Heat-sensitive reactive products

Eastman Kodak Co. Heat sensitive reactive products of hexaarylbiimidazole and antihalation dyes... 

Reactive and heat-sensitive components must be removed early to avoid problems of product degradation. 

The residence time characteristics in an extruder have a great influence on product quality, for instance when processing heat-sensitive products, in reactive processes, and in the case of dispersion and melting. As with all continuous processes, there is no precisely defined residence time in co-rotating twin screw extruders, but rather a residence time distribution. 

HFCVD is performed by placing a heated filament or wire above the substrate. Precursor molecules are pyrolyzed above the wire, and reactive intermediates or products adsorb to the deposition surface. This technique is advantageous because the substrate can be kept at a lower temperature, since the heated filament provides the necessary energy for cracking the precursor molecules. As a result, high temperature reactions can still be used to deposit refractories on heat sensitive substrates. Thus far, HFCVD has been used mainly for the deposition of diamond films, but implementation of this technique for the growth of ceramics is not far in the future. 

Heat-sensitive materials may be sterilized by radiation, providing the product and its container are not radiation sensitive. It is particularly used with plastics, and more widely used with containers than with products. An alternative is ethylene oxide gas. This presents problems in that the gas must be brought into contact with the cell walls of contaminating bacteria. Ethylene oxide is highly reactive and can only be used when it can be proved not to react with the product. 

EXPLOSION and FIRE CONCERNS flammable NFPA rating Health 1, Flammability 3, Reactivity 0 reacts with hydrogen peroxide and nitric acid to form a heat-and shock-sensitive explosive product ignites on contact with potassium tert-butoxide mixture with 2-propanol produces explosive peroxides during storage incompatible with chlorosulfonic acid and oleum flashback along vapor trail may occur use alcohol foam, carbon dioxide, and dry chemical for firefighting purposes. 

EXPLOSION and FIRE CONCERNS pure product is nonflammable and noncombustible liquid if contaminated, material may explode when heated under confinement NFPA rating Health 4, Flammability 0, Reactivity 3 closed container may rupture violently when heated can be shocked into detonation above a critical volume forms shock- and heat-sensitive explosive mixture with 3-bromopropyne reacts violently with aniline and heat, alcoholic sodium hydroxide, sodium methoxide, and propargyl bromide decomposes explosively at elevated temperatures hazardous decomposition products include carbon dioxide, carbon monoxide, and very toxic fumes of CF and oxides of nitrogen use carbon dioxide, dry chemical powder or appropriate foam for firefighting purposes. 

EXPLOSION and FIRE CONCERNS combustible liquid and vapor NFPA rating Health 1, Flammability 2, Reactivity 0 explosive vapor-air mixtures may be formed above 48°C (118°F) flashback along vapor trail may occur closed containers may explode when heated sensitive to static discharge contact with strong oxidizers may cause fire may form explosive peroxides attacks some forms of plastics incompatible with strong acids, alkalies, and oxidizers hazardous decomposition products include carbon monoxide and carbon dioxide use alcohol-resistant foam, dry chemical or carbon dioxide for firefighting purposes. 

Advantages. An important ecological advantage is that only reactive products are used this means that there is no solvent recovery problem and no pollution. Energy consumption is low. Curing is performed at room temperature so heat-sensitive substrates can be used. 

Succinimide is readily silylated by HMDS 2 to the N-silylated product 201, which seems, however, to be in equilibrium with the O-silylated derivative 202 a (cf the closely related reactive center in persilylated uridine 3) and reacts after 6-10 days at 24 °C with one equivalent of primary or secondary amines such as morpholine to give the crystalline colorless cyclic acylamidine 203 and HMDSO 7, even in the absence of any protective gas [33] (Scheme 4.12). The reaction is much faster on heating to 120 °C under argon. At these temperatures 201 and 202 a, and possibly also the acylamidine 203, are apparently partially O-silylated by HMDS 2 to the very sensitive 2,5-bis(trimethylsilyloxy)pyrrole 202b or to 2-tri-... 

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