Home > Diazomethane
 | | | |
Learn more about "Diazomethane"
|
|
|
Diazomethane{{Chembox new
| Name = Diazomethane
| ImageFile = diazomethane.png
| ImageSize = 140px
| ImageName = Diazomethane
| ImageFile1 = Diazomethane-3D-vdW.png
| ImageSize1 = 160px
| ImageName1 = Diazomethane
| IUPACName = Diazomethane
| Section1 =
| Section2 =
| Section3 =
| Section7 =
| Section8 =
}}
Diazomethane is the chemical compound CH2N2. In the pure form at room temperature, it is a yellow gas, but it is almost universally used as a solution in diethyl ether. It is one of the more common diazo compounds. It is also toxic and potentially explosive.
Preparation[J. A. Moore; D. E. Reed “Diazomethane” Organic Syntheses Collective Volume 5, page 351]
CH2N2 is usually prepared as a solution in diethyl ether and used for converting carboxylic acids into their methyl esters or into their homologous series|homologues (see Arndt-Eistert synthesis). In the '''Buchner-Curtius-Schlotterbeck reaction''' (1885) diazomethane reacts with an aldehyde to form ketones. Diazomethane is also frequently used as a carbene source. It readily takes part in 1,3-dipolar cycloaddition reactions. Diazomethane is prepared in the laboratory at mmol scale from precursors such as '''Diazald''' or N-methyl-N-nitroso-p-toluenesulfonamide and '''MNNG''' or 1-methyl-3-nitro-1-nitrosoguanidine. Diazald in a solution of diglyme and diethyl ether reacts with a warm aqueous solution of sodium hydroxide and the generated CH2N2 is collected by distillation. Diazomethane is liberated from a solution of MNNG in diethyl ether by addition of aqueous potassium hydroxide at low temperatures.
Another possible way of the diazomethane synthesis is the basic hydrolysis of N-Nitroso-N-methylurea.
CH2N2 reacts with basic solutions of 2H2O to give the deuterated derivative C2H2N2.[P. G. Gassman and W. J. Greenlee “Dideuterodiazomethane” Organic Syntheses Collective Volume 6, page 432.]
Assay
The concentration of CH2N2 can be determined in either of two convenient ways. It can be treated with an excess of benzoic acid in cold Et2O. Unreacted benzoic acid is then assayed using titration with standard NaOH. Alternatively, the concentration of CH2N2 in Et2O can be determined spectrophotometrically at 410 nm where its extinction coefficient, ε, is 7.2.
Related compounds
Many substituted derivatives of diazomethane have been prepared:
- The very stable (CF3)2CN2 (b.p. 12–13 °C),[W. J. Middleton; D. M. Gale “Bis(Trifluoromethyl))diazomethane” Organic Syntheses Collective Volume 6, page 161]
- Ph2CN2 (m.p. 29–30 °C).[L. I. Smith, K. L. Howard “Diphenyldiazomethane” Organic Syntheses Collective Volume 3, page 351]
- (CH3)3SiCHN2, which is commercially available as a solution and is as effective as CH2N2 for methylation.[T. Shioiri, T. Aoyama, S. Mori “Trimethylsilyldiazomethane” Organic Syntheses Collected Volume, Volume 8, page 612.]
- PhC(H)N2, a red liquid b.p.< 25 °C at 0.1 mm Hg.[X. Creary “Tosylhydrazone Salt Pyrolyses: Phenydiazomethanes” Organic Syntheses, Coll. Vol. 7, p.438 (1990); Vol. 64, p.207 (1986).]
Safety
Diazomethane is toxic by inhalation or by contact with the skin or eyes (TLV 0.2ppm). Symptoms include chest discomfort, headache, weakness and, in severe cases, collapse.[Muir, GD (ed.) 1971, ''Hazards in the Chemical Laboratory'', The Royal Institute of Chemistry, London.] CH2N2 may explode when in contact with ground-glass joints or when heated to about 100.0 °C. Consequently specialized, scratch-free glassware and a blast shield should be employed for its use.
References
External links
- MSDS diazomethane
- Sigmaaldrich technical bulletin
- The Buchner-Curtius-Schlotterbeck reaction @ Institute of Chemistry, Skopje, Macedonia
*
Category:Diazo compounds
Category:Methylating agents
Category:IARC Group 3 carcinogens
Category:Nitrogen compounds
Related Images- Diazomethane laboratory preparation
- Diazomethane precursors
Sources: StartLearningNow, Wikipedia | Usage license: GNU FDL
 |
Welcome to Start Learning Now.
Explore to your heart's content, and we hope you enjoy reading the material we
have assembled for you here! |
 |
| | | | |
Related News
|
|
Further Resources
|
|
Related Resources
search
|
|
