MIXED ARYL-ALKYL ORGANOTIN COMPOUNDS

In an effort to develop new organotin materials for investigation and biocidal evaluation a series of compounds containing mixed aryl-alkyl substituents have been synthesized, ArylMe2SnCl. The synthetic route chosen involves the initial formation of unsymmetrical organotin compounds, (Aryl)2SnMe2 (R = Η (1), Et (2), i-Pr (3), t-Bu (4), hexyl (5), octyl (6)), from the reaction of Me2SnCl2 and the appropriate aryl Grignard, followed by cleavage of one aryl group with hydrogen chloride. This study has led to the development of a high yielding synthetic route for the formation of (p-RC6H4)SnMe2Cl (R= Η (7), Et (8), iPr (9), t-Bu (10), hexyl (11), octyl (12)). As well as complete 'H, ' X , n 9 Sn NMR spectroscopic data, the single crystal X-ray structural analysis of 10 is also presented illustrating the self-assembled chains involving pentacoordinate tin with two non-equivalent CI atoms. Introduction The interest in, use of, and concern about the utility of organotin biocides has a long history and despite recent restrictions on their usage many aspects of structure/reactivity remain to be uncovered (1). Very recently Gitlitz reported on the synthesis of unsymmetric triorganotrn compounds containing exclusively alkyl groups, RR'2SnCl (2). We report the related synthesis, including a single crystal X-ray structural analysis, of the mixed aryl/alkyl chlorides (p-RC6U4)Me2SnCl, which surprisingly are not reported in the literature, even for R = Η (3). Experimental Dimethyldichlorotin, bromobenzene, l-bromo-4-ethylbenzene, 1-bromo-4-isopropylbenzene, 1bromo-4-terbutyibenzene and 1 Μ HCl in diethyl ether were purchased from Aldrich and used as received; l-bromo-4-n-hexylbenzene and 1-bromo-4-octylbenzene were purchased from Alfa Aesar. Solvents were dried by standard methods, and distilled prior to use and the manipulations were carried out under a nitrogen atmosphere. Elemental analysis performed by Galbraith Laboratories. Arvlation of organotin halides by the Grignard method. All Ar2SnMe2 compounds were synthesized using the same procedure and the specific synthesis of 1 is provided below as illustrative of these reactions. Experimental results, spectroscopic and analytical data are presented in Tables 1, 2 and 5 respectively. Synthesis of diphenyidimethyltin (1). In a 250mL three-necked flask, equipped with a condenser and a dropping funnel, 3.2 g of magnesium turnings with 40 mL of THF were placed. To this was added dropwise a solution of bromobenzene 20 g (127 mmol) in 40 mL of THF. The addition of a few crystals of iodine was sufficient to initiate the reaction. The reaction was then refluxed for three hours. After completion the Grignard reagent was added dropwise to a solution of dimethyldichlorotin (14 g, 63 mmol) in 40 mL of THF at 0°C. The mixture was stirred for 15 h. The solvent was removed under reduced pressure and the residue was extracted with hexane. The resulting solution was filtered and the solvent was removed to give a clear liquid material, which upon fractional distillation at 140°C/0.1 mm Hg gave 1, (14 g, 46 mmol, 77%). Table 1. Experimental data for Aiyl2Me2Sn, RPhMgBr + Me2SnCl2 — Aryl2Me2Sn RProduct b.pt(m.pt*)° Yield Η 128 64 Ph2SnMe2 140 77 Et 55 27.5 (EtPh)2SnMe2 160 82 i-Pr 26 13 (;-PrPh),SnMe2 160 80 t-Bu 76 38 (i-BuPh)-,SnMe2 87* 87 hexyl 20 10 (hexylPh)2SnMe2 210 63 octyl 37 18.5 (octylPh>SnMe2 240 54 mmoles of reagent (RPh)2SnMe, HCl 0.1 mm/H Chlorination of Aryl2Me2Sn to form ArylMe2SnCI.The preparation of 7 is outlined below as typical of the general method used for this process. Experimental results, spectroscopic and analytical data are provided in Tables 2 and 5 respectively.