Preparation of the sodium salt

Detailed directions for the preparation of the sodium salt are given by Smith. Sommer also made many qualitative observations on the properties of other salts and of the acid itself and its oxidation product, a disulfide. These observations were put on a firmer base by the extensive investigations of Browne et (see also references 50 and 51). 

When chlorine reacted with sodium diethyl dithiophosphate in the presence of an organic solvent, the desired compound was obtained in good yield. The reaction of phosphorus pentachloride on the sodium salt resulted in the same product. Thiophos-phoryl chloride is a probable by-product of this reaction. It was later found that diethyl dithiophosphoric acid could be chlorinated in an organic solvent without the intermediate preparation of the sodium salt. 

Preparation of the sodium salt of ethyl arsenic acid ... 

The exact amount of copper powder used as a catalyst in the preparation of the sodium salt of aniline is not important. Approximately 0.2 g. has been found to be satisfactory in runs of the size described. 

Owing to the tendency of the acid to hydrolyse, the preparation of the sodium salt is a delicate operation. The neutralisation of the acid with sodium hydroxide is therefore undertaken under intensive cooling and the salt solution is evaporated under vacuum. Maylott and Meyer (1964) recommended anhydrous reaction conditions for the formation of the salt. The reacting anhydrous acid and dry alkali compound are dispersed in liquid hydrocarbon. At the end of the reaction the sodium salt is filtered off from the reaction medium. 

Preparation of diethyl ester of allyl-(l -methyl butyl) malonate (//) Condensation of (/) above with urea and Hi) Preparation of the sodium salt. 

Alternative dry methods of preparation of the sodium salt are to heat solid sodium pyrophosphate with ammonium chloride (5.183), disodium phosphate with ammonium nitrate (5.164), or P40,o with sodium carbonate under anhydrous conditions (4.59). 

Unless all the excess of ammonia has been driven off in the preparation of the neutral salt, the result obtained on adding ferric chloride will be misleading owing to the precipitation of ferric hydroxide. If this is suspected, the tests should be repeated using an aqueous solution of the pure sodium salts of these acids for comparison. 

The above simple experiments illustrate the more important properties of aliphatic acid chlorides. For characterisation, the general procedure is to hydrolyse the acid chloride by warming with dilute alkali solution, neutralise the resulting solution with dilute hydrochloric acid (phenol-phthalein), and evaporate to dryness on a water bath. The mixture of the sodium salt of the acid and sodium chloride thus obtained may be employed for the preparation of solid esters as detailed under Aliphatic Acids, Section 111,85. The anilide or p-toluidide may be prepared directly from the acid chloride (see (iii) above and Section III,85,i). 

To prepare the free sulphinic acid, dissolve some of the sodium salt in cold water and cautiously acidify with hydrochloric acid avoid an excess of mineral acid since it dissolves the sulphinic acid to a certain extent. The resulting p-tolueneaulphinic acid is difflcult to dry without partial conversion into the sulphonic acid and thiolsulphonic ester... 

Kolbe-Schmitt reaction (Section 24 10) The high pressure re action of the sodium salt of a phenol with carbon dioxide to give an o hydroxybenzoic acid The Kolbe-Schmitt reac tion IS used to prepare salicylic acid in the synthesis of as pinn... 

Low molecular weight poly(l,3-phenylene oxide) [25190-64-1] has been prepared from the sodium salt of y -chlorophenol with copper as a catalyst... 

R)-Calcium pantothenate (3) is prepared by condensing (R)-pantolactone (9) with P-alanine (10) in the presence of base, followed by treatment of the sodium salt (11) with calcium hydroxide. 

This reaction was also extended to other aromatic aldehydes for the preparation of a,P unsaturated carboxyUc acids. Several mechanisms of the reaction have been proposed (45). The most accepted mechanism iavolves the reaction of the aldehyde with the enol form of the acid anhydride which is promoted by the presence of the sodium salt or of another base. The resulting reaction product is then dehydrated iato an unsaturated carboxyUc acid. 

For the most part, thiacyanocarbons are derived from "BAhr s Salt" [18820-77-4] (10), prepared from carbon disulfide and sodium cyanide (61) through the intermediacy of the sodium salt of carbonocyanidodithione acid [33498-03-2] C2NS2Na. 

Pentobarbital (5-ethyl-5-r-methylbutyl barbituric acid. Nembutal) [76-74-4] M 226.4, m 127 (dec), pKEst(i) 8.0, pKEst(2) 12.7. Soln of the sodium salt in 10% HCl was prepared and the acid was extracted by addition of ether. Then purified by repeated crystn from CHCI3. [Bucket and Sandorfy J Phys Chem 88 3274 1984.]... 

Pilocarpine dissolves in dilute soda solution, and the rotation is thereby reduced, due to the formation of the sodium salt of pilocarpic acid, CiiHigOgNa, of which pilocarpine is the lactone. Amorphous barium and copper salts have been prepared. Pilocarpine in dilute sulphuric acid gives with hydrogen peroxide, followed by potassium dichromate, a bluish-violet colour soluble in benzene. For the identification of the alkaloid Wagenaar recommends precipitation with gold chloride solution. 

Tribenzenesulfenamide (PhS)3N is obtained as a pale yellow solid by the treatment of the sodium salt of dibenzenesulfenamide, generated in situ, with acetic anhydride (Eq. 10.15). The perfluorinated analogue (C6F5S)3N is prepared by the reaction of (C6F5S)2NH and CeFsSCl in diethyl ether. 

The free acid, l,2,3,4-thiatriazole-5-thiol, may be prepared from hydrogen azide and carbon disulfide, but the simplest way to obtain the acid is to treat a chilled solution of the sodium salt with concen-... 

Reduction of the exocyclic double bond generally decreases neuroleptic activity in this series. Some of these compounds, however, show other activities. Methixene (44), for example, is used as an antispasmodic agent. It is prepared by alkylation of the sodium salt of thioxanthene (43) with w-methyl-3-chloromethyl-piperidine. ... 

Azelastine (107) is an antiallergic/antiasthmatic agent prepared from 4-chlorobenzyl-2 -car-boxyphenylketCHie (105) by condensation with hydrazine to give the phthalazinone (106) followed by reaction of the sodium salt of this last with 2-(2-chloroethyl)-N-methylpyrrolidine (presumably involving nucleophilic ring expansion of the bicyclic quaternary salt putatively formed as a first product) to complete the synthesis [30]. 

Thus, a series of bis-cyclopentadienetitanium(III) dithiocarbamate and xanthate complexes have been prepared by Coutts et al. (49-51) by reaction of the sodium salts of the ligands with [Cp TiJCl (Cp =7r-cyclo-pentadiene) in air-free water under an inert atmosphere the dithiocarbamate complexes are bright-green, and the xanthates are blue. 

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