Lead acetate organic compounds

Upon fusion with caustic alkah (for experimental details, see Section IV,33,2) and acidification of the aqueous extract, hydrogen sulphide is evolved (detected by lead acetate paper). This test is given by aU organic compounds of divalent sulphur (RSH, R SR" and R SSR"). 

When an organic compound is heated with a mixture of zinc powder and sodium carbonate, the nitrogen and halogens are converted into sodium cyanide and sodium hahdes respectively, and the sulphur into zinc sulphide (insoluble in water). The sodium cyanide and sodium hahdes are extracted with water and detected as in Lassaigne s method, whilst the zinc sulphide in the residue is decomposed with dilute acid and the hydrogen sulphide is identified with sodium plumbite or lead acetate paper. The test for nitrogen is thus not affected by the presence of sulphur this constitutes an advantage of the method. 

Lead oxide is used in producing fine "crystal glass" and "flint glass" of a high index of refraction for achromatic lenses. The nitrate and the acetate are soluble salts. Lead salts such as lead arsenate have been used as insecticides, but their use in recent years has been practically eliminated in favor of less harmful organic compounds. 

When appreciable amounts of pectin, proteins, lipids, unwanted polyphenols, or other compounds are suspected to be present in anthocyanin-containing extracts, some of them can be precipitated or the anthocyanins may be crystalhzed and separated from the others. Pectin and proteins can be removed by organic solvents such as methanol and acetone in order to reduce their solubility, then precipitated and separated by centrifugation. Gelatin was used to remove proanthocyanidin due to its high molecular weight. Anthocyanins were reported to be precipitated early by lead acetate to achieve isolation from other materials. ... 

Melanin compounds may appear brown, black, or red. The type of melanin determines hair color, and the density of melanin granules determines the shade. Dark shades of dyed hair contain higher concentrations of dyes. Most hair colors are combinations of organic compounds chosen to produce particular shades. Resorcinol produces a yellow color aminohydroxy-toluene produces a redder hair, and nitrophenylenediamine dye results in very red hair. Graded dyes favored by men often contain lead acetate. The lead ions penetrate into hair and form lead sulfide (PbS), a dark-colored compound. 

Lead is rapidly corroded by dilute acetic acid or formic acid in the presence of oxygen. The tolerance of lead towards sodium or potassium hydroxide up to 30 percent alkali at 25°C or 90°C has proven useful in refining petroleum involving sulfuric acid treatment followed by alkali treatment in a lead-lined tank. Detailed data on corrosion rates of lead exposed to organic compounds are found in the literature.74... 

Assay Transfer about 1.2 g of sample, accurately weighed, into a 250-mL beaker, and dissolve in 75 mL of water. Add 25 mL of 1 N acetic acid and 1.0 mL of diphenylcarbazone TS, and titrate slowly with 0.1 M mercuric nitrate to the first appearance of a purple color. Each milliliter of 0.1 M mercuric nitrate is equivalent to 37.43 mg of C1oH12CaN2Na208. Lead Determine as directed for the Dithizone Method under Lead Limit Test, Appendix MB, using a Sample Solution prepared as directed for organic compounds, but use 70%... 

Assay Dissolve about 200 mg, accurately weighed, in 3 mL of formic acid and 50 mL of glacial acetic acid, add 2 drops of crystal violet TS, and titrate with 0.1 A perchloric acid to a green endpoint or until the blue color disappears completely. Each mL of 0.1 A perchloric acid is equivalent to 8.710 mg of CgHi4N402. Lead A Sample Solution prepared as directed for organic compounds meets the requirements of the Lead Limit Test, Appendix IIIB, using 10 pg of lead ion (Pb) in the control. 

Figure 25 Anaerobic decomposition with sulfate reduction as the terminal step. Fermentation leads to several possible products including low molecular weight organic acids and alcohols and hydrogen and carbon dioxide. Incomplete oxidizers (i) produce acetate as an end product, whereas complete oxidizers (c) mineralize organic compounds, including acetate, to carbon dioxide.

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