摘要:
Production of 2-alkyl or 2-cycloalkyl-4-methyl-6-hydroxy pyrimidines by first reacting diketene and lower alkanoic or cycloalkanoic acid amides in the presence of catalytic amounts of Lewis bases or Lewis or Bronsted acids, followed by treating the N-acetoacetyl (lower) alkanoic or cycloalkanoic acid amide intermediates with ammonia in the presence of acid catalysts.
摘要:
The present invention relates to a process for forming a composite article in a resin transfer molding system. The process includes the steps of providing a fiber preform in a mold, injecting a matrix resin into the mold, allowing the matrix resin to impregnate the fiber preform, and heating the resin impregnated preform to at least about 200.degree. F. for sufficient time to produce at least a partially cured solid article. The matrix resin comprises 1) a liquid epoxy resin component selected from the group of a phenolic novolac epoxy resin,, a cycloaliphatic epoxy resin and mixtures thereof; 2) an epoxy diluent; and 3) at least one latent curing agent that cures only when subjected a temperature of at least about 200.degree. F. The partially cured solid article may be subjected to post-curing operations to produce a final composite article. The present invention also relates to a process for forming a composite article in a vacuum assisted resin transfer mold system.
摘要:
Production of 2-alkyl- or cycloalkyl-4-methyl-6-hydroxypyrimidines by first neutralizing an alkyl imidate ester hydrochloride with a base in the presence of a water-immiscible solvent for the alkyl imidate ester to be freed thereby; condensing the alkyl imidate ester with diketene to form an oxazinone intermediate, which is then reacted in organic solution with gaseous ammonia and recovering the desired substituted 6-hydroxypyrimidine.