An alkyl group, generally abbreviated with the symbol R, is a functional group or side-chain that, like an alkane, consists solely of single-bonded carbon and hydrogen atoms, for example a methyl or ethyl group.

Examples of benzene compounds with just one substituent are phenol, which carries a hydroxyl group, and toluene with a methyl group.

For example, three isomers exist for cresol because the methyl group and the hydroxyl group can be placed next to each other ( ortho ), one position removed from each other ( meta ), or two positions removed from each other ( para ).

Xylenol has two methyl groups in addition to the hydroxyl group, and, for this structure, 6 isomers exist.

In theory one can describe compounds that contain the methyl group, with relatively large bond polarity between the carbon and non-hydrogen atom, as salts of this anion ; however in truth most such compounds, if not all, are actually covalent.

The nucleobases are classified into two types: the purines, A and G, being fused five-and six-membered heterocyclic compounds, and the pyrimidines, the six-membered rings C and T. A fifth pyrimidine nucleobase, uracil ( U ), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring.

Each moiety may contain additional functional groups -- for example, methyl para-hydroxybenzoate contains a phenol functional group within the acyl moiety.

Different styles of drawing a methyl group ( highlighted in < span style =" color: blue ;"> blue </ span >)

The reactivity of a methyl group depends on the adjacent substituents.

For example, in organic compounds, the methyl group resists attack by even the strongest acids.

The oxidation of a methyl group occurs widely in nature and industry.

For example, permanganate often converts a methyl group to a carboxyl (- COOH ) group, e. g. the conversion of toluene to benzoic acid.

Demethylation ( the transfer of the methyl group to another compound ) is a common process, and reagents that undergo this reaction are called methylating agents.

When placed in benzylic or allylic positions, the C-H bond strength is decreased, and the reactivity of the methyl group increases.

One manifestation of this enhanced reactivity is the photochemical chlorination of the methyl group in toluene to give benzyl chloride.

* The methyl group that makes morphine into codeine can be removed or added back, or replaced with another functional group like ethyl and others to make codeine analogues of morphine-derived drugs and vice versa.

* Attachment, removal or modification of functional groups to positions 3 and / or 6 ( dihydrocodeine and related, hydrocodone, nicomorphine ); in the case of moving the methyl functional group from position 3 to 6, codeine becomes heterocodeine, which is 72 times stronger, and therefore six times stronger than morphine

Illustrative of the many functions of the B < sub > 12 </ sub >- dependent enzymes, the MTR enzyme catalyzes the transfer of a methyl group from a nitrogen on N5-methyl-tetrahydrofolate to the sulfur of homocysteine to produce methionine.

Aluminum can be deposited from tri-isobutyl aluminium ( TIBAL ), tri ethyl / methyl aluminum ( TEA, TMA ), or dimethylaluminum hydride ( DMAH ), but physical vapor deposition methods are usually preferred.

Using this diazomethane, mixtures of carboxylic acids can be converted to their methyl esters in near quantitative yields, e. g., for analysis by gas chromatography.

For quarantine purposes, insect pests can also be eliminated by fumigation with methyl bromide or aluminium phosphine, vapour heat, forced hot air, hot water dipping, or cold treatment.

Certain methyl groups can be deprotonated.

Extremely minor chemical changes such as the addition of a single methyl group to a binding partner can sometimes suffice to nearly eliminate binding ; for example, the aminoacyl tRNA synthetase specific to the amino acid valine discriminates against the very similar side chain of the amino acid isoleucine.

The fruit of most species of Capsicum contains capsaicin ( methyl vanillyl nonenamide ), a lipophilic chemical that can produce a strong burning sensation ( pungency or spiciness ) in the mouth of the unaccustomed eater.

Branches or cross-links in the polymer chain can be introduced by using silane precursors with more acid-forming groups and fewer methyl groups, such as methyltrichlorosilane.

Similarly, precursors with three methyl groups can be used to limit molecular weight, since each such molecule has only one reactive site and so forms the end of a siloxane chain.

** ortho-xylene-both methyl groups can be oxidized to form ( ortho -) phthalic acid

** para-xylene-both methyl groups can be oxidized to form terephthalic acid

Arginine can be methylated once ( monomethylated arginine ) or twice, with either both methyl groups on one terminal nitrogen ( asymmetric dimethylated arginine ) or one on both nitrogens ( symmetric dimethylated arginine ) by peptidylarginine methyltransferases ( PRMTs ).

The phenolic compounds 6 '- O -( 3, 4-dihydroxy benzoyl )- beta-D-glucopyranosyl ester, 4-O-beta-d-glucopyranoside-3-hydroxy methyl benzoate, methyl benzoate, hypogallic acid, caffeic acid, paeoniflorin and pikuroside can be isolated from Salvinia molesta.

The most common form uses methanol ( converted to sodium methoxide ) to produce methyl esters ( commonly referred to as Fatty Acid Methyl Ester-FAME ) as it is the cheapest alcohol available, though ethanol can be used to produce an ethyl ester ( commonly referred to as Fatty Acid Ethyl Ester-FAEE ) biodiesel and higher alcohols such as isopropanol and butanol have also been used.

Esters with larger alkoxy groups can be made from methyl or ethyl esters in high purity by heating the mixture of ester, acid / base, and large alcohol and evaporating the small alcohol to drive equilibrium.

Terpenoids can be thought of as modified terpenes, wherein methyl groups have been moved or removed, or oxygen atoms added.

AQIS conducts methyl bromide fumigation certification for both domestic and foreign fumigators who can then fumigate containers destined for Australia.

This interaction redistributes the positive charge and leads to the deprotonation of one nitrogen group, which can then make a nucleophilic attack on the methyl group of SAM.

When left on the tongue, the anaerobic respiration of such bacteria can yield either the putrescent smell of indole, skatole, polyamines, or the " rotten egg " smell of volatile sulfur compounds ( VSCs ) such as hydrogen sulfide, methyl mercaptan, Allyl methyl sulfide, and dimethyl sulfide.

Chain-growth polymers like poly ( methyl methacrylate ) can be degraded by thermolysis at high temperatures to give monomers, oils, gases and water.

This unwanted side-effect has caused many common volatile brominated organics like methyl bromide, a pesticide that was formerly a large industrial bromine consumer, to be abandoned.

While standard ' superglue ' is 100 % ethyl cyanoacrylate, many custom formulations ( e. g .,, 91 % ECA, 9 % poly ( methyl methacrylate ), < 0. 5 % hydroquinone, and a small amount of organic sulfonic acid and variations on the compound N-butyl-cyanoacrylate's for medical applications ) have come to be used for specific applications.

These refrigerants were considered at the time to be less harmful than the commonly-used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide.

Example: CH < sub > 3 </ sub > SH would be methyl mercaptan, just as CH < sub > 3 </ sub > OH is called methyl alcohol.

Methylation is a form of alkylation with, to be specific, a methyl group, rather than a larger carbon chain, replacing a hydrogen atom.

For example a carboxylate may be methylated on oxygen to give a methyl ester, an alkoxide salt RO < sup >−</ sup > may be likewise methylated to give an ether, ROCH < sub > 3 </ sub >, or a ketone enolate may be methylated on carbon to produce a new ketone.

Usually, methyl groups are present at the carbons C-10 and C-13 – an alkyl side-chain at carbon C-17 may also be present.