From isocyanates

Heating trichloromethylcarbonyl isocyanate 18 with a catalytic amount of phenylphospho-lene oxide affords a bis-trichlorocarbonylcarbodiimide 19  

However, heating of phenylcarbonyl isocyanate in the presence of a phospholene oxide catalyst gives 2,6-diphenyl-4-benzoylimino-l,3,5-oxadiazine20.  

The reaction of a-haloisocyanates 21 with N-trimethylsilyl-N -carboxyethylcarbodiimide 22 affords estercarbodiimides 23 with an a-isocyanato group.  

In the reaction of the iminophosphorane 24 with phenyl isocyanate the generated imidoyl-carbodiimide 25 undergoes cyclization to give the tricyclic compound 26.  

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RigidPoly(vinylchloride) Foam. The techniques that have been used to produce rigid vinyl foams are similar to those for the manufacture of flexible PVC foams. The two processes that have reached commercial importance for the manufacture of rigid vinyl foams (246) are the Dynamit-Nobel extmsion process and the Kleber-Colombes Polyplastique process for producing cross-linked grafted PVC foams from isocyanate-modified PVC in a two-stage mol ding process. 

Other functional groups that are easily differentiated are cyanide (5c =110-120) from isocyanide (5c = 135- 150), thiocyanate (5c =110-120) from isothiocyanate (5c = 125 - 140), cyanate (5c = 105- 120) from isocyanate (5c = 120- 135) and aliphatic C atoms which are bonded to different heteroatoms or substituents (Table 2.2). Thus ether-methoxy generally appears between 5c = 55 and 62, ester-methoxy at 5c = 52 N-methyl generally lies between 5c = 30 and 45 and. S-methyl at about 5c = 25. However, methyl signals at 5c = 20 may also arise from methyl groups attached to C=X or C=C double bonds, e.g. as in acetyl, C//j-CO-. 

Calcium hydride, for drying of lert-butyl alcohol, 41, 7 CARBODIIMIDE, DrPHENYL-, 43, 31 Carbodiumdes, from isocyanates, 43, 31... 

Flame retardants in polyurethane foams were determined by SFE-SFC [117]. Off-line SFE-SFC-FID was used for the analysis of additives in polyurethanes [52], and on-line SFE-SFC for extraction of additives from isocyanate formulations [107]. 

When JV /V -carbonyldiimidazole (CDI) is reacted with a primary amine in a 1 1 molar ratio, the product is an imidazole-A-carboxamide. However, these compounds dissociate in solution into isocyanates and imidazole even at room temperature,[1] forming a rapidly equilibrating system. Because of this equilibrium, primary imidazole-A-carboxamides can also be prepared from isocyanates and imidazole. 

Moreover, triuret, ammeline, ammelide, melamine and other products may be formed from isocyanic acid, biuret and combinations of them. If urea is heated up very fast, these reactions are suppressed and the decomposition into ammonia and isocyanic acid is the preferred reaction. Due to the high reactivity of isocyanic acid, its primary formation may subsequently lead to the formation of the aforementioned compounds of higher molecular weight. In order to avoid the formation of by-products, the heating-up must be carried out fast. Only then ammonia and isocyanic acid are obtained as sole products. In any case, local undercooling of the gas duct should be avoided and rapid dilution of the thermolysis products in the exhaust gas has to be ensured in order to avoid locally high concentrations of reactive compounds. 

Examples of non-urethane linkages derived from isocyanates a) urea, b) urea, c) biuret, d) amide, and e) allophanate... 

More recently, Belzner et al. reported a new type of oxygen transfer reaction from isocyanates to bis[2-(dimethylaminomethyl)phenyl]silylene (8)18 which was thermally generated from the corresponding cyclotrisilane 7, and they obtained some convincing results of the involvement of silanone 9 (Scheme 3). However, they found that silanone 9 is not stable enough to be isolated. Only cyclic di- and trisiloxanes 10 and 11 (i.e., the cyclic dimer and trimer of the silanone 9) were obtained together with the corresponding isonitrile as other main products when... 

Wisnewski, A.V. et al., Glutathione protects human airway proteins and epithelial cells from isocyanates, Clin Exp Allergy, 35, 352, 2005. 

Carbodiimide, diphenyl-, 43,31 Carbodiimides, from isocyanates, 43, 31 Carboxylation of saturated hydrocarbons containing tertiary hydrogens, 44, 3... 

In the future it might be possible to see the gas diffusion technology generating chlorine with energy consumption at 1500 kWh. The chlorine will be used in the direct chlorination of ethane to feed the vinyl chain. Side streams of HC1 will be used in oxychlorination where ethylene is available and this will use up by-product acid from isocyanates. Site integration will increase to benefit from economies of scale and optimise hydrogen chloride production. 

Sodium perborate in acetic acid converts oximes into nitro compounds thus acetophenone oxime yields 52% of PhCHMeN02403. Nitroalkanes and nitroarenes are obtained from isocyanates and dimethyldioxirane (equation 122)404. 

The first publications to describe the phosphane oxide-catalyzed carbodi-imide synthesis from isocyanate appeared in 1962. In this case iminophos-phoranes were recognized as important intermediates. The first mechanistic studies also appeared at this time. Scheme 24 depicts the proposed two-step mechanism (62JA3673, 62JA4288 66CJC2793). 

Belin L, Wass U, Audunsson G, et al Amines Possible causative agents in the development of bronchial hyperreactivity in workers manufacturing polyurethanes from isocyanates. BrJ Ind Med 40 251-257, 1983... 

Another procedure for preparation of allophanyl chlorides from isocyanates and subsequent cyclization in 35-95% yield to uretidinediones has also been reported (70AG(E)372). 

Prolonged heating of free isocyanates in the absence of catalysts has been reported recently to give poor yields of carbodiimides unless a slow stream of nitrogen was passed through the boiling isocyanate [18]. In the presence of phosphorus catalysts [18, 19, 27-39], aromatic carbodiimides are obtained in high yield under mild conditions from isocyanates but not isothiocyanates [18]. Aliphatic isocyanates react more slowly, but improved yields are obtained in... 

Trimerization of imidates is a valuable route to 1,3,5-triazines. Imidates can be considered as activated nitriles and cyclotrimerize more readily. Most symmetrical 2,4,6-trialkyl-1,3,5-triazines are easily formed, although large alkyl substituents may give rise to steric hindrance (61JOC2778). Symmetrical isocyanurates (525) are readily available from isocyanates, RNCO catalysts include tertiary amines, phosphines and sodium methoxide. Aldehydes RCHO and ammonia give hexahydro-1,3,5-triazines (526), known as aldehyde ammonias (73JOC3288). 

Symmetrical isocyanurates are readily synthesized from isocyanates in the presence of a variety of catalysts including tertiary amines, phosphines, sodium acetate and sodium methoxide in anhydrous conditions. The method has been reviewed thoroughly (B-71MI22002,... 

The preparation of a variety of isocyanurates from isocyanates is summarized in Table 16. 

Table 16 Synthesis of Symmetrical Isocyanurates from Isocyanates (RNCO)...

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