Toxicity diazomethane

CAUTION Carry out the preparation in an efficient fume cupboard (hood) since diazomethane is very toxic. 

Diazomethane. CA UTION. Diazomethane is highly toxic its pre paration should be carried out only in a fume cupboard (hood) provided with a powerful exhaust system. The use of a screen of safely glass is recommended. 

Diazomethane is a yellow gas that is toxic and explosive but that may be handled safely in solution in ether. It reacts immediately with an acid to liberate nitrogen and form the methyl ester. Its reaction with alcohols to form methyl esters requires catalysis by a Lewis acid. The procedures illustrate the use of this reagent as a methylating agent (see Chapter 17, Section III, for preparation of diazomethane). 

This experiment must be carried out in an efficient hood since diazomethane is highly toxic. Also, a safety screen is recommended. (See Chapter 17, Section III for other precautions.)... 

The main drawback to this reaction is the toxicity of diazomethane and some of its precursors. Diazomethane is also potentially explosive. Trimethylsilyldia-zomethane is an alternative reagent,42 which is safer and frequently used in preparation of methyl esters from carboxylic acids.43 Trimethylsilyldiazomethane also O-methylates alcohols.44 The latter reactions occur in the presence of fluoroboric acid in dichloromethane. 

Dialkylation occurs if a stronger base (NaOH) and dimethyl sulfate is used. Entry 18 is a typical diazomethane methylation of a carboxylic acid. The toxicity of diazomethane... 

Carbenes from Diazo Compounds. Decomposition of diazo compounds to form carbenes is a quite general reaction that is applicable to diazomethane and other diazoalkanes, diazoalkenes, and diazo compounds with aryl and acyl substituents. The main restrictions on this method are the limitations on synthesis and limited stability of the diazo compounds. The smaller diazoalkanes are toxic and potentially explosive, and they are usually prepared immediately before use. The most general synthetic routes involve base-catalyzed decomposition of V-nitroso derivatives of amides, ureas, or sulfonamides, as illustrated by several reactions used for the preparation of diazomethane. 

Despite the higher selectivity of enzymatic methyl transfer over chemical methylation, where toxic or hazardous reagents are often employed, such as methyl sulfonate and diazomethane, the synthetic applications of these enzymes have been largely ignored primarily as a result of high costs associated with the cofactor SAM. Recent efforts have been directed to in vivo methylation, where SAM may be regenerated inside cells. For example, methyl benzoate production was engineered in recombinant Saccharomyces cerevisiae and in vivo... 

Diazomethane is one of the most versatile and useful reagents in organic chemistry in spite of the fact that it is very highly toxic and dangerously explosive and can not be stored without decomposition. 

It was important to determine whether the fluorine atom must be attached directly to the phosphorus atom in order to produce phosphorofluoridate-like activity. For this purpose we treated the toxic di-sec.-butyl phosphorofluoridate1 with diazomethane and obtained a compound which was undoubtedly di- ec.-butyl fluoromethylphosphonate (XIX). Unlike the parent phosphorofluoridate, the fluoromethylphosphonate was only slightly toxic and produced negligible myosis. (It may be mentioned here that thionyl chloride and carbonyl chloride were converted by means of diazomethane into bis-(chloromethyl)-sulphoxide and S-dichloroacetone respectively.)... 

Kataoka (1997) describes a method for the analysis of 21 protein amino acids and 33 nonprotein amino acids with NPD detection. One disadvantage of this method is the use of diazomethane, which is explosive and toxic (Kataoka, 1997). A method for homocysteine with GC-FID analysis uses a one-step derivatization with ethyl chloroformate and an extraction procedure (Husek et al., 2003). 

Caution Because of the toxic nature of chlorine and diazomethane and the lachrymatory properties of chloromcthanesulfonyl chloride, both steps of this preparation should be carried out in a well-ventilated hood. Diazomethane is also explosive follow the directions for its handling given in earlier volumes. ... 

Diazomethane. Diazomethane is a yellow, toxic gas. You must never use ground glass joints or cracked or chipped glassware as this will trigger an explosion. 1 will give an intermediate first. 

W-Methyl-A/ -nitroso-p-toluenesulfonamide (MNTS) is an important precursor for the production of diazomethane. Diazomethane is then further converted to a range of useful molecules in the pharmaceutical and fine chemical industry [69]. Production of MNTS is a highly exothermic process and includes the presence of the extremely toxic materials. Stark et al. [70] have explored the application of microreactor technology for the production of this industrially valuable material, assuming that due to the efficient heat exchange and the closed system, microflow conditions provide a safer environment for these hazards. 

Caution Diazomethane shouid be handled in an efficient fume hood behind a protection shield because of its toxicity and the possibility of explosions. 

Caution Diazomethane is very toxic therefore the operations must be carried out in a well-ventilated hood. 

Carbenes are divalent carbon compounds, also known as methylene. They have neutral carbons with a lone pair of electrons, and are highly reactive. Methylene can be prepared by heat or light initiated decomposition of diazomethane (explosive and toxic gas). 

Caution Diazomethane is toxic and explosive. The operation must be carried out in a good hood with an adequate shield (.see Note 1) ... 

Both the toxicity and explosion hazards associated with diazomethane are discussed by Gutsche.4... 

Diazomethane, CH2N2, is a toxic, highly reactive, potenlially explosive gas [18]. 

The Phoenix diazomethane process can produce over 200 ty of chloroketone with an overall yield of 90% and in very high purity. This demonstrates a remarkable use of a highly explosive and toxic material (exposure limit of 0.2 ppm averaged over 8h) controlled by conhnuous generation and reaction. Thus, over 60ty" diazomethane are consumed per annum, but the maximum accumulated at any time is less than 80 g. 

Phenyldiazomethane, 1, 834. A new method for preparation of this (and other aryl-diazomethanes) involves a vacuum pyrolysis of the sodium salt of benzaldehyde tosylhydrazone, a method introduced for carrying out the Bamford-Stevens reaction. The yield is 80%, the highest yield yet reported. Another advantage is that the reagent is obtained free from solvents. The pyrolysis can also be coitducted in ethylene glycol at 80° with extraction of the aryldiazomethane into hexane.1 Caution All diazo compounds arc highly toxic and potentially explosive. 

Precursor of diazomethane, a highly toxic and unpredictably explosive gas. Possibly a carcinogen. Read details carefully before preparation. Reactions with and preparation of diazomethane should be carried out in a fume hood and behind a sturdy safety shield. Rough glass surfaces and strong sunlight are known to initiate detonation. 

Diazomethane is very toxic its preparation should be carried out only in a well-ventilated hood. Individuals differ in their susceptibility some develop symptoms similar to asthma from very small concentrations, whereas others notice no ill effects from much larger quantities. The use of a safety screen is also recommended. 

---