Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Colour organic compounds

The photographs show the structures of coloured organic compounds. [Pg.51]

You ve already met the orange pigment p-carotene. Eleven C=C double bonds make up most of its structure. Coloured organic compounds often contain chains of C=C double bonds like this. In Chapter 7 you will find out why this is so. [Pg.32]

Parallel and side reactions occur resulting in undesired by-products including dark coloured organic compounds take place, promoted by high temperatures and long reaction times. [Pg.99]

The dialysis serves to separate nitrate ions from interfering substances like colloids and coloured organic compounds. [Pg.119]

If triphenylmethyl chloride in ether is treated with sodium, a yellow colour is produced due to the presence of the anionic spiecies PhsC". Alternatively, if triphenylmethyl chloride is treated with silver perchlorate in a solvent such as THF, the triphenylmethyl cation is obtained. More conveniently, triphenylmethyl salts, PhsC X", can be obtained as orange-red crystalline solids from the action of the appropriate strong acid on triphenylcarbinol in ethanoic or propanoic anhydride solution. The perchlorate, fluoroborate and hexafluoro-phosphate salts are most commonly used for hydride ion abstraction from organic compounds (e.g. cycloheptatriene gives tropylium salts). The salts are rather easily hydrolysed to triphenylcarbinol. [Pg.406]

The bromine test is applied first. The organic compound, if a liquid, is treated with 2-3 drops of liquid bromine or (preferably) a solution of bromine in carbon tetrachloride if the organic compound is a solid, it should first be dissolved in cold carbon tetrachloride or chloroform. The rapid absorption of the bromine (and consequent disappearance of the red colour) is a strong indication that the compound is unsaturated, and is therefore undergoing direct addition of the bromine. [Pg.85]

J. Berry, "Control of Volatile Organic Compound (V OC) Emissions from Painting Operations ia the United States," Polymers Paint Colour J. 181(4281), (Apr. 17,1991). [Pg.328]

Development of extraction-free photometric procedures for the determination of traces of metals for which hygienic and environmental regulations have been established is an urgent problem. For solution of this problem we used as an organic reagent l-(2- pyridylazo)-naphtol-2 (PAN) which forms intensely coloured complex compounds with many metals and is frequently used for their extraction-photometric determination however these procedures did not find wide application in water analysis due to lack of selectivity and necessity of using organic solvents. [Pg.199]

Sulphur.—The presence of sulphur in organic compounds may be detected by heating the substance with a little metallic sodium or potassium. The alkaline sulphide, when dissolved in water, gives a violet colouration with a solution of sodium nitro-prusside. Heat a fragment of gelatine with a small piece of potassium in a test-tube until the bottom of the tube is red hot, and place it m a small beaker of water as described in the test for nitrogen (p. 2). Filter the liquid and add a few drops of sodium nitroprusside solution. [Pg.3]

Colour in organic compounds is also due to resonance. This also explains why a system of open conjugate double bonds containing two or more double bonds imparts colour to it. [Pg.218]


See other pages where Colour organic compounds is mentioned: [Pg.51]    [Pg.37]    [Pg.114]    [Pg.103]    [Pg.235]    [Pg.411]    [Pg.47]    [Pg.47]    [Pg.47]    [Pg.37]    [Pg.51]    [Pg.37]    [Pg.114]    [Pg.103]    [Pg.235]    [Pg.411]    [Pg.47]    [Pg.47]    [Pg.47]    [Pg.37]    [Pg.231]    [Pg.338]    [Pg.1145]    [Pg.20]    [Pg.16]    [Pg.18]    [Pg.3]    [Pg.505]    [Pg.586]    [Pg.678]    [Pg.1145]    [Pg.531]    [Pg.2]    [Pg.17]    [Pg.217]    [Pg.449]    [Pg.10]    [Pg.99]    [Pg.158]    [Pg.25]    [Pg.67]    [Pg.231]    [Pg.217]    [Pg.217]    [Pg.332]   


SEARCH



COLOUR COMPOUND

Colour Compounding

Colourants organic

Coloured compound

Organic compounds coloured

Organic compounds coloured

© 2024 chempedia.info