Cyanuric compounds

Figure 8.25 The planar slruclure of various cyanuric compounds all 6 C-N distances within the ring are equal.

Stilbene Derivatives. Most commercial brighteneis aie bistria2inyl derivatives (1) of 4,4 -diarmnostilbene-2,2 -disulfonic acid (Table 1). The usual compounds are symmetric preparation begias with reaction of 2 moles of cyanuric chloride derivatives with 1 mole of... 

Flame retardants designated for nylon include halogenated organic compounds, phosphorous derivatives, and melamine cyanurate (160—163). Generally, flame retardants are difficult to spin in nylon because of the high loading required for effectiveness and their adverse effects on melt viscosity and fiber physical properties. 

Other examples of DAP copolymerizations of industrial interest include copolymerization with MMA in emulsion (50) and for light focusing rods (51) with vinyl naphthalene for lenses (52) with epoxy acrylates and glass fibers (53) epoxy acrylates and coatings (54) with diacetone acrylamide (55) with ahphatic diepoxide compounds (56) triaHyl cyanurate in lacquers for printed circuits (57) and DAIP with MMA (58). 

ChlorinatedIsocya.nura.tes. The cyanuric acid-based sanitizers, introduced for pool use in 1958, are stable crystalline compounds with moderate-to-high available CI2. Sodium dichloroisocyanurate (Dichlor), sold in granular form, dissolves rapidly, whereas trichloroisocyanuric acid (Trichlor) dissolves very slowly and is widely used in the form of tablets or sticks in feeders, floating devices, or in the pool skimmer. 

Miscellaneous Disazo Dyes. Another group of disazo dyes is prepared by condensation of two identical or different aminoazo compounds commonly with phosgene, cyanuric chloride, or fumaryl dichloride, the fragments of which act as blocking groups between chromophores. 

Stable A/-chloro compounds are formed by reaction of hypochlorous acid and appropriate N—H compounds. For example, HOCl, formed in situ via chlorine hydrolysis, converts di- or trisodium cyanurates to dichloro- and trichloroiso-cyanuric acids, respectively (114). Chloroisocyanurates can also be prepared from isocyanuric acid or monosodium cyanurate and preformed HOCl (115—117). Hydrolysis of chloroisocyanurates provide HOCl for use in swimming pool disinfection and in bleaching appHcations. 

Cyanuric acid is only slightly soluble (<0.1%) at room temperature ia common organic solvents such as acetone, benzene, diethyl ether, ethanol, and hexane (13). SolubiUty is significant ia basic nitrogen compounds (eg, dimethylformamide 7.2%) or unusual solvents such as DMSO (17.4%). SolubiUty ia... 

Although much weaker than the parent compound isocyanic acid (pK = 3.7), CA is sufftciendy acidic to form salts. Many inorganic and organic salts of CA have been reported (11). Lead and 2iuc cyanurates are usehil as corrosion inhibitors (20). The 1 1 adduct, melamine cyanurate [37640-57-6] has achieved commercial importance. 

Peroxide curing systems are generally the same for CSM as for other elastomers but large amounts of acid acceptor must be present to complete the cure. A small amount of a polyfunctional alcohol, ie, pentaerythritol (PER) in the compound significantly reduces the amount of base required by acting as a solubiHzer. TriaHyl cyanurate [101-37-17 is an additional cure promoter and leads to higher cross-link density. 

The ultraviolet and infrared spectra and the crystal structure (as determined by X-rays) of cyanuric acid have been interpreted on the basis of the trioxo structure 157 however, other ultraviolet data have been reported from which it was concluded that approximately 5% of this compound exists in a hydroxy form in solu-tion. The monoanion of cyanuric acid exists as 158. Ultraviolet spectral data suggest that ammelide (159) and ammeline (160) exist as shown (available infrared spectra offer less conclusive evi-... 

Goi. As noted previously, an a-chlorine atom renders a ring-nitrogen atom very weakly basic. Cyanuric chloride (5) is a very weak base both because s-triazines are of low basicity and because each of the ring-nitrogen atoms is alpha to two chlorine atoms. Hence, this compound should be insensitive to acid catalysis or acid autocatalysis and this has been observed for the displacement of the first chlorine atom with alcohols in alcohol-acetone solution and with water (see, however. Section II,D,2,6). 

Compounds of type 6 containing ZR substituents with a -electron pair on the Z atom bound to the ring carbon (Z = O, S, NH) are formed by displacement of the first chlorine atom of cyanuric chloride by weU-known nucleophiles. Their basicity should be greater than that of cyanuric chloride because of the mesomeric electron release of the ZR... 

Even polyalkoxy-s-triazines are quite prone to nucleophilic substitution. For example, 2,4,6-trimethoxy-s-triazine (320) is rapidly hydrolyzed (20°, dilute aqueous alkali) to the anion of 4,6-dimethoxy-s-triazin-2(l )-one (331). This reaction is undoubtedly an /S jvr-4r2 reaction and not an aliphatic dealkylation. The latter type occurs with anilines at much higher temperatures (150-200°) and with chloride ion in the reaction of non-basified alcohols with cyanuric chloride at reflux temperatures. The reported dealkylation with methoxide has been shown to be hydrolysis by traces of water present. Several analogous dealkylations by alkoxide ion, reported without evidence for the formation of the dialkyl ether, are all associated with the high reactivity of the alkoxy compounds which ai e, in fact, hydrolyzed by usually tolerable traces of water. Brown ... 

Poly (Difluoroamino)-Substituted Cyanuric and Isocyanuric Acid Derivatives. For Cyanuric Acid and Derivatives see Vol 3, C589-R ff. For Difluoroamino Compounds see Vol 5, DI258-L... 

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