2,4-Dinitrophenylhydrazine (2,4-DNPH or DNPH) is the organic compound C6H3(NO2)2NHNH2. 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.
DNPH is a reagent in instructional laboratories on qualitative organic analysis. Brady's reagent or Borche's reagent, is prepared by dissolving DNPH in a solution containing methanol and some concentrated sulfuric acid. This solution is used to detectketones and aldehydes. A positive test is signalled by the formation of a yellow, orange or red precipitate of the dinitrophenylhydrazone. Aromatic carbonyls give red precipitates whereas aliphatic carbonyls give more yellow color.[2] The reaction between DNPH and a generic ketone to form a hydrazone is shown below:
This reaction is, overall, a condensation reaction as two molecules joining together with loss of water. Mechanistically, it is an example of addition-elimination reaction: nucleophilic addition of the -NH2 group to the C=O carbonyl group, followed by the elimination of a H2O molecule:[3]
X-ray structure of DNP-derived hydrazone of benzophenone. Selected parameters: C=N, 128 pm; N-N, 1.38 pm, N-N-C(Ar), 119[4]
When 3-heptanone is added to a solution of 2,4-DNPH and heated, an orange-red precipitate forms.
DNP-derived hydrazones have characteristic melting points, facilitating identification of the carbonyl. In particular, the use of DNPH was developed by Brady and Elsmie.[5] Modern spectroscopic and spectrometric techniques have superseded these techniques.
DNPH does not react with other carbonyl-containing functional groups such as carboxylic acids, amides, and esters, for which there is resonance-associated stability as a lone-pair of electrons interacts with the p orbital of the carbonyl carbon resulting in increased delocalization in the molecule. This stability would be lost by addition of a reagent to the carbonyl group. Hence, these compounds are more resistant to addition reactions. Also, with carboxylic acids, there is the effect of the compound acting as a base, leaving the resulting carboxylate negatively charged and hence no longer vulnerable to nucleophilic attack.
Safetyedit
Dry DNPH is friction and shock sensitive. For this reason, it’s supplied damp or ‘wetted’ when a school purchases it from a chemical supplier.[6] If DNPH is stored improperly and left to dry out, it can become explosive. It is an artificial uncoupler of the electron transport chain (ETC).[7]
^Allen, C. F. H. (1933). "2,4-Dinitrophenylhydrazine". Organic Syntheses. 13: 36. doi:10.15227/orgsyn.013.0036.
^Mohrig, Jerry R.; Hammond, Christina Noring; Morrill, Terence C.; Neckers, Douglas C. (1998). Experimental Organic Chemistry: A Balanced Approach, Macroscale and Microscale. New York: W.H. Freeman and Company. p. 530. ISBN0-7167-2818-4.
^Adapted from Chemistry in Context, 4th Edition, 2000, Graham Hill and John Holman
^Brady, Oscar L.; Elsmie, Gladys V. (1926). "The use of 2:4-dinitrophenylhydrazine as a reagent for aldehydes and ketones". Analyst. 51 (599): 77–78. Bibcode:1926Ana....51...77B. doi:10.1039/AN9265100077.
^"What is 2,4-DNPH and Why Are Schools Carrying Out Controlled Explosions?". Compound Interest. 7 November 2016. Retrieved 26 October 2022.
^"Bomb disposal squads detonate chemical stocks in British schools". The Guardian. 2 November 2016. Retrieved 19 March 2018.
January 01, 1970
dinitrophenylhydrazine, dnph, dnph, organic, compound, c6h3, 2nhnh2, dnph, orange, solid, substituted, hydrazine, solid, relatively, sensitive, shock, friction, this, reason, dnph, usually, handled, powder, dnph, precursor, drug, sivifene, names, preferred, iu. 2 4 Dinitrophenylhydrazine 2 4 DNPH or DNPH is the organic compound C6H3 NO2 2NHNH2 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 2 4 Dinitrophenylhydrazine Names Preferred IUPAC name 2 4 Dinitrophenyl hydrazine Other names 2 4 DNPH2 4 DNPDNPHBrady s reagentBorche s reagent Identifiers CAS Number 119 26 6 Y 3D model JSmol Interactive image ChEBI CHEBI 66932 Y ChEMBL ChEMBL352799 Y ChemSpider 3001507 Y ECHA InfoCard 100 003 918 EC Number 204 309 3 KEGG C11283 Y PubChem CID 3772977 UNII 1N39KD7QPJ CompTox Dashboard EPA DTXSID2059485 InChI InChI 1S C6H6N4O4 c7 8 5 2 1 4 9 11 12 3 6 5 10 13 14 h1 3 8H 7H2 YKey HORQAOAYAYGIBM UHFFFAOYSA N YInChI 1 C6H6N4O4 c7 8 5 2 1 4 9 11 12 3 6 5 10 13 14 h1 3 8H 7H2Key HORQAOAYAYGIBM UHFFFAOYAM SMILES c1cc c cc1 N O O N O O NN Properties Chemical formula C6H6N4O4 Molar mass 198 14 g mol Appearance Red or orange powder Melting point 198 to 202 C 388 to 396 F 471 to 475 K dec Solubility in water Slight Hazards Occupational safety and health OHS OSH Main hazards Flammable possibly carcinogenic GHS labelling Pictograms Signal word Warning Hazard statements H228 H302 H319 Precautionary statements P210 P240 P241 P264 P270 P280 P301 P312 P305 P351 P338 P330 P337 P313 P370 P378 P501 Safety data sheet SDS MSDS Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Synthesis 2 DNP test 3 Safety 4 See also 5 ReferencesSynthesis editIt can be prepared by the reaction of hydrazine sulfate with 2 4 dinitrochlorobenzene 1 nbsp DNP test editDNPH is a reagent in instructional laboratories on qualitative organic analysis Brady s reagent or Borche s reagent is prepared by dissolving DNPH in a solution containing methanol and some concentrated sulfuric acid This solution is used to detect ketones and aldehydes A positive test is signalled by the formation of a yellow orange or red precipitate of the dinitrophenylhydrazone Aromatic carbonyls give red precipitates whereas aliphatic carbonyls give more yellow color 2 The reaction between DNPH and a generic ketone to form a hydrazone is shown below RR C O C6H3 NO2 2NHNH2 C6H3 NO2 2NHN CRR H2O This reaction is overall a condensation reaction as two molecules joining together with loss of water Mechanistically it is an example of addition elimination reaction nucleophilic addition of the NH2 group to the C O carbonyl group followed by the elimination of a H2O molecule 3 nbsp X ray structure of DNP derived hydrazone of benzophenone Selected parameters C N 128 pm N N 1 38 pm N N C Ar 119 4 nbsp When 3 heptanone is added to a solution of 2 4 DNPH and heated an orange red precipitate forms DNP derived hydrazones have characteristic melting points facilitating identification of the carbonyl In particular the use of DNPH was developed by Brady and Elsmie 5 Modern spectroscopic and spectrometric techniques have superseded these techniques DNPH does not react with other carbonyl containing functional groups such as carboxylic acids amides and esters for which there is resonance associated stability as a lone pair of electrons interacts with the p orbital of the carbonyl carbon resulting in increased delocalization in the molecule This stability would be lost by addition of a reagent to the carbonyl group Hence these compounds are more resistant to addition reactions Also with carboxylic acids there is the effect of the compound acting as a base leaving the resulting carboxylate negatively charged and hence no longer vulnerable to nucleophilic attack Safety editDry DNPH is friction and shock sensitive For this reason it s supplied damp or wetted when a school purchases it from a chemical supplier 6 If DNPH is stored improperly and left to dry out it can become explosive It is an artificial uncoupler of the electron transport chain ETC 7 See also editTollens reagent Fehling s reagent Schiff testReferences edit Allen C F H 1933 2 4 Dinitrophenylhydrazine Organic Syntheses 13 36 doi 10 15227 orgsyn 013 0036 Mohrig Jerry R Hammond Christina Noring Morrill Terence C Neckers Douglas C 1998 Experimental Organic Chemistry A Balanced Approach Macroscale and Microscale New York W H Freeman and Company p 530 ISBN 0 7167 2818 4 Adapted from Chemistry in Context 4th Edition 2000 Graham Hill and John Holman Tameem Abdassalam Abdelhafiz Salhin Abdussalam Saad Bahruddin Rahman Ismail Ab Saleh Muhammad Idiris Ng Shea Lin Fun Hoong Kun 2006 Benzophenone 2 4 dinitrophenylhydrazone Acta Crystallographica Section E 62 12 o5686 o5688 doi 10 1107 S1600536806048112 Brady Oscar L Elsmie Gladys V 1926 The use of 2 4 dinitrophenylhydrazine as a reagent for aldehydes and ketones Analyst 51 599 77 78 Bibcode 1926Ana 51 77B doi 10 1039 AN9265100077 What is 2 4 DNPH and Why Are Schools Carrying Out Controlled Explosions Compound Interest 7 November 2016 Retrieved 26 October 2022 Bomb disposal squads detonate chemical stocks in British schools The Guardian 2 November 2016 Retrieved 19 March 2018 Retrieved from https en wikipedia org w index php title 2 4 Dinitrophenylhydrazine amp oldid 1198515973, wikipedia, wiki, book, books, library,
