Hydroxy-, derivatives solubility

The mechanism of cyclization of diaminopyrimidines by nitrous acid appears not to have been studied in detail. For the preparative procedure an aqueous solution of alkaline nitrite is treated with the diaminopyrimidine either in the form of a salt or with simultaneous addition of hydrochloric or acetic acid. The first phase of the reaction is usually carried out at 0°C, in some cases the reaction being terminated by heating to 50-60°C. With diaminopyrimidines which are sparingly soluble in water, the reaction was carried out in an organic solvent using amylnitrite. Excess nitrous acid can possibly attack the amino groups present. This was employed in some cases for the preparation of the hydroxy derivatives. ... 

One of the important mechanisms by which orally administered steroids are inactivated involves the formation of water-soluble derivatives at the 17 position, a process that is greatly reduced in 17a-alkyl-17(3-hydroxy derivatives. Extensive use of the resulting orally active compounds has since revealed that 17 alkylation also leads to increased liver toxicity. Preparation of the first of these compounds, nor-methandrolone (32-3), starts by addition of methylmagnesium iodide to estrone methyl ether (9-1) to give the 17a methyl derivative. Birch reduction followed by acid hydrolysis leads to normethandrolone (32-3) [16]. 

Boron-functionalized metallacarboranes might also serve as precursors to more complex organometallic systems such as the trigonally symmetrical 28 (Scheme 7). In a recent development,12 we have found a route to water-soluble B-hydroxy derivatives 30. 

The important property of these compounds is that they will couple with aromatic amines and hydroxy derivatives to form highly coloured products which, when rendered soluble by sulphonation, give rise to a great range of dyestuffs known as the azo dyes. A simple example of a coupling reaction is shown in the following equations ... 

Altogether, the stability of halogenated fuUerenes increases with the halogen content, and it decreases in the series F > Cl > Br 1. Successive reactions of the halofuUerenes are limited, among others, by their in parts extremely low solubility in organic solvents. StiU they tend to hydrolyze and react even with atmospheric humidity to give hydroxy derivatives or epoxides. 

Glycolic acid is an alpha-hydroxy acid, soluble in alcohol, derived from fruit and milk sugars. It can be produced with ethylene glycol-oxidizing microorganisms such as Pichia naganishii AKU 4267 and Rhodotorula sp. 3 Pr-126. Under optimized conditions, they form... 

Further, it is found that B-OMe-9-BBN is for more powerful than any other species examined (Table 25.13). Another advantage of this reagent is its easy removal from the product. B-Methoxy-9-BBN forms the hydroxy derivative, which is soluble in sodium hydroxide as the ate complex. Consequently, it provides a practical method for the reduction of esters in the presence of reducible groups such as chloro and nitro (Table 25.13) [39]. 

These compounds are isomeric with the saccharides, since they have the general formula C, (H20) they are, however, chemically distinct from the sugars, being hydroxy derivatives of benzene in which there is no potential aldehyde or ketone group. On account of their hydroxylation, cycloses are very soluble in water and have a sweet taste. As a class they are stable, non-reducing compounds, and do not give the general tests for carbohydrates. Seven cycloses are known to exist. 

Hsematoporphyrin, C3 H,gOgN4, an iron-free derivative of h m, is obtained by the action of strong acids on haemoglobin, or by dissolving haematin chloride in glacial acetic acid saturated with HBr. After four days, the mixture is diluted and the porphyrin precipitated by exact neutralisation. Haematoporphyrin is a dark violet powder, almost insoluble in water, but soluble in alcohol, alkalies, and concentrated sulphuric acid. It is a di-hydroxy derivative of Protoporphyrin, in which each vinyl side-chain, —CH CHg, has become —CHg.CHg.OH. 

N-Benzylamides are recommended when the corresponding acid is liquid and/or water-soluble so that it cannot itself serve as a derivative. Phe benzylamides derived from the simple fatty acids or their esters are not altogether satisfactory (see Table below) those derived from most hydroxy-acids and from poly basic acids or their esters are formed in good yield and are easily purified. The esters of aromatic acids yield satisfactory derivatives but the method must compete with the equally simple process of hydrolysis and precipitation of the free acid, an obvious derivative when the acid is a solid. The procedure fails with esters of keto, sul phonic, inorganic and some halogenated aliphatic esters. 

In general, benzoylation of aromatic amines finds less application than acetylation in preparative work, but the process is often employed for the identification and characterisation of aromatic amines (and also of hydroxy compounds). Benzoyl chloride (Section IV, 185) is the reagent commonly used. This reagent is so slowly hydrolysed by water that benzoylation can be carried out in an aqueous medium. In the Schotten-Baumann method of benzoylation the amino compound or its salt is dissolved or suspended in a slight excess of 8-15 per cent, sodium hydroxide solution, a small excess (about 10-15 per cent, more than the theoretical quantity) of benzoyl chloride is then added and the mixture vigorously shaken in a stoppered vessel (or else the mixture is stirred mechanically). Benzoylation proceeds smoothly and the sparingly soluble benzoyl derivative usually separates as a solid. The sodium hydroxide hydrolyses the excess of benzoyl chloride, yielding sodium benzoate and sodium chloride, which remain in solution ... 

Amino-4-nitrophenol. This derivative, 2-hydroxy-5-nitroani1ine (9), forms orange prisms from water. These prisms are hydrated with one water of crystallization, mp 80—90°C, and can be dehydrated over sulfuric acid to the anhydrous form, mp 143 —145°C. The compound is soluble in ethanol, diethyl ether, acetic acid, and warm benzene and slightly soluble in water. 

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). 

This mixture is known as Quinoline Yellow A [8003-22-3] (Cl 47000) and is most widely used with polyester fibers (109). Upon sulfonation, the water-soluble Quinoline Yellow S or Acid Yellow 3 [8004-92-0] (Cl 47005) is obtained. This dye is used with wool and its aluminum salt as a pigment. Foron Yellow SE-3GL (Cl Disperse Yellow 64) is the 3-hydroxy-4-bromo derivative. Several other quinoline dyes are commercially available and find apphcations as biological stains and analytical reagents (110). 

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