Phthalimidomethyl trithiocarbonates are used as reversible addition fragmentation chain transfer (RAFT) agents to provide low polydispersity α-(phthalimidomethyl)polystyrene with number-average molecular weight in the range 1000−100000 g mol-1. The activity of the phthalimidomethyl trithiocarbonates in RAFT polymerization of styrene, which appears to be similar to that of analogous benzyl trithiocarbonates, is attributed to the electrophilic character of the phthalimidomethyl group. The trithiocarbonate functionality in the products was quantitatively transformed to inert chain ends either by radical-induced reduction with tributylstannane or by thermal elimination, allowing the phthalimido end groups to be cleanly converted to primary amine end groups by hydrazinolysis. Thermolysis experiments, in which the polymers are cleaved at the trithiocarbonate linkage, also provide information on the mechanism of RAFT polymerization. In the case of the symmetrical bis(phthalimidomethyl) trithiocarbonate the two c...

Synthesis of well-defined polystyrene with primary amine end groups through the use of phthalimido-functional RAFT agents

Here we describe the preparation of 25 beaded polystyrene−poly(ethylene glycol) graft copolymers from six spectroscopically active styrene monomers:  styrene, 2,5-dimethylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 4-tert-butylstyrene, and 3-methylstyrene. These polymers were thoroughly characterized by Raman, infrared, and 1H/13C NMR spectroscopies, and differential scanning calorimetry. Determination of the swelling properties, peptide synthesis, and on-bead streptavidin−alkaline phosphatase (SAP) binding assay further established that their physical and chemical properties where not significantly altered by the diversity of their encoded polystyrene core. Each of the 25 resins displayed a unique Raman and infrared vibrational fingerprint, which was converted into a “spectroscopic barcode”. The position of each bar matches the peak wavenumber in the corresponding spectrum but is independent of its intensity. From this simplified representation similarity maps comparing 35 000 resin pairs were generat...

Preparation, physical properties, on-bead binding assay and spectroscopic reliability of 25 barcoded polystyrene-poly(ethylene glycol) graft copolymers.

Free radical polymerization of cyclohexyl acrylate involving interconversion between propagating and mid-chain radicals

We report an operationally simple protocol for the catalytic α-deuteration of styrenes. This process proceeds via the base-catalyzed reversible addition of methanol to styrenes in DMSO-d6 solvent. The concentration of methanol is shown to be critical for high yields and selectivities over multiple competing side reactions. The synthetic utility of α-deuterated styrenes for accessing deuterium-labeled chiral benzylic stereocenters is demonstrated.

Catalytic α-Selective Deuteration of Styrene Derivatives.

Radical polymerization, co-polymerization, and chain transfer of α-substituted acrylic esters

During the synthesis of α-(hydroxymethyl)acrylate using the DABCO catalyzed addition of formaldehyde to the corresponding acrylate, it was observed that ether and acetal products were formed. An ene-type mechanism for ether formation previously proposed involving a six-membered ring transition state with essentially simultaneous transfer of a proton, loss of water, and ether bound formation is confirmed by 1 H and 13 C NMR study

Mechanism study of the base-catalyzed ether formation involving α-(hydroxymethyl)acrylates

: A simple, direct exchange reaction has been discovered for vinyl groups in which the exchangeable deuterium of alcohols (e.g. CH3OD) or water (D2O) replaces only the alpha-hydrogen of activated vinyls under catalysis by DABCO (1,4-diazabicylo-(2.2.2.) octane). Acrylate esters, acrylonitrile, acrylamides and methyl vinyl ketone were found to go rapid exchange at room temperature to give easily isolated, pure and readily polymerizable alpha-deuterated compounds. This procedure is the most general efficient and cost-effective one available for obtaining such isotopically labeled materials.

Facile Synthesis of Alpha-Deuterated Acrylics and Activated Vinyls.

Synthesis and wide-line NMR studies of α-deuterated polyacrylates and polyacrylonitrile

Characterization of Methyl Alpha-Hydroxymethylacrylate Ether Cyclopolymer Using Nutation NMR Spectroscopy

The serendipitous formation of 2,5-dimethoxy- 1,4-benzoquinone is reported from the reaction of 1,4-benzoquinone with methanol, DABCO, and paraformaldehyde. This monomer, and its di-n-butoxy analog, are also available from 2,5-dihydroxy-1,4-benzoquinone. These materials are capable of novel polycondensation reactions with diamines such as 1,6-hex-anediamine. Use of m-crexsol as polymerization solvent gave a dark, insoluble product while various amide solvents lead to orange or pink polymers that had average degrees of polymerization from 5 up to >30. These polymers, Plus model compounds obtained from 1-aminopropane and N,N'- dimethyl-1,6-hexanediamine, were characterized by FTIR, solution, and solid-state NMR.

Ronald F. Colletti

Papers

Mechanism study of the base-catalyzed ether formation involving α-(hydroxymethyl)acrylates

Facile Synthesis of Alpha-Deuterated Acrylics and Activated Vinyls.

Synthesis and wide-line NMR studies of α-deuterated polyacrylates and polyacrylonitrile

Characterization of Methyl Alpha-Hydroxymethylacrylate Ether Cyclopolymer Using Nutation NMR Spectroscopy

2,5,‐Dimethoxy‐ and 2,5‐di‐n‐butoxy‐1,4‐benzoquinone reactions and polymerization with 1,6‐hexanediamine