The toxicity of organic sulphides to the eggs and larvae of the glasshouse red spider mite. III.—benzyl phenyl sulphides substituted only by halogens

Abstract

The activities against the eggs and young mites of the glasshouse red spider (Tetvanychus telavzus L.) have been determined for a series of benzyl phenyl sulphides containing only halogen nuclear substituents. The results, together with the results from some of the corresponding sulphoxides and sulphones, are tabulated and discussed. Introductiona description has been given of the activities against the red spider mite, in laboratory tests, of a series of SS'-disubstituted alkane-am-dithiols and, also, of a series of compounds consisting of two benzene nuclei linked by various sulphur-containing bridges. During the preparation of the latter series of compounds, benzyl phenyl sulphide was synthesized and, although the activity of this unsubstituted parent compound was low, it soon became apparent that substitution by halogens in either or both of the benzene nuclei had a profound effect on the activity. As, in addition, these compounds had little or no phytotoxicity, a series of benzyl phenyl sulphides containing only halogen nuclear substituents was prepared and tested.Many of the sulphides were oxidized to the corresponding sulphoxides and sulphones which were also tested for activity, since there was evidence to indicate that oxidation of 9-chlorobenzyl p-chlorophenyl sulphide (chlorbenside) could occur after application on leaf surfaces. 3

The search for exceptions in the highly enantioselective titanium catalysed oxidation of aryl benzyl sulfides

“…Mp 163e165 C (from n-hexane/acetone 3:2), (lit. 16 mp 145e146 C for the racemic sulfoxide). ½a 25 D þ127.9 (c 0.8 in CHCl 3 ).…”

“…Sulfoxide 6b was also obtained in an enantiopure form after crystallisation (Table 1, entry 6). At this stage we considered it of interest to compare the results obtained for 4-bromophenyl 4-iodobenzyl sulfoxide 7b with the oxidation of 4-bromophenyl 4-bromobenzyl sulfide 8a 16 (Table 1, entry 8). Only a slight decrease of the ee value was measured (93% ee) that was soon balanced by a crystallisation step that allowed us to obtain the enantiopure 8b 16 (Table 1, entry 8).…”

“…At this stage we considered it of interest to compare the results obtained for 4-bromophenyl 4-iodobenzyl sulfoxide 7b with the oxidation of 4-bromophenyl 4-bromobenzyl sulfide 8a 16 (Table 1, entry 8). Only a slight decrease of the ee value was measured (93% ee) that was soon balanced by a crystallisation step that allowed us to obtain the enantiopure 8b 16 (Table 1, entry 8). For a better comparison, we also reported in Table 1 the oxidation of the unsubstituted benzyl phenyl sulfide 9a, 17 to give sulfoxide 9b, 18 that had not been previously oxidised with our protocol, and the oxidation of benzyl 4-bromophenyl sulfide 10a, 4 that was reported at the beginning of our investigation on this procedure.…”

“…Therefore, we decided to test for the first time some iodinated non-fluorinated aryl benzyl sulfides. In a first run, we chose to react p-tolyl 4-iodobenzyl sulfide 6a 15 and 4-bromophenyl 4-iodobenzyl sulfide 7a 16 (Table 1, entries 6 and 7). Good isolated yields (84% and 95% respectively) of the corresponding sulfoxides 6b 15 and 7b 16 were obtained having the usual high enantiomeric enrichment value (95 and>98% ee respectively).…”

Reusable BNPs‐SiO2@(CH2)3NHSO3H‐catalysed selective oxidation of sulfides to sulfones

“…[18,19,[37][38][39][40][41][42][43][44][45] All reactions were monitored by TLC. [18,19,[37][38][39][40][41][42][43][44][45] All reactions were monitored by TLC.…”