Sulphur trioxide, sulphonation

While the saturated hydrocarbons are but slowly affected by sulphuric acid or sulphur trioxide, their derivatives react more energetically with these reagents. When alcohol, for example, is treated with sulphur trioxide, sulphonation takes place, that is, the alcohol is converted into a sulphonic acid —... 

Sulphur dioxide Sulphur trioxide Sulphonic acids Sulphones... 

Johnson, G. and Crynes, B. L. Modelling of a thin film sulphur trioxide sulphonation reactor. Ind. Eng. 

The sulphonic acids are usually prepared by the action of sulphuric acid upon a compound. The concentration of the acid and the temperature of reaction are varied according to the reactivity of the compound. Often oleum is used or even chiorosulphonic acid. Alternatively sulphur trioxide complexed to pyridine or dioxan can be used with reactive substrates. Aminosulphonic acids such as sulphanilic and naphthionic acids are most conveniently prepared by heating the sulphate of the amine at ISO C. 

Sulphur trioxide is used on an industrial scale for sulphonating organic compounds. 

Sulphur oxides G Sulphur dioxide Sulphur trioxide Coal distillation Combustion of coal and heavy fuel oil Detergents (sulphonation of alkyl benzenes) Electricity generation... 

Most research workers have employed an aqueous sulphuric acid solution of the aromatic, but a few have used other solvent systems and sulphonating agents. Principal among these are Hinshelwood et a/.139, who measured the rates of sulphonation of aromatics by sulphur trioxide in nitrobenzene at temperatures between 0 and 100 °C, a minimum of about 40 °C being employed for each compound. The initial reaction rate was given by... 

The first kinetic study appears to have been that of Martinsen148, who found that the sulphonation of 4-nitrotoluene in 99.4-100.54 wt. % sulphuric acid was first-order in aromatic and apparently zeroth-order in sulphur trioxide, the rate being very susceptible to the water concentration. By contrast, Ioffe149 considered the reaction to be first-order in both aromatic and sulphur trioxide, but the experimental data of both workers was inconclusive. The first-order dependence upon aromatic concentration was confirmed by Pinnow150, who determined the equilibrium concentrations of quinol and quinolsulphonic acid after reacting mixtures of these with 40-70 wt. % sulphuric acid at temperatures between 50 and 100 °C the first-order rate coefficients for sulphonation and desulphonation are given in Tables 34 and 35. The logarithms of the rate coefficients for sulphonation... 

Brand et al.15B made extensive measurements of the rates of sulphonation of a range of unreactive aromatics by oleum containing up to 41 % of sulphur trioxide at temperatures between 0 and 45 °C, and found the reaction to be first-order in aromatic. First-order rate coefficients at 25 °C are given in Table 37, some of the... 

In this work, Brand and Horning158 showed that the rate of sulphonation of phenyltrimethylammonium ion was linearly related to the calculated concentration of protonated sulphur trioxide HSO3, indicating it to be the electrophile. Added sulphate anions reduced the rate for 4-nitrotoluene in direct proportion to their concentration, and this followed from the equilibrium... 

The lamp method involves combustion of a sample of sulphone in a closed system with an atmosphere of 30% oxygen and 70% carbon dioxide214. The mixture of sulphur dioxide and sulphur trioxide formed is converted in situ to sulphate by oxidation with hydrogen... 

The situation that was described in the previous accident happened again and even twice, with o-nitrotoluene and p-nitrotoluene during their sulphonation. Oleum containing 24% sulphur trioxide had been added to o-nitrotoiuene at 32 C. The reaction went out of control and caused the 2 I reactor to break and a very large volume of carbonised compound to be ejected (this was probably due to the decomposition of the sulphonic acid formed) ... 

Under more forcing conditions, such as the use of higher operating temperatures or of oleum (sulphur trioxide dissolved in anhydrous sulphuric acid), more than one sulphonic acid group can be introduced. This approach can lead to mixtures of isomers and, in practice, the reaction conditions must be carefully controlled if the desired isomer is to be produced in maximum yield. 

H acid (4.2) is possibly the most important single naphthalene-based intermediate. The preparation of this intermediate starts with a high-temperature sulphonation of naphthalene using 65% oleum (anhydrous sulphuric acid in which 65% by mass of sulphur trioxide has been dissolved) to give mainly naphthalene-1,3,6-trisulphonic acid, the nitration product from which is purified by selective isolation. Reduction of the nitro group followed by hydrolysis of the 1-sulphonic acid substituent by heating with sodium hydroxide solution at 180 °C completes the process (Scheme 4.27). 

The copolymer produced in this way has been found to be insoluble and infusible but is still chemically reactive. On heating the polymer with a mixture of sulphur trioxide and sulphuric acid, the sulphonic acid group gets introduced into the aromatic rings. The resin so formed is known as a cation exchanger. 

Since N02 and S03H are substituents of the second order, a second substituent enters in the m-position. Oleum containing a high percentage of sulphur trioxide finally converts benzene into benzene tri-sulphonic acid. Chlorosulphonic acid condenses with aromatic hydrocarbons, giving aryl sulphochlorides. 

Sulphonation Pyrrole, furan and thiophene undergo sulphonation with the pyridine-sulphur trioxide complex (CsHsN+SOs ). 

Benzene reacts with fuming sulphuric acid at room temperature to give henzenesulphonic acid. Fuming sulphuric acid contains added sulphur trioxide (SO3). Sulphonation of benzene can also be carried out with concentrated H2SO4, but with slower speed. In both cases, SO3 acts as an electrophile. 

It has already been recorded (p. 142) that hydrogen chloride and sulphur trioxide react to produce chlorosulphonic acid. The alkali chlorides, on the other hand, form chloropyrosulphonates, e.g. C1S02.0. S02.0Na, which are crystalline solids, decomposed by water 2 the alkali fluorides, however, yield the corresponding fluorosulphonates, such as F.S03Na3 (see p. 86). Sodium nitrite produces a nitrosotri-sulphonate, NQ2(S03)3Na.2 Alkali chlorides may be converted to sulphates with evolution of chlorine by the action at 300° to 600° C. of a mixture of sulphur trioxide and air. No fusion occurs nor does the evolved gas contain any sulphur dioxide.4... 

Amidosulphonie Acid, NH2.SOsH, may be obtained by the action of sulphur trioxide on dry ammonia.2 When an aqueous solution of hydroxylamine hydrochloride is saturated with sulphur dioxide and afterwards evaporated, amidosulphonie acid is obtained.3 Potassium imidosulphonate, NH(S03K)2, and potassium nitrilosulphonate, N(SOaK)a, are both decomposed by hot water with formation of potassium amido-sulphonate 4... 

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