Methylation

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methylation

[‚meth·ə′lā·shən]
(organic chemistry)
A chemical process for introducing a methyl group (CH3‒) into an organic compound.

Methylation

 

the replacement of a hydrogen, metal, or halogen atom by a methyl group,—CHs; it is effected by the action of various methylating agents—for example, methyl iodide, CH3I; dimethyl sulfate, (CH3O)2SO2; methylsulfuric acid, CH3OSO3H; methyl esters of organic sulfo acids; methanol, CHjOH; and dimethyl ether, (CH3)2O. Methylation is widely used in organic synthesis in industry. For example, methylation with dimethyl sulfate is used in the synthesis of pharmaceuticals (for example, metapyrin); amidopyrine is prepared by methylation with formaldehyde and a reducing agent, usually formic acid.

Aromatic hydrocarbons are readily methylated by the action of methyl chloride or dimethyl ether in the presence of AlCl3. Methylaniline and dimethylaniline are prepared industrially by methylation of aniline with methanol over A12O3 at high temperatures:

Methylation with diazomethane is widely used to produce methyl esters of carboxylic acids under laboratory conditions, according to the formula

R—COOH + CH2N2→RCOOCH3 + N2

B. L. DIATKIN

References in periodicals archive ?
We conducted a prospective case--cohort study nested in a large prospective cohort to assess associations of arsenic exposure from drinking water and arsenic methylation capacity, indicated using relative distribution of urinary arsenic metabolites, with CVD risk.
The effects associated with higher levels of well-water arsenic and lower methylation capacity on heart disease risk were at least additive.
2011) also reported associations between dietary intake of several nutrients (assessed using a modified 24-hr recall) and As methylation capacity.
The intracellular AdoMet/AdoHcy ratio has been used as a predictor of cellular methylation capacity.
To better understand the difference in methylation capacity between males and females, we repeated the multiple regression analyses stratified by sex (Table 4).
The relationship between methylation capacity and skin lesions needs further investigation.
Determinants of inorganic arsenic methylation capacity among residents of the Lanyang Basin, Taiwan: arsenic and selenium exposure and alcohol consumption.
The relative distribution of urinary In-As, MMA, and DMA is still considered an adequate indicator of methylation capacity after exposure to In-As, although the interpretation of the findings in terms of detoxification versus toxification is currently an area of active investigation (Styblo 2002; Vahter and Concha 2001).
methyl] and MMA/DMA were calculated as metabolic indices to measure the stepwise methylation capacity.
If genetic factors contribute to arsenic methylation capacity, family studies should demonstrate that siblings have a higher correlation of methylation activity than their parents.
Epidemiological Studies on Inorganic Arsenic Methylation Capacity and Inorganic Arsenic Induced Health Effects Among Residents in the Blackfoot Disease Endemic Area and Lanyang Basin in Taiwan [PhD Thesis].