Synthesis, Properties and Dimerization Study of Isocyanic Acid

Fischer, Gerd; Geith, Janna; Klapötke, Thomas M.; Krumm, Burkhard

doi:10.1515/znb-2002-0103

Cited by 64 publications

(51 citation statements)

References 14 publications

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“…Thermal decomposition of solid cyanuric acid at 210 • C provides a convenient and relatively clean source of HNCO (Belson and Strachan, 1982), which then diffuses through a capillary (1 mm i.d., 5 cm length) and is mixed with a small flow (50 sccm) of zero air. The system was designed so that the entire capillary was kept at temperature and the gas stream allowed to cool only after mixing to lower concentrations since HNCO is known to polymerize at high concentrations (Fischer et al, 2002). No condensed material was observed in, or downstream of, the mixing volume.…”

Section: Ni-pt-cimsmentioning

confidence: 99%

“…The NCO − ion could arise either from HOCN, cyanic acid, or HNCO, (isocyanic acid). While cyanate salts, such as sodium cyanate (NaOCN), are known to be stable, they evolve HNCO vapor upon acidification (Fischer et al, 2002), and HNCO has been shown to be the most thermodynamically stable of the possible CHNO isomers (Mladenovic and Lewerenz, 2008). There are several studies of the pyrolysis of biomass, coal, and polyamides, that have unambiguously identified HNCO as a major product by infrared spectroscopy (Hansson et al, 2004;Nelson et al, 1996).…”

Section: Isocyanic Acid (Hnco)mentioning

confidence: 99%

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Measurement of HONO, HNCO, and other inorganic acids by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS): application to biomass burning emissions

et al. 2010

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Abstract. A negative-ion proton-transfer chemical ionization mass spectrometric technique (NI-PT-CIMS), using acetate as the reagent ion, was applied to the measurement of volatile inorganic acids of atmospheric interest: hydrochloric (HCl), nitrous (HONO), nitric (HNO 3 ), and isocyanic (HNCO) acids. Gas phase calibrations through the sampling inlet showed the method to be intrinsically sensitive (6-16 cts/pptv), but prone to inlet effects for HNO 3 and HCl. The ion chemistry was found to be insensitive to water vapor concentrations, in agreement with previous studies of carboxylic acids. The inlet equilibration times for HNCO and HONO were 2 to 4 s, allowing for measurement in biomass burning studies. Several potential interferences in HONO measurements were examined: decomposition of HNO 3 ·NO − 3 clusters within the CIMS, and NO 2 -water production on inlet surfaces, and were quite minor (≤1%, 3.3%, respectively). The detection limits of the method were limited by the instrument backgrounds in the ion source and flow tube, and were estimated to range between 16 and 50 pptv (parts per trillion by volume) for a 1 min average. The comparison of HONO measured by CIMS and by in situ FTIR showed good correlation and agreement to within 17%. The method provided rapid and accurate measurements of HNCO and HONO in controlled biomass burning studies, in which both acids were seen to be important products.

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Section: Ni-pt-cimsmentioning

confidence: 99%

Section: Isocyanic Acid (Hnco)mentioning

confidence: 99%

Measurement of HONO, HNCO, and other inorganic acids by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS): application to biomass burning emissions

et al. 2010

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“…5) in aqueous and aqueous-ethanol solutions is possible without catalysis, but proceeds slowly in acidic pH (Aresta et al 2001;Bruno et al 2007;Fischer et al 2002). Consequently, the main ways are the catalytic mechanism described in Eqs.…”

Section: Production Of Ethyl Carbamate In Aqueous and Aqueous-alcoholmentioning

confidence: 99%

Ethyl carbamate in foods and beverages: a review

2008

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Food and beverages contain many toxic chemicals that raise health concerns. Ethyl carbamate (EC) or urethane is the ethyl ester of carbamic acid. It occurs at low level, from ng/L to mg/L, in many fermented foods and beverages. Ethyl carbamate is genotoxic and carcinogenic for a number of species such as mice, rats, hamsters and monkeys. It has been classified as a group 2A carcinogen, ''probably carcinogenic to humans'', by the World Health Organization's International Agency for Research on Cancer (IARC) in 2007. The benchmark dose lower limit of ethyl carbamate is 0.3 mg/kg bw per day and the mean intake of ethyl carbamate from food is approximately 15 ng/kg bw per day. Those levels were calculated for relevant foods including bread, fermented milk products and soy sauce. Alcoholic beverages were not included in this calculation. However, high levels of ethyl carbamate can be found in distillated spirits at concentrations ranging from 0.01 to 12 mg/L depending on to the origin of spirit. Alcoholic drinks should thus be considered as a source of ethyl carbamate. Ethyl carbamate is produced by several chemical mechanisms: first, from urea and various proteins like citrulline produced during the fermentation step and second from cyanide, and hydrocyanic acid, via ethyl carbamate precursors such as cyanate. A large panel of ethyl carbamate formation mechanisms is described from simple ethanolysis of urea in homogeneous liquid phase to photochemical oxidation of cyanide ion or complex heterogeneous gas/solid catalytic reactions. Determination of ethyl carbamate in foods and beverages involves various strategies according to the material, food or beverage, solid or liquid, and according to the concentration, from ng/L to mg/L. Usually, adapted extractive techniques and preconcentration step are followed by analysis by gas chromatography coupled to mass spectrometry (GC-MS of GC-MS-MS). High performance liquid chromatography (HPLC) and semi-quantitative spectroscopic methods (infra-red) are also proposed as valuable alternatives to the classical but time-consuming GC-MS. Various preventing methods are developed and used in some cases at industrial scale to lower ethyl carbamate levels in food. Two types of preventing methods are described. First, adapted and optimised practices in all step of the chain of foods' (or beverages) production lead in general to low ethyl carbamate level. Second, the abatement of ethyl carbamate precursors can be done by adapted enzymatic, physical chemical or chemical methods according to the natures of raw materials and conditions of their production processes.

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“…The reaction of sodium cyanate 3 with an acid (SSA) to produce isocyanic acid 5 could be the first step. 23,37,38 Next, for the generation of the intermediate 7, the proton of SSA is added to isocyanic acid 5 that the proton is perfectly added to nitrogen rather than oxygen. 39 Finally, carbamate 1 is likely to be formed when either alcohol or phenol 2 attack to the carbon of the intermediate 7 (Scheme 3).…”

Section: C-nmr (125 Mhz) the Signals Of Carbonyl Carbon Of Aliphatic Ormentioning

confidence: 99%

Solvent-free preparation of primary carbamates using silica sulfuric acid as an efficient reagent

Modarresi‐Alam¹,

Nasrollahzadeh²,

Khamooshi³

2007

Arkivoc

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A simple and efficient method for the conversion of structurally diverse compounds containing a hydroxyl group to primary carbamates is described by grindstone chemistry. The transformation was done at room temperature with high yield and purity, and without any epimerization in the absence of solvent. Silica sulfuric acid was used as a solid acid and as a mild, convenient and effective reagent for this transformation.

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Synthesis, Properties and Dimerization Study of Isocyanic Acid

Cited by 64 publications

References 14 publications

Measurement of HONO, HNCO, and other inorganic acids by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS): application to biomass burning emissions

Measurement of HONO, HNCO, and other inorganic acids by negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS): application to biomass burning emissions

Ethyl carbamate in foods and beverages: a review

Solvent-free preparation of primary carbamates using silica sulfuric acid as an efficient reagent

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