Toluenesulphonic acid

Sulphonic acids are frequently crystalline solids, readily soluble in water and often hygroscopic. Because of the difficulty of isolation of the free acids, they are usually encountered as the alkali metal salts. 

Extract the acidified solution with ether, remove the ether and identify the phenol in the usual manner (see Section IV,114).f Add a few drops of bromine water or nitric acid to the aqueous layer and test for sulphate with barium chloride solution. 

Once the presence of a sulphonate group has been established (and, if possible, the phenol isolated), the compound may be characterised by the preparation of a derivative. It must be remembered that both sulphoxides RSOR and sulploones RS02R yield sulphur dioxide on fusion with caustic alkali and acidification. 

Sulphonamides. Mix together 1-0 g. of the dry acid or 1-2 g. of the anhydrous salt with 2-5 g. of phosphorus pentachloride and heat under a reflux condenser in an oil bath at 150° for 30 minutes. Cool the mixture, add 20 ml. of dry benzene, warm on a steam bath and stir the solid mass well to extract the sulphonyl chloride filter. Add the benzene solution slowly and with stirring to 10 ml. of concentrated ammonia solution. If the sulphonamide precipitates, separate it by filtration if no solid is obtained, evaporate the benzene on a steam bath. Wash the sulphonamide with a little cold water, and recrystallise from water, aqueous ethanol or ethanol to constant m.p. 

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 clilorosulphonanilide 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. 

Preparation of p-Toluenesulphonic Acid (SECTION 476).— To 25 grams of toluene in a 200-cc. flask add 25 cc. of pure concentrated sulphuric acid, and place on the steam-bath. Allow the mixture to stand until the toluene has dissolved. This will require about 2 hours if the flask is shaken once in a while. Let the solution cool before it solidifies pour it, with stirring, into 100 cc, of pure concentrated hydrochloric acid. Heat the mix- 

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C7H7CIO1S, p-CHjCjsH SOjCI. Colourless crystals, m.p. 7l°C, formed by the action of chlorosulphonic acid on toluene. Esters of toluenesulphonic acid are frequently called tosylatesand their formation tosylation. Many tosylates are easily obtained crystalline, and the reaction is thus of considerable importance. 

The sulphuric acid may be replaced by 1-2 g. of sulphamic acid (NH,SOjH) or by p-toluenesulphonic acid (p-CHjCjH SOjH). 

The melting points of a number of sulphonacetamides are —benzene-sulphonic acid, 125° p-toluenesulphonic acid, 137° p-bromobenzene-sulphonic acid, 203° m-nitrobenzenesulphonic acid, 189° p-nitroben-zenesulphonic acid, 192° naphthalene-a-sulphonic acid, 185° and naphthalene-p-sulphonic acid, 146°. 

Esters of /i-toluenesulphonic acid, which are of great value as alkylating agents, may be prepared by interaction of p-toluenesulphonyl chloride and the alcdiol in the presence of sodium hydroxide solution or of pyridine, for example ... 

Supplement (combined with Volume XII) XI, 2nd 1933 1605-1739 2. Sulphonic acids Benzenesulphonic acid, 26. p-Toluenesulphonic acid, 97. Naphthalene - sulphonic acid, 155. Hydroxy-Sulphonic acids Phenol-sulphonic acid, 234. Naphthol-sulphonic... 

The striking effect of the catalyst is exemplified by the reaction of pregna-4, 16-diene-3,20-dione (10) with benzyl mercaptan. In the presence of piperidine only conjugate addition occurs to give (11) whereas with pyridine hydrochloride only the 3-benzyl thioenol ether (12) is formed. In the presence of p-toluenesulphonic acid both reactions take place to yield (13). 

A ( )-Enol-l 1-acetates are formed by distillation of acetic anhydride in the presence of / -toluenesulphonic acid. Another procedure employed for the synthesis of enol benzoates involves treatment with benzoic anhydride and triphenyl methyl sodium or ethynyl sodium. Suitable procedures utilizing a diluent have been developed for the enol esterification of a 20-ketone without affecting an 11-ketone. 

Further mechanistic evidence was provided by Benkeser and Krysiak658, who determined the effects of added salts and water on the rates of cleavage of xylyltrimethylsilanes by p-toluenesulphonic acid in acetic acid at 25 °C, the progress of the reaction being followed by dilatometry the first-order rate coefficients are given in Table 227. Clearly the addition of water retards the reaction, as... 

Eichler and Wahl have attempted an isotopic study ( Os and Os) of the exchange reaction between Os(dipy)3 and Os(dipy)3 using a direct injection technique so that reaction times 7 x 10 sec were possible. With total osmium 10" M in aqueous sulphate media at 0 °C complete exchange was observed. The separation methods used were, (a) perchlorate precipitation (in presence of iron(II) carrier) and (6) extraction with p-toluenesulphonic acid in nitromethane, of the osmium(II) complex. A lower limit of 1 x 10 l.mole. sec was placed on the rate coefficient (0 °C, 3.0 M H2SO4). Dietrich and Wahl using the line broadening effect produced by Os(dipy)3 on the nmr spectrum of Os(dipy)3 have been able to propose a value of > 5x 10" l.mole . sec at 6 °C in D2O (0.14 M [Cr] and 5x10 M [D- ]). 

Fig. 4.1. Potential ranges of solvents, (a) h.n.p.s of acids. I, Acetic acid II, benzoic acid III, formic acid IV, salicylic acid V, sulphuric acid VI, p-toluenesulphonic acid, (b) h.n.p.s of conjugate acids of I, n-butylamine II, piperidine III, ethylenediamine (1) IV, ammonia V, ethylenediamine (2) VI, pyridine.

With a weak acid such as hydrochloric and p-toluenesulphonic acids, [H+X ] and [H+] are negligibly small compared with [HX], so that eqn. 4.66 becomes Chx = [HX] also as in acid solution [S ] from autoprotolysis of the solvent H2S can be neglected, the electroneutrality rule reduces to... 

The authors studied, as they call it, "acid-base equilibria in glacial acetic acid however, as they worked at various ratios of indicator-base concentration to HX or B concentration, we are in fact concerned with titration data. In this connection one should realize also that in solvents with low e the apparent strength of a Bronsted acid varies with the reference base used, and vice versa. Nevertheless, in HOAc the ionization constant predominates to such an extent that overall the picture of ionization vs. dissociation remains similar irrespective of the choice of reference see the data for I and B (Py) already given, and also those for HX, which the authors obtained at 25° C with I = p-naphthol-benzein (PNB) and /f B < 0.0042, i.e., for hydrochloric acid K C1 = 1.3 102, jjrfflci 3 9. IQ-6 an jjHC1 2.8 10 9 and for p-toluenesulphonic acid Kfm° = 3 7.102( K ms 4 0.10-6) Kmt = 7 3.10-9... 

Acid titrants are commonly perchloric acid and sometimes hydrochloric, benzenesulphonic or p-toluenesulphonic acid. 

Ethyl acetate is an oxygenated solvent widely used in the inks, pharmaceuticals and fragrance sectors. The current global capacity for ethyl acetate is 1.2 million tonnes per annum. BP Chemicals is the world s largest producer of ethyl acetate. Conventional methods for the production of ethyl acetate are either via the liquid phase esterification of acetic acid and ethanol or by the coupling of acetaldehyde also known as the Tischenko reaction. Both of these processes require environmentally unfriendly catalysts (e.g. p-toluenesulphonic acid for the esterification and metal chlorides and strong bases for the Tischenko route). In 1997 BP Chemicals disclosed a new route to produce ethyl acetate directly from the reaction of ethylene with acetic acid using supported heteropoly acids... 

Eight grams of the crude ester, which had been prepared from tosyl azide and sodium butoxide, then stored for four weeks at 0°C, was to be distilled at 0.2 mm Hg. On the bath reaching 70°C, there was a violent explosion. This was attributed to a toluenesulphonic acid autocatalysed elimination. However, presence of butyl azide as an impurity seems probable. 

Chromium-mediated oxidation of benzylic methylene groups to the corresponding oxo derivatives has also been reported [4], Tri-n-butylstannyl chromate appears to be the best co-oxidant and a trace of 4-toluenesulphonic acid also aids the oxidation. 

Hydrolysis of the diethylacetal function employing p-toluenesulphonic acid in acetone, pyridinium p-toluene-sulphonate in EtOH, and a suspension of Si02 in hexane. In all cases the corresponding aldehyde is obtained in high yield as a Z E isomeric mixture. Transmetallation of acetal with Me2Cu(CN)Li2 followed by treatment with c-hexenones giving the 1,4-addition product. Alternatively, transmetallation with n-BuLi and reaction with benzaldehyde giving the expected alcohol. 

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