2.4- Dinitrophenylhydrazine derivatives using

Dinitrophenylhydrazine is used in qualitative organic analysis for preparing solid derivatives of carbonyl compounds. ... 

The most satisfactory chemical methods for ascorbic acid analysis are based on the reduction of 2,6-dichlorophenolindophenol or on the formation of a colored dinitrophenylhydrazine derivative. A large number of other reactions, mostly with other oxidizing agents, have been used but have not found general favor (R21). 

Certain compounds that are derivatives of ammonia such as 2,4 dinitrophenylhydrazine add to the carbonyl group to form derivatives useful for the characterization and identification of aldehydes and ketones. The products possess a carbon-nitrogen double bond that was produced from elimination of a molecule of water from the initial addition products. Hence,... 

An apparatus for simultaneously coating a plate with two adjacent layers of different adsorbents was accomplished by placing a plastic insert into a commercial spreader, thus forming two independent chambers. For this reason, combinations of two adsorbents, such as cellulose, silica gel, alumina, charcoal, silicic acid, magnesium silicate, etc. as a function of the sample were used. Then, the two eluents systems were optimized for the two development directions, e.g., 2-D separation of some ketones on a bilayer (charcoal/ silicic acid) with benzene-ether-acetic acid (82 9 9, v/v) in the first direction (on charcoal) and with benzene-ether (85 15, v/v) in the second direction (on silicic acid). In another paper, the first adsorbent was silica gel (air-dried) and the second adsorbent was deactivated aluminum oxide. The same solvent system, toluene-ethyl acetate (3 1, v/v), was used in the two directions. In this condition, a mixture of 2,4-dinitrophenylhydrazine derivatives of hydroxycarbonyl compounds was resolved. 

By far the most common examples of this are with derivatives of NH3, particularly those like HONH2, NH2CONHNH2, PhNHNH2, etc., which have long been used to convert liquid carbonyl compounds into solid derivatives, for their characterisation 2,4-dinitrophenylhydrazine, (N02)2C6H3NHNH2, is particularly useful in this respect. 

In addition to the spectroscopic methods, there are a number of derivatization methods, in which a derivative of the carbonyl compound that can be easily separated and measured is formed. The most common of these is the use of 2,4-dinitrophenylhydrazine (DNPH), which reacts to form the hydrazone ... 

Some commercial samples of precipitated manganese dioxide may be active enough for use directly in an oxidation process. To assess the activity of a sample of manganese dioxide, dissolve 0.25 g of pure cinnamyl alcohol in 50 ml of dry light petroleum (b.p. 40-60 °C) and shake the solution at room temperature for 2 hours with 2g of the sample of manganese dioxide (previously dried over phosphoric oxide). Filter, remove the solvent by evaporation and treat the residue with an excess of 2,4-dinitrophenylhydrazine sulphate in methanolt (Section 9.6.13, p. 1257). Collect the cinnamaldehyde 2,4-dinitrophenyl-hydrazone and crystallise it from ethyl acetate. An active dioxide should give a yield of the derivative, m.p. 255 °C (decomp.), in excess of 0.35 g (60%). 

The following reagent, a 0.25 m solution of 2,4-dinitrophenylhydrazine, may be used for the preparation of derivatives of keto compounds. Dissolve 25 g of 2,4-... 

Carbon-14 content is measured by specially designed gas proportional counters (7. Aerosol samples are first converted to CO2 by combustion in a macroscale version of the thermal evolution technique. A clam shell oven was used to heat the sample for sequential evolution of organic and elemental carbon under equivalent conditions. Due to the possibility of thermal gradients, conditions in the macroscale apparatus were adjusted to produce the same recoveries of total carbon (yg C per cm of filter area) as for the microscale apparatus. Carbon-14 data are reported as % contemporary carbon based on the 1978 1 C02 content in the atmosphere. Aldehyde data referred to in this paper were obtained by impinger sampling in dinitrophenylhydrazine/acetonitrile solution and analysis of the derivatives by HPLC with UV detection (12). Olefin measurements were made by a specially designed ozone-chemiluminescence apparatus (13) difficulties in calibration accuracy and background drift with temperature limit its use to inferences of relative reactive hydrocarbon levels. 

The reaction of an aldehyde or a ketone with 2,4-dinitrophenylhydrazine produces a 2,4-dinitrophenylhydrazone derivative. This reaction is also used as a test for the presence of an aldehyde or ketone. A drop or two of a suspected aldehyde or ketone is added to a solution of 2,4-dinitrophenylhydrazine in ethanol and water. The formation of a precipitate, usually orange or red, of the derivative indicates that the unknown is an aldehyde or ketone ... 

Dinitrophenylhydrazine is frequently used for making derivatives of ketones and aldehydes because the products (2,4-dinitrophenylhydrazones, called 2,4-DNP derivatives) are even more likely than the phenylhydrazones to be solids with sharp melting points. Propose a mechanism for the reaction of acetone with 2,4-dinitrophenylhydrazine in a mildly acidic solution. 

Dinitrophenylhydrazine, 2,4-(N02)2C6H3NHNH2 Reacts with aldehydes and ketones to yield 2,4-DNPs that serve as useful crystalline derivatives (Section 19.8). 

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