Toluene isocyanates

Side-chain photochlorination of toluene isocyanates yields important industrial intermediates for polyurethane synthesis, one of the most important classes of polymers [6]. The motivation for micro-channel processing stems mainly from enhancing the performance of the photo process. Illuminated thin liquid layers should have much higher photon efficiency (quantum yield) than given for conventional processing. In turn, this may lead to the use of low-intensity light sources and considerably decrease the energy consumption for a photolytic process [6] (see also [21]). 

Side-chain photochlorination of toluene isocyanates leads to important industrial intermediates for polyurethane synthesis, one of the most important classes of polymers [264]. Irradiated thin liquid layers in microchannels should have much higher photon efficiency (quantum yield) than given for conventional processing. 

SYNS BENZENE, l-ISOCYANATO-2-METHYL- ISOCYANIC ACID, o-TOLYL ESTER o-METHYL-PHENYL ISOCYANATE 2-METHYLPHENYL ISOCYANATE o-TOLUENE ISOCYANATE o-TOLYL ISOCYANATE 2-TOLYL ISOCYANATE... 

TOLUENE DIISOCYANATE see TGM800 TOLUENE, ar,ar-DINITRO- see DVG600 2,3-TOLUENEDIOL see DNEOOO TOLUENE HEXAHYDRIDE see MIQ740 o-TOLUENE ISOCYANATE see IKG725 TOLUENE-2-SULFONAMIDE see TGN250... 

Nitroxyl radicals can also be used to improve the mechanical properties of filled polymers, resins in particular, by increasing the adhesive quality of the fillers by treating their surfaces with solutions of nitroxyl radicals. The efficiency of nitroxyl radicals as modifiers is higher than that of well-known modifiers e.g., 4-toluene isocyanate. 

The most conunonly used cross-linkers for CS membranes are epichlorohydrin (ECH) and glutaraldehyde (GA, Rgure 16.11). In literature, one can also find the other cross-linkers like toluene isocyanate and sodium tripolyphosphate (TPP). Most recently, Mio et al. [55] prepared amphoteric thin film NF membrane using sulfated CS as the active layer on to the surface of PSf UF support followed by cross-linking using ECH. The membranes were tested for salt rejection application. The membranes showed a maximum of 90.8% Na2S04 (with 22.9 kg h permeate flux) and 32.5% NaCl (with 58.4 kg-2 h- permeate flux) rejection, respectively, at 0.4 MPa pressure for 1000 mg/L feed concentrations. Thus, they concluded that the resultant cross-linked SCS/PSf membranes... 

Toluene hexahydride. See Methyl cyclohexane 4-Toluene isocyanate. See p-Tolyl isocyanate m-Toluene isocyanate. See m-Tolyl isocyanate o-Toluene isocyanate. See o-Tolyl isocyanate p-Toluene isocyanate. See p-Tolyl isocyanate Toluene, a-phenyl-. See Diphenylmethane p-Toluenesulfamine 4-Toluenesulfanamide p-Toluenesulfanamide. See p-Toluenesulfonamide p-Toluenesulfinic acid, sodium salt. See Sodium p-toluenesulfinate p-Toluenesulfochloride. See p-Toluenesulfonyl chloride... 

Synonyms 1 -lsocyanato-3-methylbenzene Isocyanic acid, m-tolyl ester 3-Methylphenyl isocyanate m-TMl m-Toluene isocyanate 3-Tolyl isocyanate... 

Synonyms 1 -lsocyanato-2-methylbenzene Isocyanic acid, o-tolyl ester 2-Methyl phenyl isocyanate o-TMl o-Toluene isocyanate... 

CAS 622-58-2 EINECS/ELINCS 210-743-4 Synonyms Benzene, 1-isocyanato-4-methyl- 1-lsocyanato-4-methylbenzene 4-Isocyanatotoluene p-lsocyanatotoluene Isocyanic acid, p-tolyl ester 4-Methylphenyl isocyanate p-M ethyl phenyl isocyanate TMI p-TMl 4-Toluene isocyanate p-Toluene isocyanate 4-Tolyl isocyanate Classification Isocyanic acid ester Empirical CsHyNO... 

Commonly used isocyanates are toluene dhsocyanate, methylene diphenyl isocyanate, and polymeric isocyanates. Polyols used are macroglycols based on either polyester or polyether. The former [poly(ethylene phthalate) or poly(ethylene 1,6-hexanedioate)] have hydroxyl groups that are free to react with the isocyanate. Most flexible foam is made from 80/20 toluene dhsocyanate (which refers to the ratio of 2,4-toluene dhsocyanate to 2,6-toluene dhsocyanate). High-resilience foam contains about 80% 80/20 toluene dhsocyanate and 20% poly(methylene diphenyl isocyanate), while semi-flexible foam is almost always 100% poly(methylene diphenyl isocyanate). Much of the latter reacts by trimerization to form isocyanurate rings. 

Both dimethyl carbonate [616-38-6] and diphenyl carbonate [102-09-0] have been used, in place of carbon monoxide, as reagents for the conversion of amines into isocyanates via this route (28,29). Alternatively, aniline [62-53-3] toluene diamines (I JJA), and methylene dianilines (MDA) have also been used as starting materials in the carbonylations to provide a wide variety of isocyanate monomers. 

More recently, a commercial process has been introduced for the manufacture of methyl isocyanate (MIC) which involves the dehydrogenation of /V-m ethyl form am i de [123-39-7] in the presence of palladium, platinum [7440-06-4], or mthenium [7440-18-8], at temperatures between 50—300°C (31). Aprotic solvents, such as ben2ene [71-43-2], xylenes, or toluene [108-88-3], may optionally be used. A variation of this synthesis employs stoichiometric amounts of palladium chloride [7647-10-1], PdCl2. 

For methylene diphenyl diisocyanate (MDI), the initial reaction involves the condensation of aniline [62-53-3] (21) with formaldehyde [50-00-0] to yield a mixture of oligomeric amines (22, where n = 1, 2, 3...). For toluene diisocyanate, amine monomers are prepared by the nitration (qv) of toluene [108-88-3] and subsequent hydrogenation (see Amines byreduction). These materials are converted to the isocyanate, in the majority of the commercial aromatic isocyanate phosgenation processes, using a two-step approach. 

Attempts have been made to develop methods for the production of aromatic isocyanates without the use of phosgene. None of these processes is currently in commercial use. Processes based on the reaction of carbon monoxide with aromatic nitro compounds have been examined extensively (23,27,76). The reductive carbonylation of 2,4-dinitrotoluene [121 -14-2] to toluene 2,4-diaLkylcarbamates is reported to occur in high yield at reaction temperatures of 140—180°C under 6900 kPa (1000 psi) of carbon monoxide. The resultant carbamate product distribution is noted to be a strong function of the alcohol used. Mitsui-Toatsu and Arco have disclosed a two-step reductive carbonylation process based on a cost effective selenium catalyst (22,23). 

A convenient method for the synthesis of these low boiling materials consists of the reaction of /V,/V-dimethy1iirea [96-31-1] with toluene diisocyanate to yield an aUphatic—aromatic urea (84). Alternatively, an appropriate aUphatic—aromatic urea can be prepared by the reaction of diphenylcarbamoyl chloride [83-01-2] with methylamine. Thermolysis of either of the mixed ureas produces methyl isocyanate ia high yield (3,85). 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

Diisocyanates or Polyisocyanates. The thiol end groups of the hquid polysulfides are quite reactive with isocyanates (eq. 3). Typical chisocyanates, such as 1,3-toluene chisocyanate (m-TDl) and diphenylmethane-4,4 -diisocyanate (MDl), ate effective in curing hquid polysulfides. Using hquid polysulfides in-... 

Ammonia is used in the fibers and plastic industry as the source of nitrogen for the production of caprolactam, the monomer for nylon 6. Oxidation of propylene with ammonia gives acrylonitrile (qv), used for the manufacture of acryHc fibers, resins, and elastomers. Hexamethylenetetramine (HMTA), produced from ammonia and formaldehyde, is used in the manufacture of phenoHc thermosetting resins (see Phenolic resins). Toluene 2,4-cHisocyanate (TDI), employed in the production of polyurethane foam, indirectly consumes ammonia because nitric acid is a raw material in the TDI manufacturing process (see Amines Isocyanates). Urea, which is produced from ammonia, is used in the manufacture of urea—formaldehyde synthetic resins (see Amino resins). Melamine is produced by polymerization of dicyanodiamine and high pressure, high temperature pyrolysis of urea, both in the presence of ammonia (see Cyanamides). 

Isocyanates. The commodity isocyanates TDI and PMDI ate most widely used in the manufacture of urethane polymers (see also Isocyanates, organic). The former is an 80 20 mixture of 2,4- and 2,6-isomers, respectively the latter a polymeric isocyanate obtained by phosgenation of aniline—formaldehyde-derived polyamines. A coproduct in the manufacture of PMDI is 4,4 -methylenebis(phenyHsocyanate) (MDI). A 65 35 mixture of 2,4- and 2,6-TDI, pure 2,4-TDI and MDI enriched in the 2,4 -isomer are also available. The manufacture of TDI involves the dinitration of toluene, catalytic hydrogenation to the diamines, and phosgenation. Separation of the undesired 2,3-isomer is necessary because its presence interferes with polymerization (13). 

An equimolar mixture of carbon monoxide and chlorine reacts at 500 K under a slight positive pressure. The reaction is extremely exothermic (Ai/gQQp. = —109.7 kJ or —26.22 kcal), and heat removal is the limiting factor in reactor design. Phosgene (qv) is often produced on-site for use in the manufacture of toluene diisocyanate (see Amines, aromatic-diaminotoluenes Isocyanates, organic). 

Type AD-G is used in an entirely different sort of formulation. The polymer is designed for graft polymerisation with methyl methacrylate. Typically, equal amounts of AD-G and methyl methacrylate are dissolved together in toluene, and the reaction driven to completion with a free-radical catalyst, such as bensoyl peroxide. The graft polymer is usually mixed with an isocyanate just prior to use. It is not normally compounded with resin. The resulting adhesive has very good adhesion to plasticised vinyl, EVA sponge, thermoplastic mbber, and other difficult to bond substrates, and is of particular importance to the shoe industry (42,43). 

Nitrophenyl isocyanate has been prepared by heating -nitrophenyl carbamyl chloride. The latter has been obtained by the action of phosgene on -nitroaniline in benzene-toluene solutions, and by the action of phosphorus pentachloride on methyl jii-nitrophenylcarbamate. The preparation given above is based upon recent publications of the authors. ... 

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