Lead -acetate

Another method which should be cited apart from the others is to pyrolyze the sample in a hydrogen atmosphere. The sulfur is converted to H2S which darkens lead-acetate-impregnated paper. The speed of darkening, measured by an optical device, provides the concentration measurement. This method attains sensitivity thresholds of 0.02 ppm. 

Lead formate is only slightly soluble in cold water, and insoluble in hot absolute ethanol it can therefore be readily distinguished from lead acetate or sugar of lead because, quite apart from chemical tests, the acetate is readily soluble in cold water and moderately soluble in ethanol. 

Allow the reddish-yellow solution to cool to about 40° and then filter off at the pump the polyene which has separated this filtration should be performed as rapidly as possible to avoid contamination with lead acetate, and a Buchner funnel of not less than 6 cm. diameter should therefore be used to avoid clogging the filter. Wash the crude production the filter with... 

Sodium mlphanilate.—Burns with difficulty, leaving a residue of (chiefly) sodium sulphide. Add dil. HCl, and confirm without delay the evolution of HjS by means of a filter-pa per moistened with lead acetate solution. Typical of salts of the sulphonic acids. Acetone sodium bisulphite.—Almost non-inflammable, leaving a colourless residue of sodium sulphite and sulphate. Transfer residue to a test-tube, add dil. HCl, warm, and confirm the SO2 evolved. 

Sulphur. Moisten the centre of a filter-paper with lead acetate solution. Then add about 10 ml. of dilute hydrochloric acid to the residue in the evaporating-basin, and at once cover the latter with the paper. If zinc sulphide is present in the residue, the hydrogen sulphide evolved will give a definite daA brown coloration with the lead acetate paper. The presence of hydrogen sulphide can often be confirmed by its odour. 

Removal of sulphur as sodium sulphide. Dissolve about 0 i g. of c> stine in a few ml. of 10% NaOH solution. Add a few drops of lead acetate solution and boil for 1 minute. The solution darkens owing to the formation of lead sulphide. 

The filtrate, which contains lead acetate, may be treated with chlorine ... 

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"). 

Sulphur, as sulphide ion, is detected by precipitation as black lead sulphide with lead acetate solution and acetic acid or with sodium plumbite solution (an alkaLine solution of lead acetate). Halogens are detected as the characteristic silver halides by the addition of silver nitrate solution and dilute nitric acid the interfering influence of sulphide and cyanide ions in the latter tests are discussed under the individual elements. 

Prepare a solution of sodium plumbite by adding 10 per cent, sodium hydroxide solution to a few drops of about N lead acetate solution until the white precipitate of lead hydroxide initially formed just redissolves to a clear solution. Add 1 ml. of the fusion solution the presence of sulphiu- is indicated by a black precipitate of lead sulphide. 

Acidify 2 ml. of the fusion solution with dilute acetic acid, and add a few drops of lead acetate solution. A black precipitate of lead sulphide indicates the presence of sulphur. 

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. 

Strike got the journal article for this recipe as literature citation used in the original Wacker oxidation Strike used for Method 2. In it both mercuric acetate, and to an extent, lead acetate produced ketones as described. Someone-Who-ls-Not-Strike also got a certain ketone. But maybe they were lucky or just plain wrong. Most people on Strike s site say this mercuric acetate thing... 

Compound 265 may be transformed into its urea counterpart by the action of lead acetate (102). 

Both objectives have been met by designing special hydrogenation catalysts The most frequently used one is the Lindlar catalyst, a palladium on calcium carbonate combi nation to which lead acetate and quinoline have been added Lead acetate and quinoline partially deactivate ( poison ) the catalyst making it a poor catalyst for alkene hydro genation while retaining its ability to catalyze the addition of H2 to the triple bond... 

Salicylic acid Iodine, iron salts, lead acetate... 

Acetone was originally observed about 1595 as a product of the distillation of sugar of lead (lead acetate). In the nineteenth century it was obtained by the destmctive distillation of metal acetates, wood, and carbohydrates with lime, and pyrolysis of citric acid. Its composition was determined by Liebig and Dumas in 1832. 

Ma.nufa.cture. Lead azide is typically made from sodium azide [26628-22-8] in small (eg, 5 kg) batches buffered by the reaction solutions of lead nitrate or lead acetate ... 

Lead styphnate monohydrate is precipitated as the basic salt from a mixture of solutions of magnesium styphnate and lead acetate followed by conversion to the normal form by acidification using dilute nitric acid (97—99). 

PbF2 is readily prepared by the action of hydrogen fluoride on lead hydroxide, lead carbonate, or a-lead oxide. It can also be obtained by precipitation from lead nitrate or lead acetate solutions using potassium fluoride, ammonium fluoride, or ammonium bifluoride. 

Metallic Dyes. MetaUic dyes are among the older hair color materials known. Commercial products are based on a 1% solution of lead acetate in an aqueous, slightly acidic, alcohoHc medium. Precipitated sulfur appears to be essential. The convenience aspect is stressed by the leave-in appHcation method. Actually, the color development is so slow, taking about a week to ten days, that there is no alternative to this technique. Daily appHcation is needed at first. 

Although lead acetate [301-04-2] is the only metallic dye used ia the early 1990s, salts or silver, copper, nickel, cobalt, bismuth, and iron have been utilized ia the past. A patent (39) refers to the use of bismuth citrate ia a solution made alkaline with triisopropan ol amine. 

Lead acetate can be used only for coloring scalp hair at a level not to exceed 0.6%, as lead, weight/volume of the product. The regulations provide specific restrictions (including label specifications) that lead acetate must not be used to color mustaches, eyelashes, eyebrows, or hair on parts of the body other than the scalp. 

Dilead hexacyanokisferrate [14402-61 -0] Pb2[Fe(CN)g], is a white precipitate that forms when lead acetate is added to Ca2[Fe(CN)g]. It is insoluble in water or dilute acids but is soluble in hot ammonium chloride or ammonium succinate solutions. It has been used as a quaUtative analytical reagent in tests for cadmium and chromate. 

Acid Oxidation. Reactions of lead with acid and alkaUes are varied. Nitric acid, the best solvent for lead, forms lead nitrate acetic acid forms soluble lead acetate in the presence of oxygen sulfuric acid forms insoluble lead sulfate. Sulfuric acid is stored in containers with chemical or acid-grade lead. Lead dissolves slowly in HCl, but in the presence of aqueous alkaUes forms soluble plumbites and plumbates. 

Lead Chloride. Lead dichloride, PbCl2, forms white, orthorhombic needles some physical properties are given in Table 1. Lead chloride is slightly soluble in dilute hydrochloric acid and ammonia and insoluble in alcohol. It is prepared by the reaction of lead monoxide or basic lead carbonate with hydrochloric acid, or by treating a solution of lead acetate with hydrochloric acid and allowing the precipitate to settle. It easily forms basic chlorides, such as PbCl Pb(OH)2 [15887-88 ] which is known as Pattinson s lead white, an artist s pigment. 

Basic Lead Acetate. Basic lead acetate [1335-32-6] (lead subacetate), 2Pb(0H)2-Pb(C2H3 02 )2, is a heavy white powder which is used for sugar analyses. Some physical properties are given in Table 4. Reagent grade is available in 11.3-kg cartons and in 45- and 147-kg fiber dmms. 

Lead Carbonate. Lead carbonate [598-63-0] PbCO, mol wt 267.22, d = 6.6g/cm, forms colorless orthorhombic crystals it decomposes at about 315°C. It is nearly insoluble in cold water (0.00011 g/100 mL at 20°C), but is transformed in hot water to the basic carbonate, 2PbC03 Pb(OH)2. Lead carbonate is soluble in acids and alkalies, but insoluble in alcohol and ammonia. It is prepared by passing CO2 iuto a cold dilute solution of lead acetate, or by shaking a suspension of a lead salt less soluble than the carbonate with ammonium carbonate at a low temperature to avoid formation of basic lead carbonate. 

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