Sulphone method

CgH,N,Cl -h zSnCl, + 4HCI = CeHjNH NH, HCl + zSnCI when treated with an acid solution of stannous chloride (e.g., a solution in hydrochloric acid) but the yields are not as high as those obtained by the above sulphonate method. 

Retinol Derivatives. The sulphone method forms the basis of three new synthetic routes to vitamin A (retinol 95), involving condensation of the /3-ionylidene-ethyl (Cis) phenyl sulphone (96) with the epoxide (97) " or the chloride (98) or condensation of the /8-ionyl phenyl sulphone (99) with the allylic chloride (100). Conditions have been developed under which the elimination of the sulphone group from the reaction intermediate (101) occurs efficiently. In another stereospecific... 

The synthon (117) is derived from the optically active C22-allenic apocarotenal 118 which is prepared via a Wittig condensation of the (3S)-Ci5-allenic aldehyde 103 with the Cy-phosphonium chloride 119. Reduction of the aldehyde group in 118 (a mixture of 11Z and 11 ) with NaBH4, followed by acetylation, yields the acetate 120, which is converted into the sulphone 117 by heating under reflux with sodium sulphinate in propan-2-ol and water. Condensation between the (all- )-allenic sulphone 117 and the formyl ester (5R,6S)-116 under the conditions of the sulphone method furnishes a mixture (ca. 1 1) of the optically active peridinin (108) and its (11 )-isomer and these are cleanly separated by preparative HPLC in the dark Scheme 27) [70,72]. 

In a similar manner and yield, resorcinol is produced from the 1,3-isomer although the greater reactivity of the product towards condensation with the acetone by-product is an added complication. The route is shown together with older sulphonation method. 

For different hydrocarbons, sulphonation methods are to a large extent of the same kind. Equally with other stages and techniques of surfactant production, the methods experience an impressive progress both in implementation and technological innovations from the sulphonation with sulphuric acid and related agents [61, 62] to the present-day SO3 sulphonation processes [59, 62-65]. 

Table 1. List of conjugated alkylidenebutenolides that have been synthesized by the sulphone method...

Condensation between the (all- ) allenic sulphone 51 and the formyl ester 45 under the conditions of the sulphone method furnishes a mixture (ca. 1 1) of the optically active peridinin (558) and its (1 l )-isomer and these are cleanly separated by preparative HPLC in the dark [17,21] (Scheme 10). 

Thesulphonatedpolyimidemembranesarebasedon4,4 -diaminobiphenyl-2,2 -disulphonic acid (BDSA), 4,4 -oxydianiline (ODA), 4,4 -oxydiphthalic anhydride (ODPA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA). The study of the surface properties of fluorinated polyimides exposed to vacuum ultraviolet (VUV) radiation and atomic oxygen may help us understand the stability of these polymers. It will also be interesting to apply this sulphonation method to some novel high molar mass poly-etherimide, as reported by Hsio and Yang (1997). 

Aromatic nitriles (or aryl cyanides) can be obtained by methods (1) and (3). but not by method (2). In addition, aromatic nitriles can be prepared by two other methods, (a) from the corresponding diazo compound by Sandmeyer s Reaction (p. 189), (b) by fusing the corresponding sulphonic acid (or its salts)... 

This direct sulphonation should be compared with the indirect methods for the preparation of aliphatic sulphonic acids, e.g., oxidation of a thiol (RSH -> RSOjH), and interaction of an alkyl halide with sodium sulphite to give the sodium sulphonate (RBr + Na,SO, -> RSO,Na + NaBr). 

This method has the great advantage over method (A) in that it can be applied in particular to those aromatic nitriles in which the aryl group is readily sulphonated clearly, it can also be applied to nitriles in which the alkyl or aryl portion contains groups which are in any other way affected by concentrated sulphuric acid, or by concentrated aqueous alkalis. 

Chemical methods may be employed if the reagent attacks only one of the components. Thus quicklime may be employed for the removal of water in the preparation of absolute ethyl alcohol. Also aromatic and unsaturated hydrocarbons may be removed from mixtures with saturated hydrocarbons by sulphonation. 

If, however, the water formed is removed as formed (compare the preparation of di-n-butyl ether. Section 111,57), the sulphuric acid may react completely and the method may be employed for the preparation of the free sulphonic acid. 

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 chlorosulphonanilide 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. 

Method 1. Equip a 1 litre three-necked flask (or bolt-head flask) with a separatory funnel, a mechanical stirrer (Fig. II, 7, 10), a thermometer (with bulb within 2 cm. of the bottom) and an exit tube leading to a gas absorption device (Fig. II, 8, 1, c). Place 700 g. (400 ml.) of chloro-sulphonic acid in the flask and add slowly, with stirring, 156 g. (176 ml.) of pure benzene (1) maintain the temperature between 20° and 25° by immersing the flask in cold water, if necessary. After the addition is complete (about 2 5 hours), stir the mixture for 1 hour, and then pour it on to 1500 g. of crushed ice. Add 200 ml. of carbon tetrachloride, stir, and separate the oil as soon as possible (otherwise appreciable hydrolysis occurs) extract the aqueous layer with 100 ml. of carbon tetrachloride. Wash the combined extracts with dilute sodium carbonate solution, distil off most of the solvent under atmospheric pressure (2), and distil the residue under reduced pressure. Collect the benzenesulphonyl chloride at 118-120°/15 mm. it solidifies to a colourless sohd, m.p. 13-14°, when cooled in ice. The yield is 270 g. A small amount (10-20 g.) of diphen3 lsulphone, b.p. 225°/10 mm., m.p. 128°, remains in the flask. 

Hydrolysis of a sulphonamide. Mix 2 g. of the sulphonamide with 3-5 ml. of 80 per cent, sulphuric acid in a test-tube and place a thermometer in the mixture. Heat the test-tube, with frequent stirring by means of the thermometer, at 155-165° until the solid passes into solution (2-5 minutes). Allow the acid solution to cool and pour it into 25-30 ml. of water. Render the resulting solution alkaline with 20 per cent, sodium hydroxide solution in order to liberate the free amine. Two methods may be used for isolating the base. If the amine is volatile in steam, distil the alkaline solution and collect about 20 ml. of distillate extract the amine with ether, dry the ethereal solution with anhydrous potassium carbonate and distil off the solvent. If the amine is not appreciably steam-volatile, extract it from the alkaline solution with ether. The sulphonic acid (as sodium salt) in the residual solution may be identified as detailed under 13. 

The Ar and/or Ar group(s) will contain sulphone groups and if Ar = Ar then identical products may be obtained by the two routes. Polyetherification processes form the basis of current commercial polysulphone production methods. These will be discussed further below. 

Phosphorus and Silicon in Waters, Effluents and Sludges [e.g. Phosphorus in Waters, Effluents and Sludges by Spectrophotometry-phosphomolybdenum blue method. Phosphorus in Waters and Acidic Digests by Spectrophotometry-phosphovanadomolybdate method. Ion Chromatographic Methods for the Determination of Phosphorus Compound, Pretreatment Methods for Phosphorus Determinations, Determination of silicon by Spectrophotometric Determination of Molybdate Reactive Silicon-1 -amino-2-naphthol-4, sulphonic acid (ANSA) or Metol reduction methods or ascorbic acid reduction method. Pretreatment Methods to Convert Other Eorms of Silicon to Soluble Molybdate Reactive Silicon, Determination of Phosphorus and Silicon Emission Spectrophotometry], 1992... 

This method is sometimes used for separating hydrocarbons, one of w hich is more easily sulphonated than another. The sulphonic acid is separated from the unchanged hydrocarbon, and the hydrocarbon is then regenerated from the sulphonic acid. 

Another method of obtain"ing vanillin from guaiacol is as follows Formic aldehyde is allowed to react with guaiacol in the presence of phenylhydroxylamine sulphonate —... 

Gattefoss6 and Morel La Parfumerie Moderne, 1919, 114) describe a method for the production of vanillin by reducing nitrobenzene-sul-phonic acid with iron filings and hydrochloric acid in the presence of guaiacol and formic aldehyde. The first-named body is reduced to phenyl-hydroxylamine-sulphonic acid, which reacts with the guaiacol as follows —... 

Thymol has since been synthetised by a number of chemists, but only two of those syntheses need be considered in this connection because of their close relationship to the present method, Dinesmann (D.E.P., 125,097 (1900)) obtain a patent for a process of making thymol from 2-brom-p-cymene. This process consists in sulphonating 2-brom-p-cymene, obtaining 2-brom-3- or 5-sulphonic acid, which, when heated with zinc dust and ammonia in an autoclave at 170°, gives cymene-3-sulphonic acid. This compound on fusion with potassium hydroxide gives thymol. 

The cymidin is now sulphonated, 100 parts by weight of cymidin being slowly added to 69 parts by weight of sulphuric acid (sp. gr. 1 84), contained in a shallow dish, and the solid crystalline mass of cymidin sulphate thus obtai ed is then converted into cymidin sulphonic acid by an identical method to that tised in the so-called baking process for the preparation of stilphanilic acid from aniline sulphate. 

The green colour due to the Cr3+ ions formed by the reduction of potassium dichromate makes it impossible to ascertain the end-point of a dichromate titration by simple visual inspection of the solution and so a redox indicator must be employed which gives a strong and unmistakable colour change this procedure has rendered obsolete the external indicator method which was formerly widely used. Suitable indicators for use with dichromate titrations include AT-phenylanthranilic acid (0.1 per cent solution in 0.005M NaOH) and sodium diphenylamine sulphonate (0.2 per cent aqueous solution) the latter must be used in presence of phosphoric) V) acid. 

Procedure. To obtain experience in the method, the purity of analytical-grade potassium chlorate may be determined. Prepare a 0.02M potassium chlorate solution. Into a 250 mL conical flask, place 25.0 mL of the potassium chlorate solution, 25.0mL of 0.2M ammonium iron(II) sulphate solution in 2M sulphuric acid and add cautiously 12 mL concentrated sulphuric acid. Heat the mixture to boiling (in order to ensure completion of the reduction), and cool to room temperature by placing the flask in running tap water. Add 20 mL 1 1 water/phosphoric(V) acid, followed by 0.5 mL sodium diphenyl-amine-sulphonate indicator. Titrate the excess Fe2+ ion with standard 0.02M potassium dichromate to a first tinge of purple coloration which remains on stirring. 

B. Naphthaquinone method Discussion. Many primary amines develop a blue colour when treated with ortho-quinones the preferred reagent is the sodium salt of l,2-naphthaquinone-4-sulphonic acid. 

Using sulphonic acid ion-exchange resins in ether solvent, selective removal of the trimethylsilyl group from oxygen in bistrimethylsilylated terminal alkynols can be achieved. This method is particularly suitable for low-molecular-weight compounds, where water solubility would make efficient extraction from an aqueous layer difficult. 

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