Aliphatic thiol

In fact, perfluoroalkyl iodides can react with thiolates even in the absence of UV irradiation [55, 62, 63] However, the photochemical reaction is particularly useful for the transformation of aliphatic thiols [59], because the spontaneous condensation gives a considerable quantity of disulfide in that case (equations 53-55). 

Molecular ion The presence of sulfur can be detected by the 34S isotope (4.4%) and the large mass defect of sulfur in accurate mass measurements. In primary aliphatic thiols, the molecular ion intensities range from 5-100% of the base peak. 

Thiols react more rapidly with nucleophilic radicals than with electrophilic radicals. They have very large Ctr with S and VAc, but near ideal transfer constants (C - 1.0) with acrylic monomers (Table 6.2). Aromatic thiols have higher C,r than aliphatic thiols but also give more retardation. This is a consequence of the poor reinitiation efficiency shown by the phenylthiyl radical. The substitution pattern of the alkanethiol appears to have only a small (<2-fokl) effect on the transfer constant. Studies on the reactions of small alkyl radicals with thiols indicate that the rate of the transfer reaction is accelerated in polar solvents and, in particular, water.5 Similar trends arc observed for transfer to 1 in S polymerization with Clr = 1.4 in benzene 3.6 in CUT and 6.1 in 5% aqueous CifiCN.1 In copolymerizations, the thiyl radicals react preferentially with electron-rich monomers (Section 3.4.3.2). 

Bystryakov et al. [36] described a double detection method to determine aliphatic thiols by HPLC. A solution of 0.1-1 mg/mL of such compounds in the mobile phase was analyzed by HPLC using a of Nucleosil C18 micro-column (5 pm 6.2 cm x 2 mm)... 

The overall degradation of (103) assisted by the cluster [(Cp )2 M o2Co2S3(CO)4] (Cp = CH3C5H4) is the model reaction that best resembles the heterogeneous counterparts, particularly those classified as Co/Mo/S phase,158 in terms of both structural motif and HDS activity.229 Morever, the Co/Mo/S cluster has successfully been employed to show that the C—S bond scission in the desulfurization of aromatic and aliphatic thiols occurs in homolytic fashion at 35 °C and that thiolate and sulfido groups can move over the face of the cluster as they are supposed to do over the surface of heterogeneous catalysts.230... 

This gap in our knowledge is now closed, as the first paper on the uncatalyzed outer-sphere oxidation of an aliphatic thiol was recently published (12).This work selected thioglycolic acid (TGA, mercaptoacetic acid, HSCH2CO2H) as a representative thiol because of its high water solubility, low vapor pressure, and simple structure. The oxidant was [IrCle]2-, a well-characterized one-electron oxidant that frequently reacts through an outer-sphere mechanism. As is typical of such... 

There have been fewer studies of the reactions of M ions with potential ligand molecules. Laser ablation, which has been the major ionization source for the production of bare metal ions, produces very few negative ions. Electron impact with low-energy electrons (12 eV) of metal carbonyls has been used to produce [Co(CO)4]- and Fc( CO)4 from Co2(CO)8 and Fe(CO)5. Collision-induced dissociation of these two anions produced Co- and Fc, which could be isolated. Both Co- and Fe were reacted with H2S, aliphatic thiols, aromatic thiols, CS2, and disulfides (153). Reactions with H2S gave the metal monosulfide anion [MS]-, which reacted with H2S by two pathways. 

The reaction of the aliphatic thiols gave three initial products. 

Aromatic and aliphatic thiols are oxidized by quaternary ammonium dichromate salts to disulphides (8, 13]. Yields are very good, even with the oxidative dimerization of diethyl phosphorothiolothionate to the corresponding disulphide (79%). 

The optical purity of a- and /J-thiol carboxylic esters, a-thiolamides, secondary benzylic thiols and aliphatic thiols can be measured by l3PNMR using a nonchiral divalent phosphorus... 

Research Focus Cell-occlusive membranes prepared from aliphatic thiols and polyethylene... 

Irradiation of aliphatic thiols, sulfides, and disulfides with a mercury lamp produces gaseous products identified by the mass spectrograph. Thiols are the least stable to light, with the formation of hydrogen95-129 as the main product. Sulfides and disulfides yield, as the predominant products, saturated hydrocarbons of structures corresponding to the smallest alkyl radical attached to sulfur. Haines et al.95-97 have offered a mechanism to explain the predominant production of hydrogen during photolysis of thiols. 

Desulfuration of thiols.2 Aromatic, benzylic, and aliphatic thiols are converted into hydrocarbons when heated in acetic acid with molybdenum carbonyl. The bridgehead adamantane-l-thiol is an exception and gives instead a thioester, RSCOCHj. Yields are 50-90%. The actual reagent is probably tetrakis(acetato)-dimolybdenum.3 Molybdenum carbonyl deposited on silica can also be used. 

The direction of ring opening of nnsymmetnea) episulfides by thiols in the presence of either acid or base catalyst appears to be rather non-selective.1 Mixtures of primary and tertiary mercaptan have been obtained by reaction of isobutylene Bulfido with some of the simple aliphatic thiols such as -butanethiol in the presence of catalytic quantities of either boron trifluoride or sodium ethoxide (Eq. 43). 

The addition of aromatic and aliphatic thiols, RSH and ArSH, and a thioacetic acid to isoprene yields mainly the trans-1,4-adduct (56). The aromatic thiyl radicals, ArS, add almost entirely to the first carbon atom however, aliphatic thiyl radicals, RS, also add to the fourth C atom in significant amounts. 

Primary Sulfonium Ions. Aliphatic thiols are completely protonated in HS03F-SbF5 diluted with S02 at -60°C [Eq. (4.30)].149... 

J oshi and coworkers reported the first catalytic oxidation of thiols using an iron(III) complex (Table 3.4) [153]. Fem-EDTA proved to be an excellent catalyst for the oxidation of a variety of aromatic, aliphatic and heterocyclic thiols under alkaline conditions using molecular oxygen as the primary oxidant. Aromatic thiols were found to be more reactive than aliphatic thiols, for which the reactivity was strongly dependent upon the pH of the medium. 

Aromatic and aliphatic thioles RSH (R = 2-, 3-, or 4-tolyl, 2-hydroxyethyl, 2-ethoxyethyl, 4-chlorphenyl, etc.) in the presence of a base yield anionic dithiolatorhodium(III) porphyrins (path j) which show the so-called hyperporphyrin spectra and are susceptible to autoxidation yielding hyperoxide ions. Although the formation of the latter ones is formulated via a nucleophilic exchange of coordinated OJ with thiolate, it could well be that an outer-sphere electron transfer between he anionic bis(thiolato) complex and molecular dioxygen initiates the observed formation of disulfides RSSR. 

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