Sulphur compounds, identification

Determination of the molecular structure of sulphur-containing compounds identification of sulphur functional groups... 

Ledauphin, J., Basset, B., Cohen, S., Payot, X, and Barillier, D. (2006b). Identification of trace volatile compounds in freshly distilled Calvados and Cognac Carbonyl and sulphur compounds. J. Food Comp. Anal., 19, 28 0. 

Kurzawa, J. Kurzawa, Z. A new determination technique of divalent sulphur compounds by induced iodine-azide reaction. Chem. Anal. (Warsaw) 1986, 31,45 52. Kurzawa, Z. Kurzawa, J. Uninduced reaction of sodium azide with iodine. Pol. J. Chem. 1984, 58, 373 376. Sjoquist, J. Paper strip identification of phenyl thiohydan-toins. Acta Chem. Scand. 1953, 7,447-448. 

Wronski, M. Goworek, W. Identification of divalent sulphur compounds by an enthalpimetric approach to the iodine-azide reaction. Analyst 1987,112, 333-334. 

Nuclear Magnetic Resonance Spectra.—Natural-abundance S n.m.r. of representative sulphur compounds appears to offer little scope for structural identification purposes the broad absorption peaks render chemical-shift measurement very inaccurate. Some H- Se and H- Te doubleresonance studies reveal a similar structure-dependence of Se and Te chemical shifts, comparable with that of P. ... 

The identification of geraniol can be confirmed by its conversion into citral, Cj Hj O, its aldehyde, which has a very characteristic odour and yields well-defined crystalline derivatives. Five parts of the alcohol fraction are shaken with 2-5 parts of chromic acid and four parts of concentrated sulphuric acid dissolved in 100 parts of water. The mixture is warmed in the water-bath for a few minutes, when crude citral separates on the surface of the liquid. This is purified by steam distillation and conversion into its sulphonic acid compound in the... 

Tan [71] devised a rapid simple sample preparation technique for analysing polyaromatic hydrocarbons in sediments. Polyaromatic hydrocarbons are removed from the sediment by ultrasonic extraction and isolated by solvent partition and silica gel column chromatography. The sulphur removal step is combined into the ultrasonic extraction procedure. Identification of polyaromatic hydrocarbon is carried by gas chromatography alone and in conjunction with mass spectrometry. Quantitative determination is achieved by addition of known amounts of standard compounds using flame ionization and multiple ion detectors. 

A reversed-phase liquid chromatographic method was developed for simultaneous determination of carboxylic acids, phenolic compounds, and SA in white wines (84). The diluted samples are injected into a Spherisorb ODS-2 column with a gradient of sulphuric acid (pH 2.5)/methanol as mobile phase. A diode array detector is used, set at 210 nm for carboxylic acids and altered to 278 nm, during the run, for phenolics and SA. The identification of compounds is based on retention time and UV spectra. Some cleanup methods (Sep-Pak C18 and an ion-exchange column) were tested and did not improve the results. The analysis was considered simple, with no sample preparation. Application of this method was illustrated by analyses of Brazilian Welchriesling wines (84). 

Rubber tyres are by far the most visible of rubber products. Identification is trivial and collection is well organized. Recycling and disposal, however, are less evident. A major route for tyres is their use as a supplemental fuel in cement kilns. Major compounds in tyres are styrene-butadiene rubber (SBR), synthetic and natural polyisoprene rubber, steel cord, carbon black, zinc oxide, sulphur and vulcanization-controlling chemicals. Tyres can be retreaded, which is economic for large sizes (truck tyres), or ground to crumb or powder (cryogenic grinding). Such materials have some limited market potential as an additive in asphalt, and in surfaces for tennis courts or athletics. 

Fluorescence data have been reported for thirty-one corticosteroids in sulphuric acid, allowing identification of the structural features necessary for strong fluorescence. The u.v. absorption maxima of 4-en-3-ones are red-shifted by amino or quaternary ammonium functions in compounds such as (18) or (19). ... 

NOTE.—Small quantities of benzene and other hydrocarbons can be readily identified by converting them into solid nitro derivatives the melting-points of which can be determined. As little as 2 or 3 drops of benzene is sufficient for the identification of the hydrocarbon in this way. In working with such a small quantity proceed as follows Mix 3 drops of benzene and 1 cc. each of concentrated sulphuric acid and concentrated nitric acid. Boil the mixture for one-half minute. Cool, and pour slowly into 10 cc. of water. Shake, filter by suction ( 42, page 29), and wash with water. Dissolve in a boiling mixture of 4 cc. of water and 4 cc. of alcohol. Set aside to crystallize, filter, wash with 5 cc. of cold 50 per cent alcohol, and dry on a porous plate. The compound prepared in this way melts at 89°-89.5°. 

In many instances it is important to determine the sulphur content in chromato-graphically separable compounds. Klaas [146] developed a method for the identification and determination of trace amounts of sulphur-containing compounds in ligroins. The method consists in selective chromatographic separation, subsequent oxidation and determination of the resulting sulphur dioxide by titration. Huyten and Rinders [147] use hydrogenation to identify the components of a mixture subjected to analysis foUowing... 

Two of the reactions of aldehyde which have been described are much used in the identification of members of this class of compounds, namely, the formation of a mirror when an ammoniacal solution of silver nitrate is gently warmed with an aldehyde, and the change of the latter to a resin when heated with a strong solution of a caustic alkali. If these reactions take place when a substance is treated as described, there is a strong probability that it is an aldehyde. Compounds other than aldehydes, however, reduce an ammoniacal solution of silver salts, and other tests should be applied in addition to the ones just given. When an aqueous solution of rosaniline, which is a red dye, is treated with a saturated solution of sulphur dioxide in water, the color is destroyed. The colorless solution, known... 

Identification of Alkyl Halides.—On account of their relative inertness at ordinary temperatures the alkyl halides are usually identified by the determination of their physical properties. They are insoluble in concentrated sulphuric acid, and, unlike the acyl halides, they do not react readily with water and alcohols. Unlike the compounds in which halogen is joined to nitrogen, they are not easily changed by an aqueous solution of sodium hydroxide. They are distinguished from many halogen derivatives of benzene and related hydrocarbons, which will be described later, by the fact that they are decomposed when boiled with an alcoholic solution of potassium hydroxide —... 

Identification of Nitro Compounds.—The definite identification of a substance as a nitro compound is difficult, as substances exist which are closely related to nitro compounds and show many of the reactions of the latter. Nitro compounds are insoluble in water, but dissolve in many organic solvents. They are, in general, soluble without decomposition in concentrated sulphuric acid, and are precipitated when the solution is poured into water. The specific gravity of nitro compounds is greater than one. When treated with tin and hydrochloric acid, they are reduced to amines. This reaction serves as a valuable test. The nitro compound, which is insoluble in hydrochloric acid, is converted into a salt of an amine, which is soluble. A... 

Identification of Phenols.—The reactions of phenols which are of particular value in their identification, are those that take place with alkalies, ferric chloride, and bromine water. Most phenols react with an aqueous solution of sodium hydroxide to form soluble salts, but are insoluble in a solution of sodium carbonate. The behavior of phenols with these two reagents shows their weakly acidic properties, and serves to distinguish them from acids. Phenols which contain strongly negative substituents decompose carbonates, and show all the properties of acids. It is difficult, therefore, to identify as a phenol substances which contain such substituents. Ferric chloride produces marked colorations in aqueous solutions of most phenols. The reagent produces a similar effect with certain other compounds, and the formation of a color with ferric chloride can be taken, therefore, only as an indication of the presence of a phenol. With bromine water most phenols yield a precipitate of a brominated phenol. Other compounds, amines for example, are also converted into insoluble substitution-products by bromine water. Notwithstanding this fact the test is of value. Many phenols form colored products when heated with phthalic anhydride and concentrated sulphuric acid. The reaction will be described under phenolphthalein (558, 639). 

A d.t.a. study has shown that in the temperature range 500—800 C, SF reacts with oxides of Group II and III elements with considerable evolution of heat. The gaseous products were found to be SO2 and sulphuryl fluoride, with thionyl fluoride being observed in the reaction of AI2O3 with SF. The first matrix-isolation and i.r. spectral identification of the SFs radical, as produced by the vacuum-u.v. photolysis of SF and its derivatives, and by controlled attack by fluorine atom on SF4, has been announced. Compounds of the type SF5— N=S(F)NR2 and SF5—N=S(NR2)2 have been prepared by Si—bond-cleavage reactions of silylamines with pentafluorosulphur-sulphur difluoride imide the... 

---