Functional Polymers from (Vinyl)polystyrene. Short Routes to Binding Functional Groups to Polystyrene Resin through a Dimethylene Spacer:  Bromine, Sulfur, Phosphorus, Silicon, Hydrogen, Boron, and Oxygen

Abstract

Many spacer-containing functional polymers were produced by modifying beads of (vinyl)polystyrene, as obtained by free-radical suspension polymerization of a commercial 55:45 divinylbenzene:ethylstyrene mixture, or from commercial sources. Thus, in the presence of free-radical initiators, compounds HBr, HPR2, HP(OR)2, and HSR (R = various alkyl, aryl or acyl, some also containing further COOH/R, OH/R, SH/R, N(H/R)2 groups) underwent anti-Markovnikov addition to the residual vinyl groups. Similar free-radical functionalization with various HSiR3 also proved feasible but more difficult. Other products corresponding to formal anti-Markovnikov addition of H2S, HSO3 -, HP(OH)2, H2, HBR2, HOH, and HOSO2R were obtained by other mechanisms, or after further modifications. FTIR spectra of the resulting functional polymers often showed complete or near-complete disappearance of initial vinyl groups and their replacement by the expected spacer-supported functionalities. The polymer products were also characterized by elemental analysis and solid-state NMR. Many of these functionalized beads, or their further derivatives upon functional group modification, could act as stable and effective solid-phase reagents, catalysts, sequestering agents, or protecting groups for solid-phase synthesis.

Synthesis of Functional Polymers by Post‐Polymerization Modification

“…In the presence of a suitable radical source or under UV irradiation, thiols undergo addition to alkenes predominantly in anti-Markovnikov fashion. [51] Schlaad and Justynska have demonstrated that poly(1,2-butadiene) can be used as a platform to create different side-chain-functionalized polymers. [53] This reaction is tolerant towards a wide range of functional groups, including carboxylic acids, amines, and alcohols (Scheme 5).…”

A Post‐Modification Strategy for the Synthesis of Uniform, Hydrophilic/Hydrophobic Patterned α‐Hydroxy Acid Oligomers

“…The 1 H NMR spectra further indicate that the radical addition of the different thiols to 7 proceeded in the expected anti-Markovnikov fashion. [46,[54][55][56][57][58][59] Markovnikov addition products should have produced a multiplet at 1.2-1.3 ppm due to the additional methyl groups and one or two quartets between 2.7-3.0 ppm due to additional methylene groups adjacent to the sulfur atoms, which are absent in the spectra in Figure 4. The ESI-TOF mass spectra of the post-modified dimers 14, 15 and 16 are shown in Figure 5 Table 2 provided the starting point for the post-modification of the longer oligomers 10 and 13.…”

Linkers for Solid‐Phase Peptide Synthesis

“…Owing to limited stability of this O-benzyl linkage towards acids, homobenzyl (phenethyl) derivatives have also been developed [23][24][25][26].…”