Monosubstituted Compounds

Developmental toxicity is shown by the disubstituted methyl-, butyl-, and octyltins, but not by the corresponding monosubstituted compounds. The major reported effect is teratogenicity, with effects on fetuses shown at doses close to maternally toxic ones in most cases. NOAELs for dimethyltin, dibutyltin, and dioctyltin are 10 (10), 2.5 (1.0), and 45 (30) mg/kg body weight per day for teratogenicity (maternal toxicity NOAELs in parentheses). 

In addition, data are available for a study on the degradation of dimethyl-, dibutyl-, and dioctyltin chlorides in soil (Terytze et al, 2000). It is of note that the results of the degradation testing indicate that the diorganotin compounds are partially degraded to the corresponding monosubstituted compounds by way of example, dioctyltin concentrations were observed to decrease from 40 to 12 ng/1 over a 3-month period while the monooctyltin concentration stayed relatively constant at around 2 ng/1. It is therefore likely that only a fraction of dioctyltin decayed to monooctyltin and/or the... 

Even though sulfuryl chloride and sulfuryl fluoride can be considered as the disubstituted acid halides of sulfuric acid, the monosubstituted derivatives are also useful compounds that undergo many reactions a result of the reactive -OH group. The monosubstituted compounds can be prepared by the following reactions ... 

The pentafluorophenyl derivatives are particularly revealing, since the polarization transferred to the individual 19F positions can be compared and correlated with different concepts of their interactions with the primarily spin polarized protons [48]. The enhancement factors achieved in the hydrogenation products of monosubstituted compounds at low field under ALTADENA conditions are given in Figure 12.32. 

In general, furoxans are fairly stable compounds in acid solution but are sensitive to bases [6, 9]. This is true in particular for the parent ring and for the 4- and 3-monosubstituted compounds. The former undergoes extensive decomposition, while the latter two produce a-hydroxyimino substituted nitrile oxides 5 and a-nitro substituted nitriles 6, respectively. 4-Aryl-3-methylfuroxans 7, unlike their 4-methyl isomers, give Angeli s rearrangement, namely they are converted to the corresponding 3-arylisoxazolin-4-one oximes 8, by the action of concentrated alkali hydroxides or alkoxides (Scheme 6.1). 

Table 13 shows that this behaviour is completely inverted in the case of iridium here the monosubstituted compounds are rare and the tetrasubstituted derivatives are most commonly found. The following related reasons are believed to be responsible for this behaviour ... 

A disubstitutd derivative, R-CH = CH-R should react twice as fast as a monosubstituted compound R-CH = CH2. 

Finally, very recently Pallavicini et al., in continuation of a previous study on ortho-monosubstituted compounds, designed and synthesized a series of 2-[(2-phenox-yethyl) aminomethyl]-l,4-benzodioxanes ortho-disubstituted at the phenoxy moiety [99]. The disubstituted analogues were tested for their binding affinities at the three oq-AR subtypes and for the 5-HT1A-R. The affinity values of the new compounds were compared with those of the enantiomers of the 2,6-dimethoxyphenoxy analogue, the well-known oq-AR antagonist WB-4101 (Scheme 8.1), and of the ortho-monosubstituted derivatives. The results suggested some distinctive aspects in the interaction of the phenoxy moiety of monosubstituted and disubstituted compounds with the cqa-AR and the 5-HTiA receptors. A classical (Hansch) QSAR analysis was applied to the whole... 

Selective modification of polyols such as ethylene glycol, 1,3-propylene glycol, or glycerol with butadiene (1) has been studied [7-10]. The monosubstituted compounds are preferred due to their potential applications as surfactants, PVC plasticizers, or even in cosmetics. The telomerization of 1 with ethylene glycol yields a complex mixture including linear and branched mono- and ditelomers, as well as 1,3,7-octatriene and vinyl cyclohexene (Fig. 2) [11]. 

Of the tetrahydronaphthalene derivatives (III-VI) required for this work, all of the monosubstituted compounds (III and IV) are known. However, IVa and IV6 were prepared from 5,6,7,8-tetra-hydro-l-naphthoyl chloride by Rosenmund reduction and by reaction with dimethyleadmium, respectively, rather th n by previously published methods. 

Determine p and c from a least squares fit of log kB versus [Pg.534]

In marked contrast to pyran-2-one, electrophilic substitution in (216) occurs readily at C-3, giving the monosubstituted compounds (216 R = N02, Br, SO3H). As might be expected, (216) is susceptible to nucleophilic attack. Heating with 10% aqueous sodium hydroxide results in the formation of a-coccinic acid (218). 

Forthe monosubstituted compounds, the aromatic carbon atom connected to the functional group was selected as the prime atom and was assigned as position 1. 

Only data for substituents of the requisite symmetry are included in Fig. 19. These results adhere to the correlation with excellent precision. This observation confirms the general utility of the procedure. One caution is necessary. The p-value determined for non-catalytic bromina-tion of the monosubstituted compounds is — 12.1. The reaction parameter is decreased to — 8.7 for the bromination process with the polymethylbenzenes. The large variation in substituent effects is presumably the consequence of the greater overall reactivity of the alkylated benzenes. The dependence of p on the nature of the substrate is an important problem worthy of further attention. 

Based on observations for relative basicity of hydrocarbons, assignment of position of protonation is based on theory. Reaction constant evaluated as —11.0 from very limited data for basicity of monosubstituted compounds. 

The reactions of Sn(CH3)4 and Pb(CH3)4 with (CF3)2Hg were also examined. They result solely in the monosubstituted compounds CF3Sn(CH3)3 and CF3Pb(CH3)3 which were obtained in 20 and 94% yields, respectively. The reaction of CF3Sn(CH3)3 with (CF3)2Hg was found to result in only trace amounts of the disubstituted species, (CF3)2Sn(CH3)2 (103). 

When substrate 1 accepts one electron, it forms the radical anion 1, which by fragmentation at the more labile C-leaving group bond affords a radical 2 that by reaction with the nucleophile forms the radical anion of the monosubstituted compound 3. This radical anion can transfer its extra electron to the substrate and in this case the monosubstituted compound 4 with retention of one leaving group is formed (Sch. 2). 

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