Methylene diphenyl diisocyanate MDI

Similarly, nitroben2ene, carbon monoxide, and methanol can react sequentially in the presence of noble metal catalysts, to produce methyl A/-phenylcarbamate [2603-10-3] (4). The phenylcarbamate is subsequently coupled with formaldehyde [50-00-0] to yield the methylenebis(carbamate) (5) which is pyroly2ed to yield methylene diphenyl diisocyanate (MDI) (23). 

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. 

Maleamic acid, cyclization of, 293 Maleic anhydride, 59 Maleimido azine, 307 Manganese diacetate catalysts, 71 Mark-Houwink-Sakurada equation, 57 Material safety data sheets (MSDSs), 246 Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), 385, 388 McGrath, J. E., 327 MDI isomers, 210 MDIs. See Methylene diphenyl diisocyanates (MDIs)... 

Methylene diphenyl diisocyanates (MDIs), 201, 219. See also MDI isomers liquefied, 211, 226-227 Methyl placement, precise versus random, 447... 

Phenolic-isocyanates (phenolic-urethanes). The binder is supplied in three parts a phenolic resin in an organic solvent (0.8%), methylene diphenyl diisocyanate (MDI) (0.5%), and a liquid amine catalyst. When mixed with sand, the amine causes a reaction between the resin and the MDI, forming urethane bonds, which rapidly set the mixture. The speed of setting is controlled by the type of catalyst. The optimum cure temperature is 25 to 30°C. Compression strength is typically over 4000kPa (600psi). 

Uses. Production of methylene diphenyl diisocyanate (MDI), which is used to produce polyurethanes hardening agent for epoxy resins, anticorrosive materials, printed circuit parts, dyestuff intermediates, filament-wound pipe, and wire coatings... 

The uses of aniline obtained from nitrobenzene are given in Table 11.5. Aniline s use in the rubber industry is in the manufacture of various vulcanization accelerators and age resistors. By far the most important and growing use for aniline is in the manufacture of jP,jP-methylene diphenyl diisocyanate (MDI), which is polymerized with a diol to give a polyurethane. 

Major uses of aniline include -methylene diphenyl diisocyanate (MDI) (75%) and rubber chemicals (15%) production. It is also used to a smaller extent in herbicides (4%), dyes and pigments (3%), and specialty fibers (2%). 

A synthetic approach to poly(ester-urethanes) was recently published by Xue et al. [48]. Glycerol was employed as a trifunctional initiator in the enzymatic ROP of CL. The three-arm PCL triol was then reacted with methylene-diphenyl diisocyanate (MDI) and hexanediol to yield a three-arm PCL-based poly(ester-urethane) with shape-memory properties. 

Important commercial isocyanates include the diisocyanate monomers toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and MDI-, TDI-, and HDI-based isocyanates (e.g., prepolymers and polyisocyanates). World-wide production volume is estimated at over 12 billion lb. Isocyanates (diisocyanates, polyisocyanates, and prepolymers) all cause similar health effects, most commonly asthma [32]. Isocyanates are reported to be the leading attributable cause of work-related asthma [16]. Isocyanates are potent sensitizers that can trigger a severe and potentially fatal asthma attack in sensitized persons at very low isocyanate exposure levels [16]. Toluene diisocyanate is reasonably anticipated to be a human carcinogen by National Toxicology Program. 

Processes are under development to manufacture methylene diphenyl diisocyanate (MDI) without using toxic and corrosive phosgene. The proposed process schemes usually consist of three steps alkoxycarbonylation of nitrobenzene or aniline with CO and an alcohol to alkyl plienylcarbamate, condensation of the carbamate, and then thermal decomposition of the resulting urethane to MDI. For example, the condensation of methyl N—phcnylcarbamate (MPC), and IICHO into methylene diphenyl diurethane (MDU) is carried out in the presence of an acid catalyst. 

Isocyanates (RNCO) are industrially relevant compounds which find application in several fields [9, 106]. Many isocyanates serve as the starting materials for the manufacture of plant protection agents, pesticides, dyes, resins and plastics, textile waterproofing agents, detergents, bleaches, and adhesives. They are also widely used in surface coatings such as paints, sealants and finishes, and in the manufacture of rubbery plastics such as those used to coat wires. Traditionally, diisocyanates are the primary feedstock for the production of polyurethanes. The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate... 

Methylene diphenyl diisocyanate (MDI) is produced by the condensation of aniline with formaldehyde followed by reaction with phosgene. 

Nitrobenzene Nitrobenzene is made by the direct nitration of benzene with nitric/sulfuric acid mixtures primarily for aniline production. And aniline is a raw material for the manufacture of methylene diphenyl diisocyanate (MDI) that is used to make rigid foams. 

The design of the anchors totally depends on the proposed mechanism of SMA-matrix material incorporation. In this study, 4,4 -methylene diphenyl diisocyanate (MDI) is applied as the localizing anchor that physically bonds to the PEU matrix material by mimicking the physical crosslink between PEU hard blocks. Finally, the ABCBA -type SMA, named MPEO , is constructed as shown in Fig. 1, in which A represents bio-functional endgroups, B represents the PEG spacer, and C represents the MDI anchor that also plays the role of coupling groups for A-B moieties on both sides [76,77]. 

Aniline is consumed as a raw material in the manufacture of a number of chemicals /7,/7-methylene diphenyl diisocyanate (MDI), 65 percent rubber-processing chemicals, 15 percent herbicides, 5 percent dyes and pigments, 4 percent specialty fibers, 2 percent. Other uses are in pharmaceuticals and photo chemicals. Principal growth is occurring from demand for MDI and the small, rapidly growing specialty fibers. 

U.S. Environmental Protection Agency, Toxicological Review of Methylene Diphenyl Diisocyanate (MDI), 1999. 

This process was elaborated as a heterogeneously catalyzed variation by Asahi Chemicals (Japan) in order to open a new route to diisocyanates, not depending on the use of phosgene [120, 134]. Ethyl phenylcarbamate, which in a first step is obtained by catalytic oxidative carbonylation of aniline, CO, oxygen, and ethanol (eq. (17)), is condensed with aqueous formaldehyde to yield methylene diphenyl diurethane. Thermal decomposition leads to methylene diphenyl diisocyanate (MDI), which is one of the most important intermediates for the industrial manufacture of polyurethanes (eq. (18)). The yields and selectivities of the last reaction step seem to be the main reasons why this process is still inferior to the existing ones. 

There are regulatory and handling problems in using methylene bis(2-chloroaniline) as a chain extender (curative or cross-linker) for toluene diisocyanate (TDI)-terminated prepolymers, to produce urethane elastomers (1,2). There is, therefore, a strong interest in achieving similar elastomer properties with other curatives and methylene diphenyl diisocyanate (MDI)-terminated prepolymers(3,4). 

All chemicals used in this study were reagent grade. Butyl isocyanate (BuNCO, 99% from the Upjohn Chemical Co.), hexamethy-lene diisocyanate (HDI, 99% from the Mobay Chemical Co.), phenyl isocyanate (PhNCO, 99%, from the Upjohn Chemical Co.), p-tolyl isocyanate (MePhNCO, 99% from the Aldrich Chmical Co.), p-chloro-phenyl isocyanate (CIPhNCO, 99%, from the Aldrich Chemical Co.) and cyclohexyl isocyanate (CHI, 98%, from the Aldrich Chemical Co.) were purified by vacuum distillation. Methylene diphenyl diisocyanate (MDI, 99%+, from the Mobay Chemical Co.) was used without further purification. N,N-Dimethylformamide (DMF, reagent grade, from the Mallinckrodt) was dried by molecular sieves 4a. The NCO-terminated prepolymers were prepared from poly(oxy-tetramethylenediol) (POTMD, mol. wt. 650, 1000, 2000, Quaker Oats Chem. Co.) and MDI. 

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