T. I. Guseva

Silicon-containing esters of ?-cyanoacrylic acid: synthesis and properties

A number of cyanoacetates have been synthesized: cyanoacetoxymethyitrimethylsilane (1), cyanoacetoxymethylpentamethyldisiloxane (2), cyanoacetoxyetoxymethylpentamethyldisiloxane (3). They were converted by the Knoevenagel reaction to novel esters of a-cyanoacrylic acid (4–13) containing silicon atoms in the ester groups and having the general formula RCH=C(CN)COOCH2X (where R=H, 4-MeOC6H4, MeCH=CH, 2-furyl; X=SiMe3, SiMe2OSiMe3, CH2OCH2SiMe2OSiMe3). These compounds are capable of copolymerization with esters of cyanoacrylic acid which are the precursors to adhesives for cold curing.

Electrophilic 1,3-C→N− and-N→C− migrations in saturated systems

A new type of intramolecular electrophilic rearrangements involving the shift of COOAlk groups from carbon to an N-anionic center is considered. Carbanionic species with COOAlk groups at anionic centers containing no acidic hydrogen react unusually with alkyl(aryl) iso(thio)cyanates giving carbamates as a result of insertion of RNCX into the C−C bond. The kinetics and mechanism of insertion of aryl isocyanates into the C−C bond of the phosphonium zwitterion obtained from triisopropylphosphine and ethyl 2-cyanoacrylate are discussed. The reaction of α-carbanions derived fromN,N-disubstituted amides with methyl trifluoromethanesulfonate results inO-methylation. Some possibilities of back N→C− migrations are considered.

Synthesis of functionally substituted 2-cyanoacrylates

The conditions for the Knoevenagel synthesis of 2-cyanoacrylates containing double and triple bonds in the alkoxycarbonyl group have been studied. It was found that the esters are formed in 10–70 % yields by the condensation of the respective cyanoacetates with formaldehyde in the 1∶1 ratio in the presence of piperidine, followed by the pyrolysis of the oligomers formedin vacuo at 170–200 °C in the presence ofpara-toluenesulfonic acid. The compounds synthesized readily undergo polymerization at room temperature and can be used as the basis for thermostable rapidly polymerizing adhesives.

Synthesis of 2-cyanoacrylatesvia 2-cyanoacryloyl chloride

Monomers that are difficult to obtain, such as tert-butyl 2-cyanoacrylate, trimethylsilyl-methyl 2-cyanoacrylate, 2,2,3,3-tetrafluoropropyl 2-cyanoacrylate, and the previously unknown adamantyl 2-cyanoacrylate were prepared starting from 2-cyanoacryloyl chloride.

SYNTHESIS OF FUNCTIONALLY SUBSTITUTED CYANOACETATES

Some new cyanoacetates were synthesized and characterized. They are precursors for α-cyanoacrylates used as rapidly polymerized, cold-hardening adhesives.

Reactivity of esters of 2-cyanoacrylic acid toward some free radicals

The rate constants for the addition of ·CH(Ph)CH2CCl3, ·CH2Ph, ·CH2Prn, and ·CCl3 radicals to the ethyl 2-cyanoacrylate molecule were determined by ESR spectroscopy using the spin trapping technique.

Intramolecular electrophilic rearrangements in saturated acyclic systems. Reactions of bis-carbanions with isocyanates

The reactions of mono- and bis-isocyanates with bis-carbanions whose COOAlk groups at the anionic centers do not contain acidic hydrogen atoms proceed unusually to form bis-carbamates (including oligomeric carbamates) due to migration of the alkoxycarbonyl groups from the carbon to the nitrogen atom.

Reaction of α-cyanoacrylates with functionally substituted thiols, ethanedithiol, and hydrogen sulfide

Functionally substituted thiols, i.e., thioglycolic acid and cysteamine and cysteine hydrochlorides, facilely undergo addition at the double bond of α-cyanoacrylates, forming the corresponding adducts in quantitative yields: R′SCH2CH(CN)COOR [R′=CH2COOH; CH2CH2NH2·HCl; CH2CH(COOH)NH2·HCl]. Under similar conditions, the reaction with ethanedithiol gives the diadduct [CH2SCH2CH(CN)COOR]2; the monoadduct HSCH2CH2SCH2CH(CN)COOR is formed in a significantly lower yield. Hydrogen sulfide does not undergo addition to α-cyanoacrylate in the absence of a catalyst; S[CH2CH(CN)COOR]2 is formed quantitatively in the presence of Et3N. In the presence of triethylamine, this sulfide undergoes intramolecular cyclization (the Ziegler-Thorpe reaction) with formation of 4-amino-5-cyano-3,5-bis(ethoxycarbonyl)thiacyclohex-3-ene.

The thermodynamics of allyloxyethyl-α-cyanoacrylate, its polymerization and the polymer obtained at 0–330 K☆

Adiabatic and isothermal calorimetry have been used to study the thermodynamic properties of allyloxy-ethyl-α-cyanoacrylate and polyallyloxyethyl-α-cyanoacrylate and the following properties have been determined: the isobaric heat capacity of the monomer and the polymer in the range 11–330 K, the glass-transition parameters and the parameters of the glassy state of the monomer, the energy of combustion of the monomer and the polymer. The following thermodynamic functions have been calculated from the experimental data obtained: H0(T) − H0(0), S0(T) and G0(T) − H0(0) for the range 0–330 K, and the enthalpy of combustion and the thermodynamic parameters of formation, ΔHf0, ΔSf0 and ΔGf0. These results been used to calculate the enthalpy, entropy and the Gibbs function for the polymerization of allyloxyethyl-α-cyanoacrylate in bulk in the range 0–330 K and the upper limiting temperature for polymerization has been estimated.

Synthesis of adamantane monomers and their properties

ConclusionSyntheses were reported for new adamantane monomers, namely the allyl and propargyl esters of 1-adamantanecarboxylic acid, the diallyl and dipropargyl esters of 1,3-adamantanedicarboxylic acid and di-1-adamantyl maleate. These esters are capable of undergoing thermal copolymerization with α-cyanoacrylate esters.