Tetracetate

three-necked flask is fitted with a thermometer and mercury-sealed stirrer. A mixture of 1080 g. of glacial acetic acid and 360 g. of acetic anhydride is placed in the flask, and then, with the stirrer revolving rapidly, 600 g. of dry minium is added. It is best to add the red lead oxide gradually in small portions so that it will not cake. Care should be taken that the temperature does not rise above 65°C. Toward the end of the reaction, it may be necessary 

Another 200 g. of the product may be obtained from the mother liquor following the directions of Colson.3 The liquid is returned to the original flask, heated to 80°C., with stirring, and a stream of dry chlorine passed into it. When the reaction is complete, the solution is filtered while hot, and the precipitated lead chloride is washed with hot glacial acetic acid. On cooling, lead tetracetate is deposited from the filtrate. This second crop is contaminated with lead chloride and must be recrystallized if a pure material is desired. 

Submitted by R. C. Young and Hewitt G. Fletcher Checked by W. C. FERNELiusf and E. W. BowERMANf 

When the water vapor is completely expelled, the end of the tube is fitted with a cork stopper bearing a straight calcium chloride tube loosely packed to prevent plugging. The nitrogen is now allowed to pass through bromine at the rate of approximately one bubble per second and then is directed into the reaction tube. As the reaction proceeds, a sublimate of zirconium bromide collects in the tube several centimeters beyond the furnace. 

The major portion of this sublimate collects in a small section of the tube and if a plug forms, it may be removed by heating with a free flame that section of the tube in which it occurs. A considerable quantity of the bromide will be carried along in the stream of nitrogen, even through the tube of calcium chloride.  

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Lead tetracetate. Red lead is warmed with acetic acid in the presence of sufficient acetic anhydride to combine with the water formed ... 

Methyl free radicals, generated either by thermolysis of lead tetracetate in acetic acid solution (401) or by radical cleavage of dimethylsulfoxide by H2O2 and iron (II) salts (408), afford 2- and 5-methylthiazole in the proportion of 86 and 14%, respectively, in agreement with the nucleophilic character of alkyl free radicals and the positive charge of the 2-carbon atom of the thiazole (6). 

Perbenzoic acid gave a doubly unsaturated triol monobenzoate. Only two hydroxyl groups could be acetylated, and one was tertiary. The saturated triol reacted with lead tetracetate to give an a glycol. When reacted with chromic acid, it gave a hydroxy lactone. From these observations, Windaus and Gmndmann (11) described the correct stmcture for ergosterol (1). 

Determination. The most accurate (68) method for the deterrnination of copper in its compounds is by electrogravimetry from a sulfuric and nitric acid solution (45). Pure copper compounds can be readily titrated using ethylene diamine tetracetic acid (EDTA) to a SNAZOXS or Murexide endpoint. lodometric titration using sodium thiosulfate to a starch—iodide endpoint is one of the most common methods used industrially. This latter titration is quicker than electrolysis, almost as accurate, and much more tolerant of impurities than is the titration with EDTA. Gravimetry as the thiocyanate has also been used (68). 

Lead tetracetate Acetic acid, lead (4+) salt (8,9) (546-67-8)... 

Witkop applied the lead tetracetate process to opoyohim-bine, and obtained tetradehydroapoyohimbic acid, ... 

To 1,000 g of the crude reaction product a re added 264g of ethylene diamine tetracetic acid. The mixture is preferably heated to incipient boiling to increase the rate of reaction,and then the mixture is allowed to cool and crystallize. The crystals formed are filtered off, washed with the smallest possible amount of ice water, and dried to a constant weight, which is 452 g. 

To a solution of 6.36 parts of 17(3-hydroxy-17a-methyl-5o -androst-Ten-3-one in 95 parts of acetic acid and 12 parts of water is added 40 parts of lead tetracetate and 0.6 part of osmium tetroxide. This mixture is stored at room temperature for about 24 hours, then is treated with 2 parts of lead tetracetate. Evaporation to dryness at reduced pressure affords a residue, which is extracted with benzene. The benzene extract is washed with water, and extracted with aqueous potassium bicarbonate. The aqueous extract is washed with ether, acidified with dilute sulfuric acid, then extracted with ethyl acetate-benzene. This organic extract is washed with water, dried over anhydrous sodium sulfate, and concentrated to dryness in vacuo. To a solution of the residual crude product in 20 parts of pyridine is added 10 parts of 20% aqueous sodium bisulfite and the mixture is stirred for about 20 minutes at room temperature. 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

Potassium permanganate in neutral solution and lead tetracetate give rise, respectively, to the anticipated glycol and to its diacetate. 

Ethylene Diamine Tetracetic Acid and Nitriloacetic Acid. . . ... 

Calcium is titrated with EGTA (l,2-bis-(2-amminoethoxyethane N,N,N, N -tetracetic acid) in the presence of the zinc complex of zincon as indirect indicator for calcium. Theoretical titration curves are calculated by means of the computer program HALTAFALL in order to assess accuracy and precision. The method gives a relative precision of 0.00028 when applied to estuarine water of 0.05-0.35% salinity. 

The dehydrogenation of dioximes symmetrically substituted (17, R=Ri, Scheme 6.4) with a variety of oxidants, including potassium ferricyanide, halogens, hypohalides, nitric acid, nitrogen dioxides, and lead tetracetate, is a common route to symmetrically substituted furoxans. 

Treatment of 3-rncthyl A-cthoxycarbonyl-5-aryIidcnchydrazono-l//-pyrazolcs 194 with bromine, in the presence of sodium acetate, in acetic acid gives substituted ethyl 3-aryl-7-cthoxycarbonyI-6-rncthyl-1 //-pyrazolo[5,1 -/ -[l,2,4]triazoles 55 (Equation 35) <2002ARK133>. Analogously, the reaction of compounds 194 with lead tetracetate [Pb(OAc)4] in acetic acid also gives l//-pyrazolo[5,l-c][l,2,4]triazoles 55 (unreported yield) (Equation 35) <2002ARK133>. 

Aliphatic hydrocarbons, triazine, substituted urea type and phenoxyacetic acid types of herbicides, Fluazifop and Fluazifop-butyl herbicides, ethylene diamine tetracetic acid salts in soil, aliphatic and polyaromatic hydrocarbons, phthalate esters, various organosulphur compounds, triazine herbicides, optical whiteners, mixtures of organic compounds and organotin compounds in non-saline sediments, aromatic hydrocarbons, humic and fulvic acids and mixtures of organic compounds in saline sediments and non-ionic surfactants and cobalamin in sludges. 

Singhal et al. [78, 79] have described a titrimetric method for the determination of low levels of Oxamyl residues in soils. Their investigations revealed that after hydrolysis Oxamyl gave a brown precipitate with carbon disulphide and an alkaline solution of copper(II) sulphate. This reaction suggested a procedure for the determination of Oxamyl by titration with ethylene diamine tetracetic acid of the copper remaining unreacted to the 1-(2 pyridylazo)-2-naphthol end-point indicator). The following stoichiometric reaction appeared to occur between Oxamyl and the reagents ... 

Waggot and Britcher [38] have discussed experimental considerations in the determination of organic carbon content of sewage effluent. Close attention is paid to the determination of particular classes of organic compounds in sewage including carbohydrates, amino acids, volatiles, steroids, phenols, surface active materials, fluorescent materials, organochlorine pesticides and ethylene diamine tetracetic acid. 

Ethylenediamine tetracetic acid (H4Y) undergoes ionization at four, different stages, namely ... 

In reality, the actual complexing species is the tetracetate ion i.e., Y4 therefore, complexation will take effect more efficiently and be more stable in an aikaline medium. Hence, it is evident that EDTA complexes of many divalent metals are quite stable in ammoniacal solution. 

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