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  • acyl
  • Lossen rearrangement, the conversion of a hydroxamic acid to an isocyanate via the formation of an O-acyl, sulfonyl, or phosphoryl intermediate. (wikipedia.org)
  • phosgene
  • Isocyanates are produced by treating amines with phosgene: RNH2 + COCl2 → RNCO + 2 HCl These reactions proceed via the intermediacy of a carbamoyl chloride (RNHC(O)Cl). (wikipedia.org)
  • The first step of the production of MDI is the reaction of aniline and formaldehyde, using hydrochloric acid as a catalyst to produce a mixture of diamine precursors, as well as their corresponding polyamines: Then, these diamines are treated with phosgene to form a mixture of isocyanates, the isomer ratio being determined by the isomeric composition of the diamine. (wikipedia.org)
  • foams
  • Isocyanates react with water to form carbon dioxide: RNCO + H2O → RNH2 + CO2 This reaction is exploited in tandem with the production of polyurethane to give polyurethane foams. (wikipedia.org)
  • Polypropylene polybenzyl isocyanate, or PPI, is a polyurea-based polymer derived from isocyanate monomers that is used in some glues, aerosol foams, plastics, paint and household products. (wikipedia.org)
  • Organic isocyanates are used extensively in the preparation of urethane foams, coatings, and fibers, as well as in the preparation of insecticides, pesticides and the like. (google.com)
  • reactive
  • Isocyanates are electrophiles, and as such they are reactive toward a variety of nucleophiles including alcohols, amines, and even water. (wikipedia.org)
  • 260-47) This invention relates to the protection of reactive isocyanate groups and more particularly this invention relates to a process for protecting reactive isocyanate groups, the novel blocking agents used in said process, and the composition of matter thereby produced. (google.com.au)
  • Free isocyanate groups are known to be quite reactive with water and in particular with the moisture in the air. (google.com.au)
  • When it is later desired to take advantage of the ordinary reactive nature of the isocyanate group, the blocked isocyanate group can be unblocked and again rendered reactive 'by heating to a temperature of about 160 C., thereby unblockin-g the isocyanate group and liberating phenol. (google.com.au)
  • Accordingly, it is an object of this invention to provide a process for blocking reactive isocyanate groups. (google.com.au)
  • Another object is to provide a process for blocking reactive isocyanate groups with a non-volatile, non-toxic, low temperature releasing blocking agent. (google.com.au)
  • amines
  • Isocyanates are common intermediates in the synthesis of primary amines via hydrolysis: Hofmann rearrangement, a reaction in which a primary amide is treated with a strong oxidizer such as sodium hypobromite or lead tetraacetate to form an isocyanate intermediate. (wikipedia.org)
  • Biotage® MP-Isocyanate is a macroporous polystyrene-bound scavenger, which selectively reacts with nucleophiles such as amines and alkoxides. (biotage.com)
  • Biotage® MP-Isocyanate is a macroporous polystyrene-bound scavenger, for nucleophiles such as amines and alkoxides. (biotage.com)
  • Characteristic of other isocyanates, it reacts with amines to give ureas. (wikipedia.org)
  • mixture
  • In this study, we investigated the detection limits and the sensitivity of analysis after the ASSET samplers were spiked with a mixture of DBA-isocyanate derivatives representing an air concentration of 5 µg/m³ at an assumed sample volume of 24 L (recommended flow range of the sampler is 0.1-0.25 L/min). (sigmaaldrich.com)
  • chemical
  • The structure of CSI is represented as ClS(O)2-N=C=O. It consists of two electron-withdrawing components, the chlorosulfonyl group (SO2Cl) and the isocyanate group (-N=C=O). Because of its resulting electrophilicity, the use of CSI in chemical synthesis requires relatively inert solvents such as chlorocarbons, acetonitrile, and ethers. (wikipedia.org)
  • poisonous
  • Methacryloyloxyethyl isocyanate is an extremely poisonous liquid which can be fatal if inhaled, absorbed through skin, or consumed orally. (wikipedia.org)
  • concentration
  • Internal Standards (Deuterated DBA-Isocyanates) are added prior to the extraction to get better quantitation precision and to compensate for any change in the DBA-isocyanate concentration during the extraction process. (sigmaaldrich.com)
  • novel
  • Novel thioether isocyanates and isothiocyanates are produced by the addition of thiols to the olefinic bonds of allyl isocyanates and isothiocyanates. (patentgenius.com)
  • More particularly, this invention relates to the free radical type thiol adducts of allyl isocyanate and isothiocyanate, i.e., 3-substituted thiopropyl isocyanates andisothiocyanates as novel compositions having unexpected properties. (patentgenius.com)
  • hydrogen
  • Since the reaction whereby the isocyanate group is blocked is a reversible one, it would be expected that by using a more volatile material, the blocking agent would be more easily removed from the system and the iso cyanate group could then be reacted with a material hav ing an active hydrogen. (google.com.au)
  • It was believed that if the blocking agents were not removed, then the blocking agents would compete with the material having an active hydrogen for reaction with the free isocyanate groups. (google.com.au)
  • Therefore, volatile materials were generally used as blocking agents both to assure that the blocking agent would not compete with the material containing any active hydrogen for the free isocyanate groups, and to assure a taster release time. (google.com.au)
  • NSF3 reacts with carbonyl fluoride (COF2) in the presence of hydrogen fluoride to form pentafluorosulfanyl isocyanate (SF5NCO). (wikipedia.org)
  • temperature
  • Although, phenol is a satisfactory blocking agent for isocyanates, the use of temperatures of about 160 C. in releasing the isocyanate group from its blocked condition results in an economic disadvantage in the cost of creating and maintaining such a high temperature. (google.com.au)
  • Therefore, the temperature needed to release the blocked isocyanate group is an important consideration in selecting the blocking agent. (google.com.au)