Several methods have been reported for the syn­ thesis of isocyanates, most of them involving the use of phosgene: e.g. phosgene and primary amines [1] either in basic [2] or in acidic medium [1]; phosgene and diaryl urea [1]; phosgene and l-alkyl-3-arylsulphonyl urea [3]; or phosgene and sulfinyl amines [4], Isocyanates were further synthesized from olefins or alkyl halides by the use of isocy...

a simple and mild procedure for the conversion of anilines into aryl isocyanates is described using the 3-hydroxypropylammonium acetate (hpaa) ionic liquid as a novel and efficient media has been explored in the synthesis of aryl isocyanates from the reaction of substituted urea with sodium nitrite in a water immiscible solvent. this ionic liquid can be easily recovered and reused for many time...

[(Salcen)Cr(III) + Lewis base] was found to be a highly active and selective catalyst system in the [2+3] cycloaddition between epoxides and isocyanates to form 5-oxazolidinones. The reaction proceeds to high yield under mild reaction conditions and is applicable to a variety of terminal epoxides and aryl isocyanates.

Polyurethanes are widely used in car paint formulations. During thermal degradation, such polymeric systems can generate powerful asthmatic sensitizing agents named isocyanates. In body repair shops, the thermal degradation of car paint can occur during abrasive processes that generate enough heat to involve release of isocyanates in air. An environmental monitoring study was performed in two b...

BACKGROUND Isocyanates constitute a group of highly reactive, low molecular weight chemicals used worldwide for polyurethane manufacturing. The occupational exposure to these compounds is a major cause of occupational asthma, thus it is very important to monitor their concentration in the workplace atmosphere. The aim of the study was to measure the concentration of 4,4'-methylenediphenyl diiso...

The addition of lithium carbenoids to isocyanates provides a versatile access to N-substituted 2-haloacetamides: the reaction tolerates the presence of variously functionalized substituents on the nitrogen atom, including sterically demanding ones and reactive halogens. No erosion of the enantiopurity was observed in the case of optically active isocyanates. One of the substrates prepared has b...

Carbon-substituted isocyanates and isothiocyanates are common building blocks in organic synthesis. In contrast, synthetic uses of N-substituted isocyanates and isothiocyanates are severely underdeveloped: few have been reported and their reactivity had not been compared. Herein, we compare the reactivity of blocked (masked) N-isocyanate and N-isothiocyanate precursors in cascade reactions. Div...

Investigations of respiratory symptoms among workers in a factory producing polyurethane foam included measurement of air pollution with amines and isocyanates and a simultaneous health investigation of the exposed workers. An increased bronchial reactivity to inhaled methacholine was found in the study group compared with two unexposed control groups. This finding, together with visual disturb...

NIOSH conducted this HHE to investigate complaints from underground coal miners of illnesses, including respirato ry problems, asthma, and skin irritation, after exposure to rock glues in the course of their work duties. NIOSH was requested to provide guidance in establishing a com­ pany medical surveillance program for those workers with exposure to rock glue adhesives containing isocyanates. ...

This study examined the emissions of powerful asthmatic agents called isocyanates from small-scale pyrolysis experiments of two common foams employed in mattress production such as flexible polyurethane foam (FPUF) and viscoelastic memory foam (VMF). A nitrogen atmosphere and five different temperatures, 300, 350, 400, 450 and 850 °C, were selected to carry out the experiments in order to evalu...