• phosgene to form
  • Commercial processes for preparing organic isocyanates utilize the catalytic hydrogenation of an organic nitro compound to form the corresponding amine, followed by reaction of the amine with phosgene to form the corresponding isocyanate. (google.com)
  • 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)
  • 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)
  • reaction
  • No. 3,169,141, issued Feb. 9, 1965, describes a process for separating organic isocyanates from carbodiimides or reaction products containing them by solvent extraction with a liquid organic silane. (google.com)
  • More in detail, any organic carbodiimide, or a complex containing carbodiimide capable of forming an organic isocyanate under the reaction conditions applied may be employed as a reactant in the process of this invention. (google.com)
  • When the isocyanate group is blocked by reaction with phenol, the isocyanate group is protected. (google.com.au)
  • 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)
  • 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)
  • Schmidt reaction, a reaction where a carboxylic acid is treated with ammonia and hydrazoic acid yielding an isocyanate. (wikipedia.org)
  • foams
  • 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)
  • 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)
  • irritants
  • Isocyanates are powerful irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. (webwire.com)
  • Isocyanates are potentially dangerous irritants to the eyes and respiratory tract, despite their relatively low acute toxicities. (wikipedia.org)
  • OSHA
  • Basically, OSHA is now recognizing that using a dry sampler underestimates isocyanate exposures. (bureauveritas.com)
  • The Occupational Safety and Health Administration (OSHA) reports that isocyanates are one of the most common chemical causes of work-related asthma. (webwire.com)
  • synthesis
  • 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)
  • volatile
  • 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)
  • poisonous
  • Methacryloyloxyethyl isocyanate is an extremely poisonous liquid which can be fatal if inhaled, absorbed through skin, or consumed orally. (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)