Litharge

This is red lead monoxide, used as in inorganic accelerator for the curing of soft natural rubber lining in an autoclave. High temperature curing leads to blooming of lead film, which is the chemical resistance layer, but impairs bonding with metal. 

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Lead ll) oxide, PbO, exists in two forms as orange-red litharge and yellow massicot. Made by oxidation of Pb followed by rapid cooling (to avoid formation of Pb304). Used in accumulators and also in ceramics, pigments and insecticides. A normal hydroxide is not known but hydrolysis of lead(II) oxyacid salts gives polymeric cationic species, e.g. [Pb OfOH) ] and plumbates are formed with excess base. 

Finely divided lead, when heated in air, forms first the lead(II) oxide, litharge , PbO, and then on further heating in an ample supply of air, dilead(II) lead(IV) oxide, red lead , Pb304. Lead, in a very finely divided state, when allowed to fall through air, ignites and a shower of sparks is produced. Sueh finely divided powder is said to be pyrophoric . It can be prepared by carefully heating lead tartrate. 

When cinnamaldehyde, succinic acid and acetic anhydride are heated in the presence of litharge (PbO), the aldehyde and the succinic acid condense to give the dicarboxylic acid (I), which undergoes decarboxylation to give the pale yellow crystalline 1,8-diphenyloctatetrene (II), Kuhn has shown that as the... 

Laughing gas, see Nitrogen(I) oxide Lautarite, see Calcium iodate Lawrencite, see Iron(II) chloride Lechatelierite, see Silicon dioxide Lime, see Calcium oxide Litharge, see Lead(II) oxide... 

Lead copper litharge (contains high bismuth)... 

Lead Monoxide. Lead monoxide (litharge), PbO, occurs as a reddish alpha form, which is stable up to 489°C where it transforms to a yellow beta form (massicot). The latter is stable at high temperatures. The solubihty of a-PbO ia water is 0.0504 g/L at 25°C the solubihty of the p-PbO is 0.1065 g/L at 25°C (40). Lead monoxide is amphoteric and dissolves ia both acids and alkahes. In alkahes, it forms the plumbite ion PbO - The monoxide is produced commercially by the reaction of molten lead with air or oxygen ia a furnace. Black or gray oxide is manufactured by the Barton process, by the oxidation of atomized molten lead ia air, as well as by the ball mill process, ia which metallic lead balls of high purity are tumbled ia the mill to form partially oxidized lead particles. 

Lead borate moaohydrate [14720-53-7] (lead metaborate), Pb(B02)2 H20, mol wt 310.82, d = 5.6g/cm (anhydrous) is a white crystalline powder. The metaborate loses water of crystallization at 160°C and melts at 500°C. It is iasoluble ia water and alkaHes, but readily soluble ia nitric and hot acetic acid. Lead metaborate may be produced by a fusion of boric acid with lead carbonate or litharge. It also may be formed as a precipitate when a concentrated solution of lead nitrate is mixed with an excess of borax. The oxides of lead and boron are miscible and form clear lead-borate glasses in the range of 21 to 73 mol % PbO. 

This class includes 2inc oxide (pure) and stearic acid. Other compounds that have been in use are litharge, magnesium oxide, amines, and amine soaps. 

Lead Oxides Leady litharge containing 25 to 30 percent free lead is required for storage-batteiy plates. It is processed on Raymond Imp mills. They have the ability to produce litharge that has a desired low density of 1.1 to 1.3 ff/cm (18 to 22 g/iu ). A 56-kW (75-hp) unit produces 860 kg/h (1900 Ib/h) of materialhaving this density. 

The resulting -aminocaproic acid hydrochloride is treated in a manner similar to that used in the preparation of df-alanine (Org. Syn. Coll. Vol. i, 20). The hydrochloride is dissolved in r 1. of water in a 1.5-I. beaker and treated successively with 50 g. of powdered litharge, 25 g. of powdered litharge, 5 g. of freshly precipitated lead hydroxide, 25 g. of powdered silver oxide (Note 2), and finally hydrogen sulfide. During this procedure, the original volume is maintained by the addition of small amounts of water. 

Much confusion exists concerning the number, composition, and structure of the oxides of lead. PbO exists as a red tetragonal form (litharge) stable at room temperature and a yellow orthorhombic form (massicot) stable above 488°C. Litharge (mp 897°, d 9.355 gcm ) is not only the most important oxide of Pb, it is also the most widely used inorganic compound of Pb (see Panel on p. 386) it is made by reacting molten Pb with air or O2 above 600° and has the SnO structure (p. 383, Pb-O 230 pm). Massicot (d 9.642 gcm ) has... 

Frisch-blei, n. refined lead, -dampf, m. live steam, -eisen, n. refined iron, frischen, v.t. fine, refine revive (litharge) ... 

Fuss g ger, m. pedestrian. geleok, n. ankle joint. gestell, n. pedestal, base, foot. glatte, /. black, impure litharge, -mehl, n. the lowest grade of flour, -note, / footnote, -pfund, n. foot pound, -puder, m. foot powder, -punkt, m. (Math.) foot (Aetron.) nadir base. -teppich, m. carpet, rug. -wurzel, /. tarsus, -zehe, /. toe. -zylinder, m. cylinder with a base. 

Gold-glatte, /. a kind of litharge, -glimmer, m. yellow mica, -gnibe, /. gold mine, -grund,... 

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