Carbonate method

The composition of coal tar varies with the carbonization method but consists, largely, of mononuclear and polynuclear aromatic compounds and their derivatives. Coke oven tars are relatively low in aliphatic and phenolic content while low-temperature tars have much higher contents of both. 

For brines having very low iodide concentrations, ie, in some facilities in Japan and in the former USSR, the activated carbon method of recovery is used. This method consists of a process involving the treating of the acidified brine with sodium nitrite in large tanks, where the following reaction takes place ... 

Halogen, sulphur, nitrogen content Ash content Analysis of ash Organic content by BOD, COD, PV or total carbon methods completed... 

A further variant of Method B is the conversion of the readily available aryl(2-methyl-aminoaryl)methanols 16 into the chloroacelyl derivatives 17, followed by oxidation to Ihe benzophenones 18 with chromium(VI) oxide. The products are transformed into benzodi-azepinones by treatment with sodium iodide and ammonium carbonate (Method D). Selected... 

Depending on the extraction method and the source of Rb and Cs, the elements are obtained in industry as chlorides, nitrates and carbonates. Methods of preparing and purifying all of the alkali metals are described with examples. Methods for Rb and Cs are governed by the relative ease of reduction of their compounds, the volatility of the extracted metal and the extreme chemical reactivity of these heavier alkali metals toward air and moisture. 

Of the methods in common use, the two wet oxidation methods offer the best possibilities for further development. The photo-oxidation method in particular is well suited to automatic analysis. In the version of the total organic carbon method published by Collins and Williams [30] the effluent from the quartz photolysis coil could as easily be diverted to the nitrate analysis unit if inorganic nitrogen were also measured, organic nitrogen could become a routine automatic method. 

ISO 176, Plastics - Determination of loss of plasticizers - Activated carbon method, 1976. 

The combination of the carbonyl protection method and the addition of the potassium carbonate method is advantageous 2,4-Diacetylphenol can be obtained from the acetal of 4-acetylphenyl acetate in 80% yield by irradiation in hexane in the presence of anhydrous K2CO3 [207]. In this experiment, the base avoids deprotection of the starting material. 

Requires lower materials costs than other activated carbon methods. 

Topic The barium carbonate method for separating trivalent and bivalent bases Treadwell-Hall, Quantitative Analysis, vol. II, 151, 7th cd. (1928). 

Zinc powder sodium carbonate method for detection of elements, 1043 -1045 ... 

In addition to the THM methods, EMSL-Cincinnati has developed purge and trap methods for selected halogenated (29) and aromatic (30) compounds that are considered to be chemical indicators of industrial contamination. The methods are applicable to 47 halogenated compounds (Method 502) and 33 compounds that have ionization potentials less than 10.2 eV and that are aromatic or contain a doubly bonded carbon (Method 503). Seven of these compounds are halogenated and are also included in the method for halogenated compounds. Another method, Method 524 (31), provides for GC-MS determination of 28 purgeable volatiles. Single laboratory precision and accuracy data for these compounds are provided in the EMSL methods. 

Scheme 36 SPPS of N-Alkylated Peptides by the Bis(trichloromethyl) Carbonate Method,3°l...

A slightly modified version of the bis(trichloromethyl) carbonate method 30 has been used for the total SPPS of cyclosporin O 29 (Scheme 1) and omphalotin A 40 (Scheme 37). Since in this case an acid sensitive trityl resin was used, excess DIPEA was added to the resin. 

Unlike the succinimidyl succinate or succinimidyl glutarate activation methods, succinimidyl carbonate chemistry does not suffer from the presence of a labile ester bond. The intermediate carbonate may hydrolyze in aqueous solution to release NHS and C02, essentially regenerating the underivatized PEG hydroxyl. After coupling to amine-containing molecules, however, the resultant carbamate linkage stabilizes the chemistry to the point that a modified molecule will not lose PEG by hydrolytic cleavage. For these reasons, the succinimidyl carbonate method of PEG activation and... 

Wangersky, P. J. 1993. Dissolved organic carbon methods A critical review. Marine Chemistry 41 61-74. 

Holmes, A.J., Vanderwielen, A.J., Total organic carbon method for aspirin cleaning validation. PDA JPharm Sci Tech, 51 (4), July-Aug 1997. 

The extent of C-alkylation as a side reaction in etherification varies about 1% of allyl 2-allylphenyl ether is formed when phenol is used in the acetone and potassium carbonate method with allyl bromide with cinnamyl bromide or 7,7-dimethylallyl bromide the extent of C-alkylar tion is greater.16 A complicated mixture of C- and O-alkylation products results from the treatment of phenol with 4-bromo-2-hexene and 4-chloro-2-hexene. 9 4-Hexenylresordnol has been obtained in about 40% yield from the reaction of l-bromo-2-hexene, resorcinol, and potassium carbonate in boiling acetone.99 An appreciable amount of C-alkylation occurs when 2,6-dimethyIphenol is treated with allyl bromide and sodium ethoxide in ethanol.70 Since, in general, the ampunt of C-alkylation is greatly increased by carrying out the alkylation on the sodium salt of the phenol in benzene,16 this method is unsuitable for the preparar tion of allyl aryl ethers. 

Measurement of Natural Radiocarbon Concentrations. By the middle of the 1950s, the original solid carbon method of assay of natural radiocarbon concentrations had been completely superseded by the development of either gas or liquid scintillation counting systems. More than 20 years of experimentation and development in the low level counting technology field has turned what was once a black art and analytical tour de... 

Cyclic tra.ns-2,3-Carbonate Method This method was first used for immobilization of different biomolecules on cellulosic materials [143]. The reaction of cellulose with ethyl chloroformate in anhydrous organic solvents gives... 

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