Nitration of α,β-unsaturated esters. Evidence for positive charge build-up adjacent to carbonyl carbon
作者:Stuart A. Hewlins、John A. Murphy、Jian Lin、David E. Hibbs、Michael B. Hursthouse
DOI:10.1039/a607170h
日期:——
Reactive intermediates formed in the nitration of certain
α,β-unsaturated esters with nitronium tetrafluoroborate
exhibit behaviour expected of highly reactive α-carbonyl cations.
Three diagnostic reaction types have been observed which indicate the
presence of these destabilised cations: (i) trapping in a Ritter
reaction, (ii) cyclopropane formation from propyl cations, (iii)
WagnerâMeerwein migration of alkyl groups. Semi-empirical
calculations of the relative gas-phase stabilities of the proposed
intermediate cations are useful in rationalising the observed
chemistry.
Anomalous nitrations of αβ-unsaturated esters: a role for α-carbonyl cations?
作者:Stuart A. Hewlins、John A. Murphy、Jian Lin
DOI:10.1039/c39950000559
日期:——
Reaction of α,β-unsaturated esters with nitronium tetrafluoroborate at â16 °C affords products which suggest the intermediacy of highly reactive α-carbonyl cations.
Alternating copolymers of isobutylene type monomers
申请人:——
公开号:US20030170394A1
公开(公告)日:2003-09-11
A copolymer composition that includes a copolymer comprised of at least 30 mol % of residues having the following alternating residues from a donor monomer and from an acceptor monomer. The copolymer contains at least 15 mol % of an isobutylene type donor monomer and at least 15 mol % of an acrylic monomer as an acceptor monomer. The copolymer is substantially free of maleate or fumarate monomer segments and the copolymer composition is substantially free of Lewis acids and transition metals. Also disclosed is a thermosetting composition that includes a reactant comprising functional groups, a crosslinking agent having at least two functional groups that are reactive with the functional groups first reactant, and a copolymer flow control agent that includes the copolymer composition as well as substrates coated with the thermosetting composition.
Thermosetting compositions containing alternating copolymers of isobutylene type monomers
申请人:——
公开号:US20030171497A1
公开(公告)日:2003-09-11
A thermosetting composition that includes an ungelled copolymer composition and a crosslinking agent. The ungelled copolymer composition includes a functional group-containing copolymer that includes segments of alternating residues derived from a donor monomer composition comprising an acceptor monomer composition. The donor monomer composition includes one or both of isobutylene and diisobutylene, and the acceptor monomer composition includes acrylic monomers and monomers containing functional groups. The ungelled copolymer composition is substantially free of transition metals and Lewis acids, and the copolymer is substantially free of maleate-type monomer residues and fumarate-type monomer residues. The crosslinking agent has at least two functional groups that are reactive with the functional groups of the copolymer. The thermosetting composition may be in liquid, powder, or dispersed form and may be applied by traditional or electrocoating methods.