Toluene diisocyanate containers

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... 

Biodegradable poly(phosphoester-urethanes) containing bisglycophosphite as the chain extender were synthesized. Methylene bis-4-phenyl isocyanate (MDI) and toluene diisocyanate (TDI) were initially used as diisocyanates. Since there was a concern that the degradation products could be toxic, the ethyl 2,6-diisocyanatohexanoate (LDI) was synthesized and replaced the MDI (or TDI). The hydrolytic stability and solubility of these polymers were tested. Preliminary release studies of 5-fluorouracil from MDI based poly(phosphoester-urethane) and methotrexate from LDI based poly(phosphoester-urethane) are also reported. 

Commonly used isocyanates are toluene diisocyanate, methylene diphenyl isocyanate, and polymeric isocyanates. Polyols used are macroglycols based on either polyester or polyether. The former [polyethylene phthalate) or polyethylene 1,6-hexanedioate)] have hydroxyl groups that are free to react with the isocyanate. Most flexible foam is made from 80/20 toluene diisocyanate (which refers to the ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate). High-resilience foam contains about 80% 80/20 toluene diisocyanate 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. 

Note Reagent grades of 2,4-toluene diisocyanate usually contains minor quantities of the isomer 2,6-toluene diisocyanate. This compound is present in greater concentrations in technical grades. 

We have prepared and characterized three linear isosorbide containing polyurethanes with toluene diisocyanate (TDI), 4,4 -diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HMDI) P(I-TDI), P(I-MDI), and P(I-HMDI). These polyurethanes have been synthesized as described in the experimental section by solution polymerization of isosorbide with the corresponding diisocyanate in dimethylacetamide using dibutyl-tin dilaurate as the catalyst at 75 C for 24 hours. All polymers have been isolated in quantitative yield by precipitation in methanol or water (5). 

Exposure to MOCA was believed to be the cause of urinary frequency and mild hematuria in two of six exposed workers however, a variety of other materials including toluene diisocyanate, polyester resins, polyether resins, and isocyanate-containing resins also were present. ... 

To a flask containing a solution of 8.7 gm (0.05 mole) of 2,4-toluene diisocyanate in 200 ml of anhydrous ether is slowly added a mixture of 0.432 gm (0.024 mole) of water, 50 ml of anhydrous ether, and 0.5 ml of pyridine at room temperature. The urea derivative precipitates as a fine powder, and then 10 ml water is added and the mixture stirred for an additional hr. The product is filtered, washed several times with 1 1 anhydrous petroleum ether-diethyl ether, dried to yield the product, m.p. 172°-175°C (% yield not reported). 

Toluene is a primary feedstock used to produce various organic compounds. It is used to produce diisocyanates. Isocyanates contain the functional group —N = C = O, and diisocyanates contain two of these. The two main diisocyanates are toluene 2,4-diisocyanate and toluene 2,6-diisocyanate. The production of diisocyanates in North America is close to a billion pounds annually. More than 90% of toluene diisocyanate production is used for making polyurethanes foams. The latter are used as flexible fill in furniture, bedding, and cushions. In rigid form it is used for insulation, hard shell coatings, building materials, auto parts, and roller skate wheels. 

A reconstructed ion chromatogram (GC-MS) containing extractable contaminants isolated from a typical lot of foam is shown in Figure 4. The qualitative composition of the extractable contaminants was provided by GC-MS. Contaminant profiles were identical for each of the two solvent systems employed, methylene chloride (1003 ) and ethyl ether/hexane (5/95). The contaminant chemistry shown here and again in Figure 5 in several instances is consistent with the manufacturing process data shown in the box, most notably the presence of residual toluene diisocyanate (starting materials, see Scheme II) and an aliphatic amine (possible reaction catalyst). 

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). 

Moreover, in situ polyurethane formation was performed by irradiation of the polymeric pyridinium salt in THF containing toluene diisocyanate and catalyst. It is clear that alkoxy pyridinium terminated polymers are useful materials as precursors for block copolymers and hydroxy functional telechelics. The latter are particularly attractive in photoinduced polycondensation and in applications where hydroxyl groups are needed to be protected. 

PLURIISOCYANATE. Desmodur L75, provided by Bayer AG, is a 1,1,1-trimethylol propane/toluene diisocyanate adduct containing 25% ethyl acetate by weight. Density 1.17 g/ml NCO equivalent weight per kg 3.06 (by standard titration with di-n-butylamine). Desmodur L75 was used as received. Gel permeation chromatography has shown that this product contains in fact four species of different molecular weights and functionalities (9). 

If the elapsed time between lamination and food contact is too short, imreacted monomeric isocyanate can be available to react with water to form low molecular weight amines. The presence of aromatic amines can be an issue with the use of MDl or toluene diisocyanate (TDl) containing isocyanate systems. Often aromatic isocyanates are selected to obtain good adhesion under moist and low temperature conditions. Aromatic isocyanates are also cheaper than aliphatic systems. The crystallinity of the film can reduce permeation rates of monomeric isocyanates into adjacent film layers. Other factors that can influence the rate/degree of cure (isocyanate reaction) include the following ... 

Wood stains and varnishes used indoors contain aliphatic and aromatic hydrocarbons, isocyanates, ketones, and esters. Though these have limited use compared with paint, newly finished building interiors often contain toxic levels of these. Toluene diisocyanate, used as a catalyst in polyurethane wood finishes, is a powerful respiratory irritant and sensitizer. 13 ... 

Indicative of an all-encompassing approach is the development of the market in depth. The promotion of toluene diisocyanate furnishes an excellent example. The producers of this product as an element in foam have been forced to go all out in developing techniques of fabrication of the finished product, to demonstrate to the ultimate user of foam that systems containing TDI are indeed competitive with and superior to the existing foam (nonchemical) products. The technical service charges which result from such an endeavor loom large. Yet, without them, the chances of success were slim. 

An insoluble polymer containing BINAP 119 was synthesized by polymerization of 6,6 -di(aminomethyl)BINAP 118 with 2,6-toluene diisocyanate (Scheme 55). Ruthenium complexes of this were then screened for activity in... 

Toluene diisocyanate (TDI), methylene diisocyanate (MDI), and related chemicals are industrial components in the poiymerization of urethane coatings and insulation materiais. Most two-part urethane products contain some amount of one of these chemicais, and iesser amounts may oontaminate one-part systems. Methyl isocyanate (the toxin reieased in the Bhopal, India, tragedy) is a carbamate insecticide precursor it is not used in urethanes, has actions different from those of the TDI group of chemicals, and is not discussed here (see Table IV-4, p 593). 

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