CA Preparations

A process for preparing methyl .alpha.-cyanoacrylate in which methyl cyanoacetate is reacted with formaldehyde to form a polymer, which is subsequently depolymerized to the monomeric product, comprises using an ester of poly(ethylene glycol) as the solvent for the polymerization and depolymerization reactions.

Prepn. of methyl alpha-cyanoacrylate comprises reacting methyl cyanoacetate with HCHO in a solvent of a poly(ethylene glycol)di-acetate, dipropionate, or dibutyrate, having a number average molecular wt. of 200-400. The formed polymer is then depolymerised to the monomeric prod. the purity of yield is 96% or better.

In order to study structure-tissue reactivity relationships and ultimately develop a less necrotizing adhesive, this laboratory undertook a study of the synthesis and degradation of the homologous series of α-cyanoacrylate monomers and polymers. A method for synthesizing high purity cyanoacrylates and some of their chemical and physical properties and presented. In vitro kinetics studies under heterotgeneous and homogeneous conditions indicate that cyanoacrylate polymers degrade by hydrolytic scission of the polymer chain.

A series of alkyl 2-cyanoacryloyl glycolate tissue adhesives were synthesized and characterized by NMR. Physical properties and bond strengths are presented. Within the series, bond strength decreased with increasing molecular weight. Corresponding polymers were evaluated by in vitro and in vivo techniques for biocompatibility. In general, in vitro biocompatibility increased with molecular weight.

a-cyanoacrylate compounds expressed by the following general formula: wherein R' desianates- and R2 designates alkyl groups, alkenyl groups or alkynyl groups of C1 to C4. These compounds are preferably synthesized by the reaction of the compounds expressed by the following general formula: wherein R' and R2 are same as the above described, with formaldehyde products and then the depolymerization of the resulting dehydrating condensation polymers. These compounds are effectively used as fast-setting adhesives.

Ethoxyethyl α-cyanoacrylate was synthesized by first making oligo(ethoxyethyl α-cyanoacrylate) through a condensation reaction of ethoxyethyl cyanoacetate with paraformaldehyde, followed by a depolymerization of the oligomer at an elevated temperature in an acidic atmosphere with a high vacuum. The ethoxyethyl cyanoacetate was in turn synthesized from an esterification of ethoxyethanol and cyanoacetic acid. The molecular structure of the target monomer and the corresponding intermediates were corroborated by IR and 1H-NMR.

The adhesive bond of allyl 2-cyanoacrylate between steel substrates has been analyzed and compared to that of ethyl 2-cyanoacrylate. Mechanical strength as well as thermomechanical, calorimetric, thermogravimetric, and dynamic mechanical response was observed. It was demonstrated that the allyl 2-cyanoacrylate bonds exhibit improved temperature resistance owing to the formation of heat-induced crosslinks in the adhesive layer, resulting in much improved lap-shear strengths.

This invention is related to the preparation of alkyl or alcoxyalkyl-&agr;-cyanoacrylates in monomeric form by depolymerisation of the corresponding poly(alkyl-&agr;-cyanoacrylates) or poly(alcoxyalkyl-&agr;-cyanoacrylates) (PCA). The PCA's are obtained preferably by base-catalyzed condensation of a cyanoacetate with formaldehyde (or a polymer of the latter).