Toluene sulphonic acids

The sulphonation of toluene at 100-120° results in the formation of p-toluene-sulphonic acid as the chief product, accompanied by small amounts of the ortho and meta isomers these are easily removed by crystallisation in the presence of sodium chloride. Sulphonation of naphthalene at about 160° 3uelds largely the p-sulphonic acid at lower temperatures (0-60°) the a-siil-phonic acid is produced almost exclusively. 

A number of basic materials such as hydroxides, hydrides and amides of alkaline and alkaline earth metals and metal oxides such as zinc oxide and antimony oxide are useful catalysts for the reaction. Acid ester-exchange catalysts such as boric acid, p-toluene sulphonic acid and zinc chloride are less... 

Toluene-2,6-di isocyanate p-Toluene sulphonic acid o-Toluidine... 

The effect of the catalyst-steroid ratio has been studied for the p-toluene-sulphonic acid-catalyzed ketalization of androst-4-ene-3,17-dione. Selective formation of the 3-monoketal is observed with the use of an equimolar amount of ethylene glycol and a low ratio of catalyst to steroid. ... 

Oxidation of malonic acid by Cr(VI) has been noted briefly by Snethlage and later by Kemp and Waters . The kinetics are simple second-order but the acidity dependence is complex. Heckner et a/. find the alkaline permanganate oxidation of malonic acid (and also of o- and p-toluic acids and of p-toluene-sulphonic acid) to be retarded by added Mn(VI), viz. 

The availability of Nafion on silica has not only lowered the cost of the resin but also has made it versatile (Sun et al., 1997 Harmer et al., 1998). A number of industrially important reactions have been attempted, with considerable success, with these catalysts. Consider the Fries rearrangement of phenyl acetate to p-acetyl phenol (/t-hydroxy acetophenone). This has been accomplished by Hoelderich and co-workers (Heidekum, 1998). In the ca.se of alkylation of benzene with benzyl alcohol, Amberlyst-15 and p-toluene sulphonic acid are ineffective and Nafion on silica works well at 80 °C. 

Gonzalez and Holt (1981) have shown how macrocyclic lactones can be made conveniently in microemulsion media. Thus, intramolecular e.sterification of (o-hydroxy alkanoic acids can be carried out with a very small amount of acid catalysts like p-toluene sulphonic acid, and rates are markedly higher as compared to simple media. 

A trade-off between selectivity and solvability should be considered when selecting a solvent. Adding co-solvents can make tough separations technically and economically feasible. Lee and Gentry (1997) have tabulated dielectric constants of selected solvents. A new class of solvents is based on the use of an aqueous. solution of hydrotropes. Gaikar and Sharma (1989) have reported the separation of close-boiling p-cresol and 2,6-xylenol with aqueous solutions of hydrotropes, such as the sodium salt of p-toluene sulphonic acid, as a novel solvent in extractive distillation. 

Polymeric adsorbents have also been found to be very useful, and even highly water-loving undesired materials like p-toluene sulphonic acid from waste streams can be recovered via ad.sorption and regeneration with solvents like fv -propanol. In such instances, the regeneration of activated carbons is not satisfactory, even with aqueous sodium hydroxide. Solutes like phenols, substituted phenols, aromatic amines, heterocyclic amines (pyridine, picolines, etc.) can be recovered, in a rewarding way, from aqueous solutions. 

From a preparative aspect, Peck et alX have employed the counter-current distribution technique with a partition system of water/ butanol/p-toluene sulphonic acid to separate and purify the neamine (neomycin A) present in commercial neomycin. 

The water formed in the reaction is continuously removed from the reaction mixture by azeotropic distillation, in order to avoid reversible reaction between water and ester. The progress of reaction can be followed either by measuring the amount of water or by determining the amount of unreacted acid in aliquots withdrawn at regular intervals of time. The reaction can be carried out either in presence of a catalyst, i.e. a weak acid like p-toluene sulphonic acid (a strong acid can hydrolyse the polymer, formed) or in absence of the catalyst. 

Barker et al. have demonstrated a vigorous benzyloxy-group participation for the ethanolysis of 4-0-benzyl-1-0-toluene-p-sulphonyl-pentane-l,4-diol to give 2-methyltetrahydrofuran, benzyl ethyl ether, and toluene- -sulphonic acid. Cyclization to 1,4-anhydropentitol deriv-... 

A reaction which is analogous to the orthoester synthesis but which utilises glycosyl oxazolines affords means of synthesising, 2-trans-2 amino-2-deoxy-glycoside derivatives. Treatment of the gluco compomd (17) with phenol in the presence of toluene- -sulphonic acid thus gave the glycoside (18), and it was also utilised in a nucleoside synthesis 48). 

In similar fashion a diaminodisaccharide derivative( 7P) has been prepared from the appropriate oxazoline and 6-ol in nitromethane using toluene- -sulphonic acid as catalyst 49). 

Aryl glycosides of 2-amino-2-deoxy sugars, as might be expected, can be prepared by similar techniques as was illustrated by the synthesis of phenyl 3,4,6-tri-0-acetyl-2-acetamido-2-deoxy-p-D-glucoside and -D-galactoside by toluene -sulphonic acid catalysed reactions between phenol and the hexosamine penta-acetates These products were then anomerised using zinc chloride as catalyst to provide means of obtaining -anomers. 

Since this whole sequence is reversible, it will go forwards in ethanol and backwards in water. What do you think would happen if acetaldehyde and n-butanol were dissolved together in a 1 3 molar ratio, and the solution refluxed for twelve hours with a catalytic quantity of toluene sulphonic acid, and the product dried and distilled ... 

CH3CH(OBu-n)2 - Acetaldehyde is the carbonyl component, butanol the nucleophile, and toluene sulphonic acid is the catalyst. How would you hydrolyse PhCH(OEt)a, and what would you get ... 

Catalyst Ion exchanger with DVB content (%) p-toluene- sulphonic acid... 

M. R. Jenner and R. Khan, Use of dimethoxydiphenylsilane, AI,AI-dimethylfonnamide, and toluene-p-toluene sulphonic acid as a novel acetalating reagent, J. Chem. Soc. Chem. Common. 30 (1980). 

Some sulphonic acids, e.g., benzene and toluene sulphonic acids, may be formed at ordinary temperatures, while others require a considerably higher temperature. In some cases 100% H2S04 (monohydrate—-S03.H20) is necessary. The influence of temperature (see table below), concentration of acid, time of reaction, and the presence of other substituents is very marked, and different isomers are formed under different conditions. 

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