Lead acetate basic reagent

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. 

Fig. 2 The influence of the reagent concentration on the sensitivity of detection detection of equal amounts of luteolin with basic lead acetate solution that was (A) undiluted, (B) diluted 1 + 4 and (C) diluted 1 + 50.

Note that harsher conditions may lead to further changes, e.g. epimerization at C-3 in fmctose, plus isomerization, or even reverse aldol reactions (see Section 10.3). In general, basic conditions must be employed with care if isomerizations are to be avoided. To preserve stereochemistry, it is usual to ensure that free carbonyl groups are converted to acetals or ketals (glycosides, see Section 12.4) before basic reagents are used. Isomerization of sugars via enediol intermediates features prominently in the glycolytic pathway of intermediary metabolism (see Box 10.1). 

ANALYZER (Reagent-Tape). The key to chemical analysis by this method is a tape (paper or fabric) that has been impregnated with a chemical substance that reacts with the unknown to form a reaction product on the tape which lias some special characteristic, e.g., color, increased or decreased opacity, change in electrical conductance, or increased or lessened fluorescence. Small pieces of paper treated with lead acetate, for example, have, been used manually by chemists for many years to determine the presence of hydrogen sulfide in a solution or in the atmosphere. This basic concept forms the foundation for a number of sophisticated instruments that may pietreat a sample gas, pass it over a cyclically advanced tape, and, for example, photo-metrically sense the color of the exposed tape, to establish a relationship between color and gas concentration. Depending upon tile type uf reactiun involved, the tape may he wet or dry and it may be advanced continuously or periodically. Obviously, there are many possible variations within the framework of this general concept. 

Fluorescamines Antimony (III) chloride (10% in chloroform) Benedict reagent Lead (IV) acetate (basic, 25%) p-Toluenesulfonic acid (20% in chloroform) Perchloric acid (70%)... 

A number of reagents in solution give precipitates or heavy jellies on addition to gum arabic solutions borax, ferric chloride (excess redissolved), basic lead acetate (but not neutral lead acetate), potassium and sodium silicates, gelatin, Millon s reagent (12) and Stokes s acid mercuric nitrate reagent (12), Dilute acids hy-... 

Spray reagent 25% aqueous solution of basic lead acetate. 

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