Volatile sulfonated compounds

GC analysis of underivatized polar fractions did not reveal any volatile sulfur compounds. However, once these fractions were methylated with diazomethane, a number of sulfur compounds were detected. (Presumably, the diazomethane methylated either carboxylic acid, phenolic, thiophenolic, sulfonic acid or even alcohol or thiol groups and thereby increased their parent molecules volatility). These additional sulfur compounds are currently under investigation in our laboratories and the results of these studies will be reported later. 

Socher, G. et al. Analysis of sulfonated compounds by reversed-phase ion-pair chroma-tography-mass spectrometry with on-line removal of non-volatile tetrabutyl ammonium ion-pairing agents. Chromatographia 2001,54, 65—70. 

Electron diffraction and microwave spectroscopy have been used to determine the conformational preferences for some simple, volatile sulfonic acids and derivatives. The findings have been summarized by Hargittai24. Compounds 56 to 61 exist as staggered conformers. 

Organic residual components are the most worrying because of their toxicity. Some of these compounds are formed as by-products. Volatile organic compounds are determined by headspace GC, GC-MS. Intermediate products, such as sultones and sulfones, from sulfonation of olefin and alkyl-benzene, respectively, can be detected by LC. Unreacted products, like ethylene oxide from the synthesis of ethoxylated nonionic and anionic surfactants, are studied by GC benzyl chloride from the quaternization of tertiary amines and aliphatic amines from amidation reaction are determined by LC (Figure 5). 

Furthermore, it is very important to detect sulfur compounds due to the risk for human health and environment. Most of the sulfur compounds have high toxicity. Organic sulfur compoimds (OSCs) are toxic and mutagenic, and volatile sulfonated compoimds (VSCs) create acid rain, steel corrosion, and malodorous emissions into the atmosphere. 

As sulfonic acid cannot be vaporized, its determination by the direct gas chromatography (GC) method is not possible. To enable determination by GC, the reactivity of the S03H group is used the esterification of the S03H group with diazomethane via acid chloride is one way to transfer the sulfonic acid to volatile compounds. By conversion of the sulfonic acid with phosphoric acid at 200-210°C, the S03H group is cleaved and the hydrocarbons are obtained [184-186]. 

Oxime carbamates are not directly amenable to gas chromatography (GC) because of their high thermal instability, which often leads to their breakdown at the injection port or in the column during analysis. Analysis of oxime carbamates by GC with sulfur detection or flame photometric detection involves oxidation of the intact insecticides or alkaline hydrolysis to form the more volatile but stable oxime compound. Enzymatic techniques have been reported for the analysis of these compounds. Enzyme-linked immunosorbent assay (ELISA) has been used to determine aldicarb and its sulfone and sulfoxide metabolites and methomyl in water, soil, and sediment samples. 

In contrast to the other large cats, the urine of the cheetah, A. jubatus, is practically odorless to the human nose. An analysis of the organic material from cheetah urine showed that diglycerides, triglycerides, and free sterols are possibly present in the urine and that it contains some of the C2-C8 fatty acids [95], while aldehydes and ketones that are prominent in tiger and leopard urine [96] are absent from cheetah urine. A recent study [97] of the chemical composition of the urine of cheetah in their natural habitat and in captivity has shown that volatile hydrocarbons, aldehydes, saturated and unsaturated cyclic and acyclic ketones, carboxylic acids and short-chain ethers are compound classes represented in minute quantities by more than one member in the urine of this animal. Traces of 2-acetylfuran, acetaldehyde diethyl acetal, ethyl acetate, dimethyl sulfone, formanilide, and larger quantities of urea and elemental sulfur were also present in the urine of this animal. Sulfur was found in all the urine samples collected from male cheetah in captivity in South Africa and from wild cheetah in Namibia. Only one organosulfur compound, dimethyl disulfide, is present in the urine at such a low concentration that it is not detectable by humans [97]. 

Typically, only 0.01-10% of the mass of pesticide compounds applied to fields is detected in streams [91]. The remaining 90-99% of pesticides adsorb to soil, percolate into groundwater, or volatilize [79]. The major degradates of the most heavily used herbicides found in surface water have not been studied widely. Many chemical properties of pesticides affect the amounts transported to streams. In general, acetanilide herbicides are more soluble in water, and thus more mobile than are the triazines [92], The solubilities of sulfonated degradates of acetanilides (ethane sulfonic acid, or ESA), can be 10 times the solubility of the parent compound [93]. The greater mobilities of the degradates of the acetanilides (amide family) can explain these com-... 

Continuous operations are feasible and practical (1) where the organic compound (benzene or naphthalene) can be volatilized, (2) when reaction rates are high (as in the chlorosulfonation of paraffins and the sulfonation of alcohols), and (3) where production is large (as in the manufacture of detergents, such as alkylaryl sulfonates). 

Volatile profiles of raw and cooked-beef flavor samples, prepared by the procedures of Figure 1, were obtained after capillary GC and FPD. Although the identification of these sulfur containing compounds is as yet incomplete, the chromatograms demonstrated that there were a number of new sulfur compounds produced on cooking that were not present in the raw beef. Three prominent sulfur compounds were identified as markers in subsequent meat flavor deterioration experiments, namely, methional (13.2 min), methyl sulfone (13.8 min), and benzothiazole (25.3 min). Each compound produced an adequate mass spectrum for spectral library search and positive identification. 

Tetramethylsilane became the established internal reference compound for H NMR because it has a strong, sharp resonance line from its 12 protons, with a chemical shift at low resonance frequency relative to almost all other H resonances. Thus, addition of TMS usually does not interfere with other resonances. Moreover, TMS is quite volatile, hence may easily be removed if recovery of the sample is required. TMS is soluble in most organic solvents but has very low solubility in water and is not generally used as an internal reference in aqueous solutions. Other substances with references close to that of TMS have been employed, and the methyl proton resonance of 2,2-dimethylsilapentane-5-sulfonic acid (DSS) at low concentration has emerged as the reference recommended by IUPAC for aqueous solutions.55 Careful measurements of the DSS-TMS chemical shift difference when both materials are dissolved at low concentration in the same solvent have shown that for DSS 5 = + 0.0173 ppm in water, and 8 = — 0.0246 ppm in dimethyl sulfoxide. Thus, for most purposes, values of 8 measured with respect to TMS or DSS can be used interchangeably. 

We hope that the creativity of chemists dealing with synthesis of cyclophanes as well as synthesis of other classes of compounds will be stimulated to try new, creative syntheses of sophisticated, strained molecules. Thus, in view of successful fourfold-pyrolyses and the availability of the modification for sulfones of low volatility [18], sixfold-pyrolyses of sulfones promise some potential. This synthetic method will be undispensable for the synthesis of large, complex, and sophisticated molecules. 

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