Baumann

In the Schotten-Baumann method of benzoylation, the hydroxyl- or amino-compound (or a salt of the latter) is dissolved or suspended in an excess of 10% aqueous sodium hydroxide solution, a small excess (about 10% more than the theoretical amount) of benzoyl chloride is then added and the mixture vigorously shaken. Benzoylation proceeds smoothly under these conditions, and the solid benzoyl compound, being insoluble in water, separates out. The sodium hydroxide then hydrolyses the excess of benzoyl chloride, giving sodium... 

Thus phenol when subjected to the Schotten Baumann reaction first dissolves in the sodium hydroxide to give sodium phenoxide, which then undergoes CgH COCl + NaOCgH, CgHaCOOCeHj XaCl... 

When these benzoyl compounds separate in the course of the Schotten-Baumann reaction, they frequently occlude traces of unchanged benzoyl chloride, which thus escapes hydrolysis by the alkali it is advantageous there fore to recrystallise the benzoyl compounds whenever possible from ethanol or methylated spirit, since these solvents will esterify the unchanged chloride and so remove the latter from the recrystallised material. 

The Schotten-Baumann reaction may also be carried out, using, for example, benzene sulphonyl chloride, CeH,SO,Cl (. e., the acid chloride of benzene sulphonic acid, C H5SOjOH) in place of benzoyl chloride, and similar deri a-tives are obtained. Thus when phenol is dissolved in an excess of 10% sodium hydroxide solution, and then shaken with a small excess of benzene sulphonyl... 

The acidic properties of sulphonamides and their mono-substitution derivatives are particularly well illustrated in the alkyl ubstitution compounds, which by reason of these properties can be prepared by two distinct methods. Thus mono- and di-ethylamine, when subjected to the Schotten-Baumann reaction using benzenesulphonyl chloride, gi e benzenesulphonethylamide, and bcnzenesulphondiethylamide respectively. These compounds can also... 

Although benzenesulphonyl chloride has for simplicity been used in the above discussion, tolucne-/>- sulphonyl chloride, CHaCeH SO Cl, is more frequently used in the laboratory, owing to its much lower cost, the latter being due in turn to the fact that toluene-p-sulphonyl chloride is a by-product in the commercial preparation of saccharin. Toluene-p sulphonyl chloride is a crystalline substance, of m.p. 68° the finely powdered chloride will, however, usually react readily with amines in the Schotten-Baumann reaction it does not react so readily with alcohols, but the reaction may be promoted considerably by first dissolving the chloride in some inert water-soluble solvent such as acetone. 

Give benzoyl and toluene-/>-sulphonyl derivatives (Schotten-Baumann reaction) (p. 243) also benzene-sulphonyl derivatives. 

B) Benzoyl derivatives. Most amino-acids can be benzoyl-ated when their solutions in 10% aqueous sodium hydroxide are shaken with a small excess of benzoyl chloride until a clear solution is obtained (Schotten-Baumann reaction, p. 243). Acidification of the solution then precipitates the benzoyl derivative and the excess of benzoic acid, and the mixture must be filtered off, washed with water, and recrystallised (usually from ethanol) to obtain the pure derivative. (M.ps., p. 555 )... 

The dibenzoyl derivatives can be prepared by the normal Schotten-Baumann method, using 10% aqueous sodium hydroxide and an excess of benzoyl chloride, but the m.ps. of the dibenzoyl derivatives are inconveniently high (p- ssO-... 

Examples of benzoylation under Schotten-Baumann conditions are —... 

Benzoyl derivatives. Both primary and secondary amines form benzoyl derivatives under the conditions of the Schotten-Baumann reaction (see Section IV,52 and preceding discussion). 

The Schotten - Baumann method of benzoylation with benzoyl chloride in the presence of aqueous sodium hydroxide may be used. Full details are given under Amines Section IV.lOO, 2. 

By the Schotten-Baumann reaction. Under the usual Schotten-Baumann conditions (compare discussion preceding Section IV,52, also Section IV,100,2and Section IV,114,2), esters are readily formed, forexample ... 

Bemoyl chloride may replace acetyl chloride as a class reagent it possesses the advantage that it is only very slowly decomposed by cold water and consequently may be employed for detecting alcohols even in aqueous solution. The reaction is usually carried out in aqueous solution containing sufficient caustic alkali to decompose any excess of benzoyl chloride into the water-soluble alkali benzoate (Schotten - Baumann reaction compare Section IV,52). The benzoyl esters formed are insoluble in water ... 

Pinacol-pinacolone rearrangement Prileschajew epoxidation reaction Reformataky reaction Reimer-Tiemanii reaction Rosenmund reduction Sandmeyer reaction Schiemaim reaction Schmidt reaction or rearrangement Schotten-Baumann reaction Skraup reaction Sommelet reaction. ... 

Esterification of acid chlorides (Schotten-Baumann reaction) ... 

---