Mustard cation

The first four compounds have lower j values than methyl bromide because each is quite reactive in itself and therefore is not very dependent on help from the nucleophile /-toluenesulfonate is a good leaving group and does not need much assistance to begin to depart ring strain in propiolactone and in the mustard cation make a ring-opening Sv2 reaction very favorable and the transition state of benzyl chloride is stabilized by resonance and therefore is easily reached. 

CH2-). By contrast with the aliphatic thiolates, the length of the alkyl chain appears to exert little influence on the nucleophilicity of a thioadd. This is indicated by the fact that the substrate selectivities of mustard cation (0-chloroethylethylenesulfonium ion) are virtually identical for the attack by CH3CSS- and C4H9CSS- (Table VII). 

In Table VI the E and H values have been computed for four thio anions using the kinetic data of Ogston el al. (1948) on the mustard cation. 

Tentative Values of E and R Based on the Competition Teems of Ogston et al. (1948) on Mustard Cation... 

As the term of Eq. (20) measures the sensitivity of the substrate to the basicity of the nucleophile, it is reasonable to suspect that j3 is a measure of the acidity of the substrate. The term is an acid-base term. The trend of /3 values of Table V can be predicted. The more positive the center being attacked the larger is Thus the mustard cation... 

Cohen JB, Sharp SD, Liu WS. 1991. Structure of the agonistbinding site of the nicotinic acetylcholine receptor. [ H] acetylcholine mustard identified residues in the cation binding subsite. J Biol Chem 266 23354-23364. 

Reaction of the sandwich-type POM [(Fc(0H2)2)j(A-a-PW9034)2 9 with a colloidal suspension of silica/alumina nanopartides ((Si/A102)Cl) resulted in the production of a novel supported POM catalyst [146-148]. In this case, about 58 POM molecules per cationic silica/alumina nanoparticle were electrostatically stabilized on the surface. The aerobic oxidation of 2-chloroethyl ethyl sulfide (mustard simulant) to the corresponding harmless sulfoxide proceeded efficiently in the presence of the heterogeneous catalyst and the catalytic activity of the heterogeneous catalyst was much higher than that of the parent POM. In addition, this catalytic activity was much enhanced when binary cupric triflate and nitrate [Cu(OTf)2/Cu(N03)2 = 1.5] were also present [148],... 

Like sulfur mustard, the nitrogen mustards combine predominantly with the thiol group of molecules and are excreted as conjugated cysteinyl derivatives. Both nitrogen and sulfur mustards have structural similarities and have common chemical reactions. A key reaction is the intramolecular cyclization in a polar solvent such as water to form a cyclic onium cation and a free anion. Nitrogen mustards form the immonium cation, while the sulfur mustard forms the sulfonium cation. The cyclized form is responsible for the varied effects of mustards, which are similar. In nitrogen mustard the sulfur is replaced by nitrogen. 

In the S type of reaction characteristic of the nitrogen-mustards, the cation of the drug, e.g. (13.43) which is formed relatively slowly, attacks the anion of the biopolymer rapidly, and the product is neutral alternatively this cation... 

Mustard gas slowly hydrolyses in water and forms hydrochloric acid and thiodiglycol. Both final products of the hydrolysis are non-toxic. The hydrolysis is dependent on temperature, density, viscosity, pH value and pressure. Because mustard gas is relatively insoluble, the slower dissolving process is the main factor of interest here. There is a huge difference between distilled water and normal sea water. In distilled water the half-life is 8.5 minutes at 25oC, while for salt water at the same temperature the half-life is 60 minutes. For sea water the hydrolysis will be slowed down by a factor of more than 3 times. The pace of hydrolysis of sulphur mustard gas also depends on the content of salt (cations and anions) in an aqueous solution. The reported half-life of sulphur mustard gas in sea-water is 15 minutes at 25oC, 49 minutes at 15oC, and 175 minutes at 5oC. ... 

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