General Procedure for the Michael Addition Reaction
of Indole with Pyrrole Catalyzed by Feist's Acid (G[P.sub.2]).
When the reaction was performed using [Br.sub.2] as a catalyst without adding any bromoform, only isomerized product was formed with no addition reaction
taking place in all three methods.
Vinyl (1,2) microstructure dominates the poly(butadiene) resin (90% of monomer units), and addition reactions
may dominate the cure mechanism.
(5-7) Commercial ASPE-based diamines are derived from the Michael addition reaction
between aliphatic diamines and diethyl maleate (DEM).
This was already observed in the results section and it was explained by the decrease in residual unsaturation upon increasing the peroxide level, due to enhanced addition reactions
, and the subsequent decreased susceptibility for further crosslinking during aging.
Alkenes in general are known to undergo addition reactions
at lower temperatures and allylic substitution at higher temperatures.
Alkenes are known to undergo addition reactions
at lower temperatures and/or isomerization at higher temperatures.
Of course, the desired reaction pathway for a polymer radical (Po) is crosslink formation either through coupling with another polymer radical or addition reactions
through in-chain or pendant double bonds (unsaturated elastomers).
Kinetic Model for Michael Addition Reactions
. The following elementary reactions based on the proposed Michael addition reaction
mechanism shown in Scheme 2 are considered:
This issue covers reactions of aldehydes and ketones and their derivatives; reactions of carboxylic, phosphoric and sulfonic acids and their derivatives; oxidation and reduction; carbenes and nitrenes; nucleophilic and electrophilic aromatic substitution; carbocations; nucleophilic aliphatic substitution; carbanions and electrophilic aliphatic substitution; elimination reaction; addition reactions
(polar addition and cycloaddition); and molecular rearrangements.
The common reactions which occur with the carbodiimides, - N = C = N--, occur as addition reactions
. The R groups attached to the carbodiimide functionality determine selectively what type of addition reactions
occur and under what kinetically driven conditions.
The kinetic model simulation has to be able to either describe the complete cross-linking process phenomenologically (4) or mechanistically (5-7) including homolytic cleavage of the peroxide, beta cleavage of the oxy radical, hydrogen abstraction, addition reactions
, radical coupling (cross-link formation), polymer scission, and radical transfer for a wide range of compositions and an assortment of elastomers, using a single set of rate constants.