Synthesis and Reactions of Cyanic Esters

Abstract

In experimental work, reliable and accurate means of the detection and measurement of hydrophobic bonding are lacking. In the interpretation of the effect of noncovalent interactions upon the thermodynamic behavior of solutes in general and upon the conformation of macromolecules in particular, the so far unsolved question of additivity must be raised: Is the total contribution of various types of noncovalent interactions the sum of the individual contributions of each of them, as determined by composition and spatial arrangement and according to parameters derived from simple model compounds, or do the various interactions perturb each other? The question has been discussed by Ne'methy et al. [211, Tanford 1231, and Wetlaufer et al.1331. It seems that the effects of various functional groups are approximately additive. However in exact quantitative treatments deviations from additivity will have to be considered explicitly. f n 1963, it was found that sterically unhindered esters of cyanic acid, which had previously been considered unobtainable, could be easily prepared from phenols and cyanogen halides. Another synthesis, involving the thermolysis of thiatriazole derivatives, was discovered in 1964. The aryl cyanates in particular have since been found to have many uses as starting materials for the preparation of numerous new classes of compounds [e.g. derivatives of esters of imidocarbonic acid (, etc.], mainly by addition of nucleophilic or I,3-dipolar reactants, or as aids e.g. in the elimination of H 2 0 or H2S or in the transfer of CNgroups.The preparation of true esters ( I ) of cyanic acid, i.e. those in which the organic group is bonded to the oxygen, was a problem that remained unsolved for a very long time. Since cyanic acid always reacted in the is0 form (2b) to give isocyanates (3) [I], attempts were made as early as the second half of the 19th century to synthesize the molecule ( I ) by combination of a component ROwith a component -CN. However, cyanates could not be obtained either by the reaction of esters of hypochlorous acid with cyanides [2,31 or In 1895 it was reported by Nef[91 and by Hantzsch and Mai[lol that the reaction of phenoxides (alkoxides) with cyanogen halides leads only to imidocarbonates( 4 ) and cyanurates ( 5 ) . Though Nef regarded (6) as a n intermediate in the formation of (4), and considered ( 5 ) to result from the decomposition of (4) with elimination of phenol [91, it seems reasonable to assume that the products (4) and (5) are in fact formed by further reaction of an initially formed cyanate.An exception is the reaction of sterically hindered o-substituted phenols with cyanogen chloride, which according to Stroh and Gerber [111 represents the first preparation of true cyanate esters. The expected Angew. Chem. internat. Edit. VoI. 6 (1967) No. 3 [23] E. Mulder, Recueil Trav. chim.

Hydrogen-bond interactions between poly[(ethyl acrylate)-co-(acrylic acid)] and polycyanate derived from bisphenol A dicyanate

“…It is interesting to further apply this strong H-bond interaction to a thermoset/linear polymer system, and to explore the possibility to generate a homogeneous blend through physical instead of chemical interactions in the TGDDM/PC case as described above 1) . Since the first preparation by Grigat and Putter 9,10) , aromatic dicyanates have gained increasing attention due to their important applications in industry. Polycyclotrimerization of aromatic dicyanates can generate a crosslinked network (polycyanate) with s-triazine rings as interconnecting junction points ( Fig.…”

Quantitative Gas-Solid Reactions with ClCN and BrCN: Synthesis of Cyanamides, Cyanates, Thiocyanates, and Their Derivatives

“…[13] Cyanamides are very useful reagents for a multitude of intermolecular syntheses. [14] Thus, their quantitative production is of particular value.…”

Synthesis and characterization of new dicyanate monomers. A way to obtain fully aromatic crosslinked poly(ether ketone)s

“…The cyanate monomers were synthesized by following the Grigat and Pü tter method, 23,24 by reacting the phenolic precursors with cyanogen bromide in the presence of triethylamine. The presence of an electron-withdrawing substituent (as the ketone group is) in the aromatic ring has been reported to produce some imidocarbonate groups when reaction is carried out at 0°C 25 and preferentially when at room temperature.…”