidazoles) can be cleaved by basic hydrolysis, which is almost impossible for the alkyl amines. Because of the inherent differences between the aromatic — NH group and simple aliphatic amines, the protection of these compounds (pyrroles, indoles, and imidazoles) will be described in a separate section. One appealing proj>erty of sulfonamides is that the derivatives are more crystalline than amides or carbamates. 

S. Henningsii (S. Africa). Two crystalline alkaloids (1) 23 28 5 2> m.p. 280-5-282°, [a]], ° — 80° (EtOH) contains one methoxyl, but no methylimino group and is possibly phenolic (2) 24 3305 2> m.p. 214-5-215°, contains two methoxyl groups and gives a violet coloration with Frohde s reagent. The alkaloids are possibly mono-and di-methoxy derivatives of the same parent base. Amorphous alkaloids are also present and possibly a third crystalline base (Rindl, S, Afr. J. Sci., 1929, 26, 50 Trans. Boy. Soc. S, Africa, 1931, 20, 59 (with Sapiro), ibid., 1936, 23, 361). 

This phenolic ether, CgH3(OH)(OCH3)2, has been identified in the essential oil of an Algerian plant, whose botanical source is not identified. It is a crystalline body melting at 51°, and yields a benzoyl derivative melting at 107° to 108°. 

The direct bromination of aniline and phenol derivatives in solution results in polybromination to give a complex mixture. But bromination by gas-solid and solid-solid reactions proceeds more efficiently and selectively. Bromination by gas-solid reaction can be accomplished through a very simple procedure. For example, the powdered crystalline aniline 13 and Br2 were placed in... 

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