Synthesis, Characterization, and Catalytic Properties of Diphenyl- and Dichlorobutyltin Functionalities Grafted to Insoluble Polystyrene Beads by a −(CH₂)_n− (n = 4, 6) Spacer

Abstract

Insoluble diorganotin functionalized polymers of the type (P-H) 1-t (P-(CH 2 ) n SnBuX 2 ) t , with n ) 4, 6, X ) Ph, Cl, and t being the degree of functionalization, were synthesized from Amberlite XE-305, an insoluble polystyrene (P-H) cross-linked with divinylbenzene. The synthesis conditions used gave rise to functionalization degrees varying from 25% to 30%. The tin-functionalized polystyrenes were characterized by elemental analysis, IR, and Raman as well as solid-state 117 Sn and 13 C NMR spectroscopy. Methodological and chemical features related to the determination of the functionalization degree have been investigated in detail. The catalytic activity of the Amberlite-grafted tin functionalities in transesterification reactions was studied.

Catalytic properties of cross‐linked polystyrene grafted diorganotins in a model transesterification and the ring‐opening polymerization of ε‐caprolactone

“…The general reaction scheme for the synthesis of the polystyrene grafted dialkyldichlorotin compound (1) 26 and the corresponding distannoxane (2) 25,28 is described in detail elsewhere and recalled in Scheme 2. The complete characterization by infrared/Raman spectrometry, elemental analysis, and one-and two-dimensional hr-MAS NMR spectroscopy has also been described previously for the grafted dialkyldichlorotin.…”

“…The complete characterization by infrared/Raman spectrometry, elemental analysis, and one-and two-dimensional hr-MAS NMR spectroscopy has also been described previously for the grafted dialkyldichlorotin. 25,26,34,35 The grafted distannoxane derivative was thoroughly characterized for the C4-and C6-spacers only. 27,28 No direct evidence for the existence of a grafted tetraalkyldichlorodistannoxane with a dimeric ladder structure, similar to that of the soluble molecular nongrafted analog, 2,7 -12,32 has been found so far, mainly because the two characteristic isotropic chemical shifts from the endo and exo tin atoms in the four-membered Sn 2 O 2 ring core were never formally identified in the grafted C4-and C6-analogs.…”

“…117 Sn MAS NMR spectra did not show the characteristic two isotropic chemical shifts to be expected for such an Sn 2 O 2 ring core for C4-and C6-grafted chlorodistannoxane. 25,27,28 The solid-state 117 Sn MAS NMR spectra recorded at two different spinning rates for the grafted C11-analog, compound 2, are shown in Fig. 1(d, e), together with the spectrum for a nongrafted molecular analog, tetra n-butyldichlorodistannoxane analog [ Fig.…”

“…It also confirms that the additional cross-linking of the diorganotin units at the interface, resulting both from the Sn-O-Sn bridge formation and the rather unexpected dimerization of two such moieties to the ladder structure with central Sn 2 O 2 four-ring core, dramatically decreases the conformational flexibility and mobility of the organotin moieties, with the consequence that any 119 Sn hr-MAS resonance from the interface of 2 simply becomes invisible [ Fig The functionalization degree t of the grafted C11-distannoxane was determined from elemental analysis data using a previously described non-linear least-squares procedure. 25 The elemental analysis results are given in the experimental section, along with the corresponding calculated data. 27 The values are pair-wise in excellent agreement with each other, which evidences the high functional purity of compound 2.…”

“…7 -12 In non-grafted molecular form, such tetraalkyldichlorodistannoxanes display dimeric ladder structures in solid as well as in solution, 2 with two constitutionally different pairs of mutually homotopic endo and exo tin atoms involved in a four-ring Sn 2 O 2 distannoxane core. 32,33 In spite of numerous data on polystyrenegrafted chlorodistannoxanes with tetramethylene C4-and hexamethylene C6-spacers, 25,28 it has never been elucidated whether such distannoxanes, when grafted, can keep such dimeric configurations, probably submitted to demanding grafting constraints (Scheme 1). The present paper solves this issue.…”