Cyanates analysis

For colorimetric or gravimetric determination l-nitroso-2-naphthol can be used. For chromatographic ion exchange (qv), cobalt is isolated as the nitroso-(R)-salt complex. The cyanate complex is used for photometric determination and the thiocyanate for colorimetry. A rapid chemical analysis of... 

Capillary tube isotachophoresis using a potential gradient detector is another technique that has been applied to the analysis of alcohol sulfates, such as sodium and lithium alcohol sulfates [303]. The leading electrolyte solution is a mixture of methyl cyanate and aqueous histidine buffer containing calcium chloride. The terminating electrolyte solution is an aqueous solution of sodium octanoate. 

The NCO—CH2(CF2) CH2—OCN monomer series have been characterized by DSC, IR, H-NMR, 19F-NMR, 13C-NMR, and elemental analysis.8 Table 2.1 summarizes the characterization most pertinent to these cyanate ester monomers. The n = 5,1, and 9 members are missing. This is a reflection of the difficulty in obtaining the odd hydrocarbon diol precursors. The trend of a rapid melting point increase with increasing fluoromethylene sequence length is an indication that monomers with n > 10 will probably not be melt-processible since the onset of the cure exotherm in most purified monomers occurs at 200°C. 

Cyanamides, 3 157-171 23 107 economic aspects, 3 162-163 health and safety factors, 3 163-164 manufacture, 3 161 shipping and handling, 3 162 specifications and analysis, 3 163 Cyanate ester curing agents, 20 411 Cyanate ester resins, production of, 23 769 Cyanation, 9 313 Cyanazine, 23 321-322 Cyan couplers, in chromogenic chemistry, 19 252-253 Cyan dyes... 

Sodium compounds, 22 760-761, 762 as soap bar additives, 22 744 Sodium cyanamide, 8 184 Sodium cyanate, 8 184 Sodium cyanide, 8 183-184 analysis, 8 190 economic aspects, 8 189 health and safety factors, 8 190-191 manufacture, 8 187-189 properties, 8 184-187, 185t silver extraction via, 22 638, 646-647 uses, 8 191... 

Analysis of single primers) 27-33 (Analyses of typical priming mixtures, which include MF, Sb sulfide, K chlorate glass K chlorate, Sb sulfide, Pb sulfo-cyanate TNT Pb picrate, red P Ba nitrate K chlorate, Sb sulfide, Pb nitrate TNT K chlorate, Sb sulfide, Pb nitrate, TNT glass MF, Pb picrate, Sb sulfide,... 

Often, greater accuracy may be obtained, as in Volhard type titration, by performing a back titration of the excess silver ions. In such a case, a measured amount of standard silver nitrate solution is added in excess to a measured amount of sample. The excess Ag+ that remains after it reacts with the analyte is then measured by back titration with standard potassium thiocyanate (KSCN). If the silver salt of the analyte ion is more soluble than silver thiocyanate (AgSCN), the former should be filtered off from the solution. Otherwise, a low value error can occur due to overconsumption of thiocyanate ion. Thus, for the determination of ions (such as cyanide, carbonate, chromate, chloride, oxalate, phosphate, and sulfide, the silver salts of which are all more soluble than AgSCN), remove the silver salts before the back titration of excess Ag.+ On the other hand, such removal of silver salt is not necesary in the Volhard titration for ions such as bromide, iodide, cyanate, thiocyanate, and arsenate, because the silver salts of these ions are less soluble than AgSCN, and will not cause ary error. In the determination of chloride by Volhard titration, the solution should be made strongly acidic to prevent interference from carbonate, oxalate, and arsenate, while for bromide and iodide analysis titration is carried out in neutral media. 

The analysis of cyanate is based on its total conversion to an ammonium salt. This is achieved by heating the acidified sample. The reaction is shown below ... 

Sodium chlorite, analysis of, for preparation of chlorine (IV) oxide, 4 156 Sodium cyanate, 2 88 Sodium diimidothiophosphate, formation of, from thiophosphoryl triamide, 6 112... 

Anodic cyanation has been shown to be a direct process by electrochemical methods in conjunction with the analysis of products from cpe experiments (nos. 11 and 34, Table 8). In addition, cyano radicals can be generated in homogeneous solution, and a comparison of processes initiated by radical cation and cyano radical initiated processes reveals the indiscriminate nature of the latter towards aromatic substrates (cf. also Williams, 1960). This is in contrast to the electrophilic nature of the radical cation process. 

They wasted no time. Berzelius supplied the young student with a platinum crucible, a wash bottle, a balance and a set of weights, advised him to buy his own blowpipe, and set him to work on the examination of minerals. That was to be his first training m accurate analysis. When Woehler hurried,to Berzelius to show him the result of his work his teacher warned him, Doctor, that was quick but bad." Woehler remembered this valuable advice. Woehler now turned once more to his recently discovered cyanic acid and succeeded in preparing silver cyanate, a compound of this acid. 

Recently, evidence for the transient ex istence of cation-radicals from simple pyrroles and indoles has been furnished by the observation of anodic regiospecific cyanation of these heterocycles.455 Both heterocycles are preferentially cyanated at the 2-position. Methyl side chains at these positions are also activated to cyanation and deuteration. Indole cation-radicals have been generated by photoionization in an aqueous medium.456 Unsubstituted at N, their lifetime in neutral solution is 10-6sec before they lose the N-proton however, it is longer in more acidic conditions.456 The photophysical properties of indole, its cation-radical, and neutral radical have been the subject of a recent theoretical analysis.457 On anodic oxidation of 2,3-diphenyl indole in acetonitrile, the initially formed cation-radicals dimerize to a product identified, primarily on the basis of 13C NMR, as 3-(5-indolyl)-indolenine (141).458... 

The crystal standard of (7r-cp)2Ti(NCO)2 has been determined and confirms that, in the solid state, the cyanate group is here N-bonded it was only in the last stages of the analysis that the 0-bonded alternative could be finally eliminated (i). Hexa-iV-cyanato complexes of ytterbium, erbium, and neodymium have been reported as quaternary onium salts (16) and reference made to the series of tetraethylammonium salts of [Ln(NCO)0] (Ln = Eu-Yb) (22) these results extend Table XLII. The ESR spectra of series of complexes CuL2(NCO)2 (L = an, or substituted an) have been interpreted to show Cu— N(CO)—Cu bridges with no indication of any Cu-0 interactions (19). The ESCA spectra of [M(NCO)4] (M = Mn, Co, Zn) have been recorded (12). 

There have been several recent investigations into the mechanism of photo-cyanation of aromatic hydrocarbons. The process with naphthalene, biphenyl, and phenanthrene has been subjected to a kinetic analysis the reactions in dry or aqueous methyl cyanide are shown to involve two transient species, the first of which is an ionic complex formed from a triplet excimer of the arene, or, in the presence of an electron acceptor, from a triplet exciplex. Reaction of the transient complex with the cyanide ion yields the radical ArHCN, and in aqueous methyl cyanide this second transient reacts with itself to produce dihydrocyano- and cyano-compounds. In dry methyl cyanide the radical species is oxidized to the cyano product. 

The standard method of analysis of cyanates involves the acid hydrolysis 6, 19) the kinetics of which have been studied by Amell (jf) ... 

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