Aryl dicyanate

Cyanate esters are a family of aryl dicyanate monomers that contain the reactive cyanate (-0-C=N) fimctional group. When heated, this cyanate functionality undergoes an exothermic cyclotrimerization reaction to form triazine ring connecting units, resulting in the formation of a thermoset polycyanate polymer. 

Woo Woo, E. M., Shimp, D. A., Seferis, J. C. Phase stmcture and toughening mechanisms of a thermoplastic-modified aryl dicyanate. Polymer 35 (1994) 1658-1665. 

Aryl dicyanate esters, NCO-Ar-OCN, appear to have several unique and interesting features ... 

S-(Dicyan-methyl)-isothioharnstofTliefert beim Erwarmen in Gegenwart von aromatischen Al-dehyden unter Cyclisierung und Kondensation in niedrigen Ausbeuten 4-Amino-2-aryl-... 

Dimethylamino-l-oxo-l-phcnyl-propan und l,3-Diphenyl-3-oxo-propen2150,2408 3-Aryl-l-dimethylamino-3-oxo-propenen2408d 3-Oxo-alkansaure-nitrilen1035-1361 Dicyan-butendisaure-dinitrilen2150... 

Alkyl(Aryl)-l, 3-dicyan-4-oxo-4H-[Pg.1018]

Zur Herstellung von Thiobenzoesdure- und subst. Thiobenzoesdure-O-ethylestern (74 95%) aus Aryl-nitrilen s.Lit.102. Aus 2,5-Dicyan-pyridin erhalt man fiber das Bis-carbon-saure-methylester-imid das orange 2,5-Bis-(methoxy-thiocarbonyl)-pyridin (50%)1O2a. 

Cyanate/Cyanurate. When aryl cyanate esters are heated to 150 to 250°C, they cyclotrimerize to cyanuric acid esters (Fig. 3.62). They can be catalyzed by organo-metallic and active hydrogen compounds. When the monomer is a dicyanate such as bisphenol A dicyanate (Fig. 3.63), the result is a highly cross-linked heterocyclic polymer (Table 3.57). Using a novolac polycyanate has produced Tg and useful life over 300°C. 

Aryl cyanate esters such as bisphenol A dicyanate can be processed much like epoxy resins for many applications. This may be implied by comparing the monomer structure of bisphenol A diglycidyl ether to bisphenol A dicyanate. 

Cyanogen chloride and dicyan are poisonous. For safety reasons, nowadays the less toxic aryl cyanates have become the preferred cyano sources. They react smoothly with both organomagnesiums and organolithiums. The treatment of a-chloro-l-alkenyllithium 208 with 1-naphthyl cyanate provides the product in 87% yield... 

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