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The double bonds of an unsaturated fatty acid can be cleaved by free-radical reactions involving molecular oxygen. This reaction causes the release of malodorous and highly volatile aldehydes and ketones. Because of the nature of free-radical reactions, the reaction is catalyzed by sunlight. [7] Oxidation primarily occurs with unsaturated fats.
The bulk of the polymer is therefore photo-inert and degradation is instead attributed to the presence of various impurities, which are introduced during the manufacturing or processing stages. These include hydroperoxide and carbonyl groups, as well as metal salts such as catalyst residues. All of these species act as photoinitiators. [4]
Should the brown colour not disappear, possibly due to the presence of an alkene which doesn't react, or reacts very slowly with, bromine, the potassium permanganate test should be performed, in order to determine the presence or absence of the alkene. [2] The iodine value is a way to determine the presence of unsaturation quantitatively.
28.2% (sunlight energy collected by chlorophyll) → 68% is lost in conversion of ATP and NADPH to d-glucose, leaving; 9% (collected as sugar) → 35–40% of sugar is recycled/consumed by the leaf in dark and photo-respiration, leaving; 5.4% net leaf efficiency. Many plants lose much of the remaining energy on growing roots.
In chemistry, the bromine number is the amount of bromine (Br 2) in grams absorbed by 100 g of a sample.The bromine number was once used as a measure of aliphatic unsaturation in gasoline and related petroleum samples, but this assay has fallen into disuse with the introduction of spectroscopic and chromatographic analyses.
The protection of food from photodegradation is very important. Some nutrients, for example, are affected by degradation when exposed to sunlight. In the case of beer, UV radiation causes a process that entails the degradation of hop bitter compounds to 3-methyl-2-buten-1-thiol and therefore changes the taste. As amber-colored glass has the ...
Bromine water, Br 2. Bromine water is an oxidizing, intense brown mixture containing diatomic bromine (Br 2) dissolved in water (H 2 O). [1] It is often used as a reactive in chemical assays of recognition for substances which react with bromine in an aqueous environment with the halogenation mechanism, mainly unsaturated carbon compounds (carbon compounds with 1 or more double or triple bond(s)).
The same conversion can be effected with elemental bromine in the presence of UV light or even sunlight. Toluene may also be brominated by treating it with HBr and H 2 O 2 in the presence of light. [31] C 6 H 5 CH 3 + Br 2 → C 6 H 5 CH 2 Br + HBr. Benzoic acid and benzaldehyde are produced commercially by partial oxidation of toluene with oxygen.