Toluene diisocyanate reactivity

Toluene diisocyanate Midget impinger 15 ml Marcali solution 1 25 95 Diazotlzation and coupling reaction Materials containing reactive hydrogen attached to oxygen (phenol) certain other diamines... 

Chester E, Martinez-Catinchi EL, Schwartz HI, et al Patterns of airway reactivity to asthma produced by exposure to toluene diisocyanate. Chest 75 229, 1979... 

Luo CJ, Nelson KG, Fishbein A Persistent reactive airway dysfunction s)mdrome after exposure to toluene diisocyanate. Br J Ind Mci 47 239-241, 1990... 

In the reaction of 2,4-toluene diisocyanate the 4-position isocyanate group reacts first and then the one at the 2-position [12]. Some representative examples of the reactivity of diisocyanates with 2-ethylhexanol are shown in Fig. 2. 

Toluene diisocyanates are reactive molecules that combine readily with nucleophiles, and as such have a propensity to react with proteins at the site of application to animals, in other tissues and with plasma (Kennedy et al., 1994). They are hydrolysed in aqueous media to the corresponding diamines, which can react with unchanged toluene diisocyanates to form polymeric ureas (Chadwick Cleveland, 1981 Ulrich, 1983). 

Inhalation exposure of guinea-pigs to toluene diisocyanates (3 h per day on five consecutive days) led to sensitization (antibody formation, pulmonary reactiveness to toluene diisocyanate-albumin conjugate), at exposure levels > 0.14 mg/m (Huang et al., 1993). 

Kennedy, A.L., Wilson, T.R., Stock, M.F., Alarie, Y. Brown, W.E. (1994) Distribution and reactivity of inhaled C-labeled toluene diisocyanate (TDI) in rats. Arch. Toxicol., 68,434-443... 

Diisocyanates or Polyisocyanates. The thiol end groups of the liquid polysulfides are quite reactive with isocyanates (eq. 3). Typical diisocyanates, such as 1,3-toluene diisocyanate (m-TDI) and diphenylmethane-4,4,-diisocyanate (MDI), are effective in curing liquid polysulfides. Using liquid polysulfides in-... 

In addition, Eq. (5.1) should not be applied in systems that exhibit different initial reactivities of functional groups, such as in the copolymerization of double bonds of a particular unsaturated polyester with styrene or in the formation of a polyurethane starting from 2,4-toluene diisocyanate. 

Toluene diisocyanate Diphenylmethane diisocyanate Phthalic anhydride Trimellitic anhydride Platinum salts Reactive dyes... 

LUO, J.D., NELSEN, K.G. FISCHBEIN, A. (1990) Persistent reactive airway dysfunction syndrome after exposure to toluene diisocyanate. British Journal of Industrial Medicine, 47, 239-241. 

A reliable method to determine the oligo-polyol reactivity is the study of the kinetics of the oligo-polyol s reaction with phenyl isocyanate, a model for the -NCO groups of toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI) ... 

Incompatibilities and Reactivities Strong oxidizers, strong acids, toluene diisocyanate, alkalis ... 

I. Mechanism of toxicity. Toluene diisocyanate and related isocyanates act as irritants and sensitizers at very low concentrations. The mechanism is poorly understood, but it is thought that they act as haptens. Once a person is sensitized to one isooyanate, cross-reactivity to others may occur. 

Two types of diisocyanates are employed in polymer preparations aromatic and aliphatic. The most commonly used aromatic diisocyanates are toluene diisocyanate and 4,4 -diphenylmethane diisocyanate. Commercial toluene diisocyanate often comes as a mixture of 2,4 and 2,6 isomers in ratios of 80/20 or 65/35. When the reaction takes place at room temperature, the 4 position is 8 to 10 times more reactive than the 2 position. At elevated temperatures, however, this difference in reactivity decreases, and at 100 °C the reactivity of the isocyanate groups in both positions is approximately equal. 

Isocyanates are used as a cross-linker in EPI adhesive systems. Theoretically, any isocyanate with two or more NCO groups would be suitable. In practice two main parameters are important for the choice of isocyanate The volatility and reactivity of the isocyanate [1, 12]. The use of isocyanates with low volatility, low vapor pressure, is preferred to minimize the health risks concerned with the use and handling of the isocyanate. Isocyanates that are typically used, or have been used, as cross-linkers in EPI adhesive systems are based on the following isocyanate monomers toluene diisocyanate (TDl), diphenylmethane diisocyanate (MDl), hexamethylene diisocyanate (HMDI), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) and triphenylmethane-triisocyanate (TTl)... 

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