Chlorosulphonation aromatic

A further difference between aliphatic and aromatic hydrocarbons is that only the latter are capable of direct sulphonation. Thus benzene when heated with concentrated sulphuric acid gives benzenesulphonic acid, a reaction which proceeds more readily, however, if chlorosulphonic acid is used instead of sulphuric acid an excess of chlorosulphonic acid however may convert the sul phonic acid into the sulphonyl chloride (c/. p. 181). 

Sulphonamides of aryl ethers. Aromatic ethers react smoothly in chloroform solution with chlorosulphonic acid at 0° to give suljihonyl chlorides, for example ... 

The chemical resistance of PCTFE is good but not as good as that of PTFE. Under certain circumstances substances such as chlorosulphonic acid, molten caustic alkalis and molten alkali metal will adversely affect the material. Alcohols, acids, phenols and aliphatic hydrocarbons have little effect but certain aromatic hydrocarbons, esters, halogenated hydrocarbons and ethers may cause swelling at elevated temperatures. 

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. 

Alternatively, impurities can sometimes be removed by conversion to derivatives under conditions where the major component does not react. For example, normal (straight-chain) paraffins can be freed from unsaturated and branched-chain components by taking advantage of the greater reactivity of the latter with chlorosulphonic acid or bromine. Similarly, the preferential nitration of aromatic hydrocarbons can be used to remove e.g. benzene or toluene from cyclohexane by shaking for some hours with a mixture of concentrated nitric acid (25%), sulphuric acid (58%), and water (17%). 

From its general behaviour it is clear that chlorosulphonic acid is closely related to sulphuric acid. Like the latter acid, but with more vigour, it attacks aromatic hydrocarbons with formation of organic sidphonic acids of the structure R.SOa.OH and sulphones of the structure Rx... 

The arylsulphonyl chlorides may be obtained more conveniently from the aromatic hydrocarbon by reaction with an excess of chlorosulphonic acid (chlorosulphonation)... 

Aromatic hydrocarbons react with chlorosulphonic acid to yield the corresponding sulphonyl chlorides (the process is known as chlorosulphonatiori). These do not usually crystallise well and are therefore converted into the sulphona-mides by treatment with concentated ammonia solution or with solid ammonium carbonate. (See also Section 6.4.2, p. 877.)... 

PAS-FTIR spectra have been used to find out the interaction of chlorosulphonated polyethylene (CSM) and carbon black N110 [48]. A number of bands in the 1800 cm1-1680 cm1 region in the spectrum of Nil0 (Figure 2.7) confirm the presence of different carbonyl functionalities, which may include carboxyl group, lactone and quinone. The band at 1651 cm1 is characteristic of aromatic double bonds in the carbon black. The... 

Relatively high solubility of PBLG in many solvents can be explained by the interaction of flexible side groups with solvents. On the other hand, for aromatic polyamides with p-structure, e.g. PPTA, the solubility is observed only for a very narrow range of solvents, mostly for concentrated acids (sulphuric, phosphoric, chlorosulphonic, hydrofluoric, and other acids). In this case the interaction of acid molecules with amide groups of a polymer reaches the energy of chemical reactions. 

Chlorosulphonic acid, and other derivatives of sulphuric acid, may also be used for the formation of sulphonic acids by sulphonation of aromatic compounds. These sulphonating reagents are more reactive than sulphuric acid itself78,84 and so milder conditions (temperatures of 0-25 °C are typical) may be used with them. In addition, water is not normally involved in the reaction and the separation problems, caused by the use of excess reagents, as is the case with sulphuric acid, are significantly reduced. 

Sulphonation of aromatic compounds with chlorosulphonic acid proceeds in excellent yields (usually > 75%) if inert solvents are used85 - 94 In this case the use of an inert solvent... 

Dehydroabietic acid can undago typical aromatic substitution reactions (e.g. acylation, chlorosulphonation, sulphon-ation and nitration) with prefoential functionalization of the more reactive 12 position, followed in some cases by the 14 position. These reactions were first exploited in the 1930s-1940s [5, 12-14]. The nitration of dehydroabietic acid (Fig. 4.6) was one of the first reactions studied because of the synthetic vCTsatility of the nitro group, namely as precursor of amino groups [14]. More recently, this reaction has been optimized using less harsh conditions [15,16]. 

A study of the reaction of chlorosulphonic acid with aromatics has appeared. The first step is a sulphonation, followed by conversion of the sulphonic acid into a sulphonyl chloride. 

Tables 58 and 59 contain information about detection. The most popular reagents have been aromatic aldehydes-acids (Nos. 11, 48, 133, 219, 260, 262), chlorosulphonic acid-acetic acid (Rgt. No. 45), sulphuric acid (No. 241) and antimony (III)-chloride (No. 15).

Carbanions of alkyl-p-tolylsulphones react with carbon tetrachloride giving a-chlorosulphones, which may be hydrolysed to ketones/ Aromatic ketones can therefore be prepared from benzylic p-tolylsulphones (Scheme 10). 

In the heterocyclic field, sulphur substitutions include the sulphonation of quinoline to produce mainly the 8-acid, plus the 5-, 6-, and 7-acids, the chlorosulphonation of 2-(3,4-dicholorophenyl)- and 2-(3-pyridyl)-imidazole (on the imidazole ring) and of 2-(4-chlorophenyl)imidazole on both aromatic rings, the tosylation at N-3 of some 2-(monosubstituted amino)-l,3,4-thiadiazoles (which isomerise to products that are sulphonylated on the exocyclic nitrogen), and the thiolation of 2-methylindolizine with diaryl disulphides to form (53). ... 

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