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Diazomethane
 
 
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Diazomethane is the chemical compound CH2N2. In the pure form at room temperature, it is a yellow
Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, but does not significantly stimulate the S cone cells; that is, light with much red and green but not very much blue....
 gas
Gas

In physics, a gas is a state of matter, consisting of a collection of particles without a definite shape or volume that are in more or less random motion....
, but it is almost universally used as a solution in diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
. It is one of the more common diazo compounds. It is also toxic and potentially explosive.
ub>2N2 is usually prepared as a solution
Solution

In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent....
 in diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
 and used for converting carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s into their methyl ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
s or into their homologues
Homologous series

In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass ....
 (see Arndt-Eistert synthesis
Arndt-Eistert synthesis

The Arndt-Eistert synthesis is a series of chemical reactions designed to convert a carboxylic acid to a higher carboxylic acid homologue and is considered a homologization process....
).






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Diazomethane is the chemical compound CH2N2. In the pure form at room temperature, it is a yellow
Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, but does not significantly stimulate the S cone cells; that is, light with much red and green but not very much blue....
 gas
Gas

In physics, a gas is a state of matter, consisting of a collection of particles without a definite shape or volume that are in more or less random motion....
, but it is almost universally used as a solution in diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
. It is one of the more common diazo compounds. It is also toxic and potentially explosive.

Preparation

CH2N2 is usually prepared as a solution
Solution

In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent....
 in diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
 and used for converting carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s into their methyl ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
s or into their homologues
Homologous series

In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass ....
 (see Arndt-Eistert synthesis
Arndt-Eistert synthesis

The Arndt-Eistert synthesis is a series of chemical reactions designed to convert a carboxylic acid to a higher carboxylic acid homologue and is considered a homologization process....
). In the Buchner-Curtius-Schlotterbeck reaction (1885) diazomethane reacts with an aldehyde
Aldehyde

An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom bonded to a hydrogen atom and double bond to an oxygen atom , is called the aldehyde group....
 to form ketone
Ketone

In organic chemistry, a ketone is a type of organic compound which contains a carbonyl group bonded to two other carbon atoms in the form:Neither of the substituents R1 and R2 may be equal to hydrogen ....
s. Diazomethane is also frequently used as a carbene
Carbene

In chemistry, a carbene is a highly reactive organic molecule containing a carbon atom with six valence electrons and having the general formula: R1R2C: ....
 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
Guanidine

Guanidine is a crystalline compound of strong alkalinity formed by the oxidation of guanine. It is used in the manufacture of plastics and explosives....
. Diazald in a solution of diglyme
Diglyme

Diglyme, or bis ether, is a solvent with a high boiling point. It is an organic compound which is the dimethyl ether of diethylene glycol. It is a clear, colorless liquid with a slight ether-like odor....
 and diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
 reacts with a warm aqueous solution of sodium hydroxide
Sodium hydroxide

Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
 and the generated CH2N2 is collected by distillation
Distillation

Distillation is a method of separation process mixtures based on differences in their Volatility in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
. Diazomethane is liberated from a solution of MNNG in diethyl ether
Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
 by addition of aqueous potassium hydroxide
Potassium hydroxide

Potassium hydroxide is the inorganic compound with the formula potassiumhydroxide. Along with sodium hydroxide, this colourless solid is a prototypical "strong base"....
 at low temperatures.
Diazomethane Precursors
Another possible way of the diazomethane synthesis is the basic hydrolysis of N-Nitroso-N-methylurea
N-Nitroso-N-methylurea

N-Nitroso-N-methylurea is a highly potent carcinogen, mutagen, and teratogen. MNU is an alkylating agent, and exhibits its toxicity by transferring its methyl group to nucleobases in nucleic acids....
.

CH2N2 reacts with basic solutions of 2H2O to give the deuterated derivative C2H2N2.

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, e, is 7.2.

Related compounds

Many substituted derivatives of diazomethane have been prepared:
  • The very stable (CF3)2CN2 (b.p. 12–13 °C),
  • Ph2CN2 (m.p. 29–30 °C).
  • (CH3)3SiCHN2, which is commercially available as a solution and is as effective as CH2N2 for methylation.
  • PhC(H)N2, a red liquid b.p.< 25 °C at 0.1 mm Hg.


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. 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.

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