Rapid heating effect

Nitrophenylpyruvic acid was reduced to oxindole using iron pin-dust-ferrous sulfate in water. The iron oxide-iron residues, after filtering and washing with chloroform, rapidly heated in contact with air and shattered the Buchner funnel [1], Previously, rapid heating effects had been observed on sucking air through the iron oxide residues from hot filtration of aqueous liquor from reduction of a nitro compound with reduced iron powder [2],... 

Section 6.4.7.) No attempt was made to explore the mech-anism(s) responsible for these observations, although the role of the glycerol matrix (that is essentially completely transparent at 337 nm) was assumed to be that of replenishment of analyte to the region of the surface irradiated and ablated by the laser. The fine metal particles were essential for the success of the method, ascribed to the high photo-absorption, low heat capacity and extremely large ratio of surface area to volume of these particles, which were assumed to couple the laser photons to the analyte via the rapid heating effect (see the text box in this Chapter). 

The heating effect is the limiting factor for all electrophoretic separations. When heat is dissipated rapidly, as in capillary electrophoresis, rapid, high resolution separations are possible. For electrophoretic separations the higher the separating driving force, ie, the electric field strength, the better the resolution. This means that if a way to separate faster can be found, it should also be a more effective separation. This is the opposite of most other separation techniques. 

Unsaturated (drying) oils, like linseed oil, etc., will rapidly heat and ignite when distributed on active carbon, owing to the enormous increase in surface area of the oil exposed to air, and in the rate of oxidation, probably catalysed by metallic impurities [1]. A similar, but slower, effect occurs on fibrous materials such as cotton waste [2],... 

The epoxide and the nitrogen compound were mixed and stirred in a 250 1 reactor fitted for reflux and protected by a rupture disk. After addition of the catalyst, subsequent heating to the required temperature seems to have been effected by direct application of steam to the jacket, rather than the usual hot water. The too-rapid heating led to a violently exothermic reaction which ruptured the disk and stretched the lid clamping bolts. 

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