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2,4-Dinitrochlorobenzene (DNCB) is an organic compound with the chemical formula (O 2 N) 2 C 6 H 3 Cl. It is a yellow solid that is soluble in organic solvents . It is an intermediate for the industrial production of other compounds.
2,4-Dinitrophenylhydrazine (2,4-DNPH or DNPH) is the organic compound C 6 H 3 (NO 2) 2 NHNH 2. DNPH is a red to orange solid. It is a substituted hydrazine. The solid is relatively sensitive to shock and friction. For this reason DNPH is usually handled as a wet powder. DNPH is a precursor to the drug Sivifene.
The three possible arrangements of the nitro groups afford three isomers, 1,2-dinitrobenzene, 1,3-dinitrobenzene, and 1,4-dinitrobenzene. Each isomer has the chemical formula C 6 H 4 N 2 O 4 and a molar mass of about 168.11 g/mol. 1,3-Dinitrobenzene is the most common isomer and it is used in the manufacture of explosives .
Because acetic anhydride is not stable in water, the conversion is conducted under anhydrous conditions. To a decreasing extent, acetic anhydride is also prepared by the reaction of ketene with acetic acid at 45–55 °C and low pressure (0.05–0.2 bar). [8] H 2 C=C=O + CH 3 COOH → (CH 3 CO) 2 O (ΔH = −63 kJ/mol)
The LD50 (oral, rats) is 756 mg/kg. Animal studies have shown that 1,2,4-trichlorobenzene affects the liver and kidney, and is possibly a teratogen. [4] There is no regulated occupational exposure limit for chemical exposure, but the National Institute for Occupational Safety and Health recommends no greater exposure than 5 ppm, over an 8-hour workday.
This produces 2,4,6-trichlorobenzoic acid, which can then be refluxed in thionyl chloride to form 2,4,6-trichlorobenzoyl chloride. [4] Since 2,4,6-trichlorobenzoic acid is produced as a by product of the Yamaguchi esterification process, it can be refluxed again to recreate 2,4,6-trichlorobenzoyl chloride.
Acetone and acetic anhydride ((CH 3 C(O)) 2 O) upon the addition of boron trifluoride (BF 3) catalyst: [11] (CH 3 C(O)) 2 O + CH 3 C(O)CH 3 → CH 3 C(O)CH 2 C(O)CH 3 A second synthesis involves the base-catalyzed condensation (e.g., by sodium ethoxide CH 3 CH 2 O − Na + ) of acetone and ethyl acetate , followed by acidification of the sodium ...
Frederick Sanger. In 1945, Frederick Sanger described its use for determining the N-terminal amino acid in polypeptide chains, in particular insulin. [4] Sanger's initial results suggested that insulin was a smaller molecule than previously estimated (molecular weight 12,000), and that it consisted of four chains (two ending in glycine and two ending in phenylalanine), with the chains cross ...