Cyanates, detection

Calcium carbide Nitrogen cyanate detection Dibenzylamine cyanide detection o-Aminophthalyl hydrazide cyanide mfg. 

Acetate kinase is phosphorylated by acetyl phosphate and it has been shown that the phosphoenzyme can synthesise ATP from ADP, and acetyl phosphate from acetate. The mode of decomposition of carbamyl phosphate in aqueous solution is pH dependent and can proceed with either the production of ammonia and carbon dioxide (equation 1), or cyanate (equation 2). No cyanate could be detected during the hydrolysis... 

It is not clear whether the conditions used in the above experiments correspond to those present on the young Earth. Cyanate has been detected in cosmic nebulae (Yamagata, 1999), while water-soluble phosphates and diphosphates can be formed during volcanic activity, as Yamagata showed as early as 1991 (see Sect. 4.7.3). 

The chiral amines (55) were first derivatized by conventional reaction with fluorescene-isothio-cyanate (57) leading to fluorescein-active compounds (58) (Equation (9)) that enable a sensitive detection system, specifically laser-induced fluorescence detection (LIF), to be used.90 Although... 

Low detection limits (low ng/mL) have been achieved using a headspace/gas chromatographic (GC) technique (Seto et al. 1993). The sample is acidified and incubated, and the headspace analyzed by GC with a nitrogen-specific detector (NPD) (Carseal et al. 1993 Levin et al. 1990 Seto et al. 1993). Reported recovery is good (>90%) (Carseal et al. 1993), and precision is good as well (<15% RSD) (Carseal et al. 1993 Levin et al. 1990 Seto et al. 1993). Blood samples may be treated with chloramine T priorto incubation to produce a derivative which can be determined by GC with electron capture detection (ECD). Cyanate and thiocyanate do not interfere in this method (Odoul et al. 1994). The detection limit is 5 pg/L (ppb) precision is good (<15% RSD) (Odoul et al. 1994). 

No reaction of excited 1-nitroazulene with hydroxide and cyanate ions or p nidine could be detected... 

Fig. 1. Simultaneous separation and detection of anions and cations on a latex agglomerate column. Column Dionex HPIC-CS5 cation exchange column (250X2 mm) with precolumn HPIC-CG5 (50 X 4 mm) eluent 0.5 mM copper sulfate, pH 5. 62 flow rate 0.5 ml/min sample volume 20 gl containing 0.1 m M of each ion detection two potentiomet-ric detectors equipped with different ion-selective electrodes in series. Peaks (1) chloroacetate, (2) chloride, (3) nitrite, (4) benzoate, (5) cyanate, (6) bromide, (7) nitrate, (8) sodium, (9) ammonium, (10) potassium, (11) rubidium, (12) cesium, (13) thallium. Reprinted with permission from [10].

However, this reaction requires relatively high concentrations of cyanate (> 0.1 M), unlikely to occur in aqueous media given its rapid degradation to carbon dioxide and ammonia. In order to optimize the yield of cytosine by this procedure, cyano acetylene 15 was treated with a lower amount of cyanate at 100 °C. Under these more efficient experimental conditions cytosine was obtained in 19% overall yield along with a low amount of uracil [79]. An alternative route explored consists of the use of urea 19, which is considered a common prebiotic precursor [80], as one-carbon atom donor in the place of cyanate. The reaction of cyano acetylene 15 (1.0 M) with 19 (1.0 M) at 100 °C gave cytosine 17 in 5% yield (Scheme 11). At low concentrations of 19 (< 0.1 M) this reaction does not produce detectable amounts of cytosine [81]. 

The blue complex is stable in the presence of a moderate excess of acetic acid the reaction can therefore be applied to the detection of cyanates in alkaline solution. The solution to be tested is added to the copper-pyridine-chloroform mixture, acetic acid added slowly and the solution shaken vigorously after each addition. As soon as the solution is neutral, the chloroform will assume a blue colour. 

Aharoni has reported experiments on the system tetrachloroethane/polyiso-cyanate (POIC)/polystyrene that confirm the foregoing predictions. The nematic phase separates at compositions in the range predicted polystyrene does not occur in detectable quantities in this phase. The binodal for the isotropic phase resembles the calculated curve shown in Fig. 6. 

CS is absorbed very rapidly from the respiratory tract, and the half-lives of CS and its principal bioconversion products are reported to be extremely short. The disappearance of CS follows first-order kinetics over the dose range examined. CS spontaneously hydrolyzes to malononitrile, and the latter is transformed to cyanide in animal tissues. Metabolically, CS undergoes conversion to 2-chlorobenzyl mal-ononitrile (CSHj), 2-chlorobenzaldehyde (oCB), 2-chlorohippuric acid, and thio-cyanate. " CS and its metabolites can be detected in the blood after inhalation exposure, but only after large inhalation doses. Following inhalation exposure of rodent and non-rodent species to CS aerosol, CS and two of its metabolites... 

The triple bonded organic functional groups considered in the present chapter are —CC—, —CN, —CNO (nitrile oxide), —OCN, —SCN and —N2. Some isomeric functions such as —NC, —NCO and —NCS, will also be included, as they sometimes occur together with their isomers. The general aspects and specific methods for the analysis of alkynes, nitriles, diazonium compounds, cyanates and thiocyanates, and other related functional groups were adequately described in previous books of the series The Chemistry of Functional Groups, Consideration was made there of detection and determination by means of chemical reactions and application of characteristic spectroscopic properties of the groups. 

Separations on cyanogen bromide-activated polysaccharide resins (Sepharose, Sephadex) yield imidocarbamates and cyanates. The former are determined after selective liberation of ammonia and a modification of the ninhydrin reaction. Organic cyanates can be detected and determined spectrophotometrically in nanomolar quantities, by treatment with a reagent consisting of pyridine and dimethylbarbituric acid (23) as depicted in reactions 34 and 35 d58 ... 

---