Chemical toluene diisocyanate

Materials and Purification. Chemicals were purchased from Aldrich chemical company and used as received unless otherwise noted 1,1,1,3,3,3-hexamethyl disilazane, ethylene glycol, triphosgene, poly(ethylene oxide) (MW = 600), poly(tetramethylene oxide) (MW = 1000), poly(caprolactonediol) (MW = 530), toluene diisocyanate (TDI), anhydrous ethanol (Barker Analyzed), L-lysine monohydride (Sigma) and methylene bis-4-phenyl isocyanate (MDI) (Kodak). Ethyl ether (Barker Analyzer), triethylamine and dimethyl acetamide were respectively dried with sodium, calcium hydride and barium oxide overnight, and then distilled. Thionyl chloride and diethylphosphite were distilled before use. 

Certain LMW agents will cause OA via a poorly defined mechanism. Only about 20% of workers with OA to toluene diisocyanate (TDI) have IgE detectable to TDI indicating that IgE antibody may be more an indicator of exposure rather than a mediator of the disease [10], Similar data exist for workers with asthma caused by plicatic acid from western red cedar [11], The inability to detect IgE antibody in the majority of these workers may be based in technical issues such as the nature of the chemical-protein... 

Uses/Sources. Intermediate in organic synthesis, especially production of toluene diisocyanate and polymethylene poly-phenylisocyanate in metallurgy to separate ores by chlorination of the oxides and volatilization occurs as a product of combustion whenever a volatile chlorine compound comes in contact with a flame or very hot metal originally manufactured as an agent for chemical warfare during World War I... 

We have already been introduced to polyurethane chemistry in Chapter 10, Section 2, where we used toluene diisocyanate (TDI) reacting with a diol to give a polyurethane. Polyurethanes derived from MDI are more rigid than those from TDI. New applications for these rigid foams are in home insulation and exterior autobody parts. The intermediate MDA is now on the Reasonably Anticipated to Be Human Carcinogens list and the effect of this action on the market for MDI remains to be seen. The TLV-TWA values for MDA and MDI are some of the lowest of the chemicals we have discussed, being 0.1 and 0.005 ppm respectively. 

The average prices of commercial quantities in cents per pound are given in Table 13.1. Six chemicals are over 1.00/lb hexamethylenediamine (59), methylene diphenyl diisocyanate (68), toluene diisocyanate (78), phosphorus (86), 1,4-butanediol (89), and potassium hydroxide (90). In 1992 only three chemicals, and in 1988 only two chemicals, were over 1.00/lb. The cheapest of the second 50 chemicals is tall oil, with sodium sulfate close. The average price for all the second 50 chemicals is 0.55/lb. 

Phosgene is a key intermediate used in synthesis of many chemicals, a major one being toluene diisocyanate, a monomer in polyurethanes. Phosgene is made from chlorine and carbon monoxide through the overall reaction... 

There is a large body of information available in the open literature on the toxicological and occupational hazards of diisocyanate compounds (particularly on toluene diisocyanate) however, relatively little information is available specifically for HDl or HDl polymers. It would be convenient to be able to use the available data on other diisocyanates, such as toluene diisocyanate, to extrapolate any missing information on HDl toxieity however, fundamental differences in chemical properties and metabolism have precluded that possibility. 

Toluene diisocyanates are industrial chemicals produced in large volumes. Exposure... 

WHO (1987) Toluene Diisocyanates (Environmental Health Criteria 75), Geneva, International Programme on Chemical Safety... 

By March 1, 1957, the ami noethylation of the following materials and compds had been achieved by the Wyandotte Chemicals Corp cellulose, cellulose derivatives, regenerated c e 1 lu los e, 2-hydroxymethy 1-2-nitro-1,3-pro-panediol, nylon, polyurethane, polyvinyl alcohol, polyvinylchloride, protein(wool), starch and toluene diisocyanate... 

Amberlite XAD-2 and XAD-4 resins, for example, contain significant quantities of alkyl derivatives of benzene, styrene, naphthalene, and biphenyl as received from the supplier. PUF products, on the other hand, generally contain numerous contaminants peculiar to one of the several patented commercial manufacturing processes. These include, but are not limited to, the following classes of chemical contaminants isocyanate derivatives (e.g., toluene diisocyanates), alkyl amines, aliphatic acids, and brominated aromatics (e.g., fire retardants). 

Fig. 21. Mooney-Rivlin plots (Eq. IV-1) for a chemically crosslinked polyurethane rubber (from polyoxypropyleneglycol, toluene diisocyanate and trimethylol propane). Note the differences in Cx and C2 values in extension and compression...

Irritant dermatitis does not involve an immune response and is typically caused by contact with corrosive substances that exhibit extremes of pH, oxidizing capability, dehydrating action, or tendency to dissolve skin lipids. In extreme cases of exposure, skin cells are destroyed and a permanent scar results. This condition is known as a chemical burn. Exposure to concentrated sulfuric acid, which exhibits extreme acidity, or to concentrated nitric acid, which denatures skin protein, can cause bad chemical bums. The strong oxidant action of 30% hydrogen peroxide likewise causes a chemical bum. Other chemicals causing chemical bums include ammonia, quicklime (CaO), chlorine, ethylene oxide, hydrogen halides, methyl bromide, nitrogen oxides, elemental white phosporous, phenol, alkali metal hydroxides (NaOH, KOH), and toluene diisocyanate. 

A second method of achieving latency is by using a curative precursor, which is chemically inactive at room temperature but then converts to an active curative at the cure temperature. Examples of this type include Monuron and di-urea adduct of toluene diisocyanate and dimethylamine. Full cure in about 1 h at 125°C is achievable with these materials. 

International Program on Chemical Safety and the Commission of the European Communities (IPCS-CEC). 1995. 2,4-Toluene diisocyanate, card no. 0339 (updated 2004). Geneva, Switzerland International Labor Organization. 

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