Sulphides aliphatic

A number of other aliphatic sulphide polymers have appeared with the general structure (1) as opposed to the older materials of type (II) typified by the Thiokol materials ... 

Blocking of reaction sites The interaction of adsorbed inhibitors with surface metal atoms may prevent these metal atoms from participating in either the anodic or cathodic reactions of corrosion. This simple blocking effect decreases the number of surface metal atoms at which these reactions can occur, and hence the rates of these reactions, in proportion to the extent of adsorption. The mechanisms of the reactions are not affected and the Tafel slopes of the polarisation curves remain unchanged. Behaviour of this type has been observed for iron in sulphuric acid solutions containing 2,6-dimethyl quinoline, /3-naphthoquinoline , or aliphatic sulphides . 

Many S compounds, especially aliphatic sulphides, do not give accurate results, since the sulphones formed by the action of HN03 are generally so stable as to resist further decomposition by the acid. When stable sulphones are formed the contents should be washed out into a nickel basin, made alkaline with KOH, and evaporated to dryness. The residue is then treated as described in the fusion method. 

Davies MJ, Gilbert BC, Norman ROC (1984) Electron spin resonance, part 67. Oxidation of aliphatic sulphides and sulphoxides by the sulphate radical anion (S04 ) and of aliphatic radicals by the peroxydisulphate anion S Os2 ). J Chem Soc Perkin Trans 2 503-509 Dizdaroglu M, Gajewski E, Reddy P, Margolis SA (1989) Structure of a hydroxyl radical induced DNA-protein cross-link involving thymine and tyrosine in nucleohistone. Biochemistry 28 3625-3628... 

Chlorination not accompanied by oxidation occurred on treatment of aliphatic sulphides and phenylated dimethyl sulphide with 3-(dichloroiodo)pyridine in chloroform for example, methyl ethyl sulphide afforded a mixture of the two monochlorinated sulphides (CH2CISCH2CH3 and CH3SCHCICH3) in a ratio of 1 3 [25]. 

By far, the most extensive studies and applications of (dichloroiodo)benzene involved the direct conversion of aliphatic sulphides into a-chlorosulphoxides. Related results were reported for the chlorination of sulphoxides to a-chlorosulphoxides, especially from the stereochemical point of view. Generally,... 

Aromatic and aliphatic sulphides, thioethers, thiols, thioamides and thiocarbamates may undergo oxidation to form sulphoxides and then, after further oxidation, sulphones (figure 4,23). This is catalysed by a microsomal mono-oxygenase requiring NADPH and cytochromes P-450. The FAD-containing mono-oxygenases will also catalyse -oxidation reactions. 

To elucidate the mechanism of transformation of phenolic sulphides, some data can be used dealing with transformations of aliphatic sulphides, applied as synergistic additives, or with transformations of aromatic sulphides. However, the relationships should be extrapolated only very carefully. Further experimental data are necessary to establish the whole transformation mechanism of phenolic sulphides. 

Stabilization of an a-carbanion by divalent sulphur is the result of the polarizability of the sulphur atom rather than conjugation - and the same basis is suggested for the enhanced acidity of an a-proton in aliphatic sulphides. TT-Donating abilities for various heteroatoms towards an adjacent carbonium ion centre follow the series P>S>N>0>C1> F, implying (in contrast to current ideas) that a Period 3 element in the system X—CH2+ is a better Tr-electron donor than the corresponding Period 2 element. 

Aliphatic thiols have been subjected to i.r., Raman, and microwave spectroscopic studies. Methyl and ethynyl groups are gauche in ethyl vinyl sulphide, as judged from microwave data. I.r./Raman studies of aliphatic sulphides and disulphides similarly include interpretation in terms of conformation or bonding. Comparative i.r./Raman studies of dimethyl sulphide, sulphoxide, and sulphone and the corresponding diphenyl series have been described. I.r. spectra of selenuranes and sulphones and sulphimides have been inter-... 

Other Physical Properties.—Conformational information for thiols and sulphides can be obtained from enthalpy of formation data. Proton-transfer of benzyl-mercaptan (protonation at sulphur with CF3SO3H, and de-protonation by imidazole) has been studied. Thermodynamic parameters for acidity constants of substituted benzenethiols, and for hydrogen-bonding interactions between alkanols and di-n-octyl sulphide and the analogous ether and N-methylamine, reveal a dominant electronic influence of the orM<>-substituent, and substantially higher hydrogen-bond acceptor ability for the aliphatic sulphide than is generally assumed. ... 

Saturated Aliphatic Sulphides Aryl Sulphides.— Reactivity of aryl alkyl sulphides towards Br2 in AcOH decreases in the order Pr, Et, Me, though the opposite order applies to the oxygen analogues. 

Azodicarboxylate esters give a-substitution products with aliphatic sulphides [e.g. R SCHjR gives R SCHR N(C02Et)NHC02Et] " u.v.-irradia-tion improves yields. Chloromethyl p-tolyl sulphide gives a -epoxy-sulphides (cis-trans mixtures) with aldehydes, catalysed by DABCO, thus completing the series a(3-epoxy-sulphide, sulphoxide, sulphone. 

A modification to the alkene ozonolysis reaction employs dimethyl sulphide to reduce the ozonide to a keto-aldehyde. Decomposition of benzoyl poroxide is accelerated by aliphatic sulphides or disulphides, owing to nucleophilic attack by sulphur at oxygen. An extension of work described in 1%9 by the same authors showing the ability of sulphides and thiols to quench pffioto-excited benzophenone has been described. ... 

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