Benzyl

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Benzyl

In organic chemistry

Organic chemistry

Organic chemistry is a discipline within chemistry which involves the science study of the structure, properties, composition, chemical reaction, and preparation of chemical compounds that contain carbon....
, benzyl is the term used to describe the substituent

Substituent

In organic chemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon. The suffix -yl is used when naming organic compounds that contain a substituent....
or molecular fragment possessing the structure C₆H₅CH₂-. The abbreviation "Bn" is frequently used to denote benzyl moieties in nomenclature and structural depictions of chemical compounds.

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In organic chemistry

Organic chemistry

Substituent

Benzyl alcohol

Benzyl alcohol is an organic compound with the formula C6H5CH2OH. The benzyl group is often abbreviated "Bn", thus benzyl alcohol is denoted as BnOH....
can be represented as BnOH. This abbreviation is not to be confused with "Bz", which is the abbreviation for the benzoyl

Benzoyl

In organic chemistry, benzoyl is the acyl of benzoic acid, with structure C6H5CO-. It should not be confused with benzyl, which is the radical or ion formed from the removal of one of the methyl hydrogens of toluene ....
group C₆H₅C(O)-.

The term benzyl is also used in reference to the carbocation

Carbocation

A carbocation is an ion with a positively-charged carbon atom. The charged carbon atom in a carbocation is a "sextet", i.e. it has only six electrons in its outer Electron shell#Valence shell instead of the eight valence electrons that ensures maximum stability ....
, anion, and free radical moieties featuring a benzene

Benzene

Benzene, or benzol, is an organic compound chemical compound and a known carcinogen with the molecular formula Carbon6Hydrogen6....
ring attached to a CH₂ group, in which the CH₂ group bears a positive charge, a negative charge, or a single unpaired electron respectively.

In substituent nomenclature, benzyl and phenyl are commonly confused. Benzyl can be seen as a phenyl attached to a CH₂ before attaching to the parent compound.

The term benzylic refers to the position on a carbon skeleton next to a phenyl or other aromatic ring. Because of the aromatic neighbor, benzylic positions are endowed with special reactivity, as in oxidation, free radical halogenation

Free radical halogenation

In organic chemistry, free radical halogenation is a type of halogenation. This chemical reaction is typical of alkanes and alkyl-substituted aromatics under application of heat or UV light....
, or hydrogenolysis

Hydrogenolysis

Hydrogenolysis is a chemical reaction whereby a carbon-carbon or carbon-heteroatom single bond is cleaved or undergoes "lysis" by hydrogen. The heteroatom may vary, but it usually is oxygen, nitrogen, or sulfur....
.

Benzyl protective groups

Benzyl groups are frequently used in organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
as protective group for alcohol

Alcohol

In chemistry, an alcohol is any organic compound in which a hydroxyl Functional group is bound to a carbon atom of an alkyl or substituted alkyl group....
s and 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.

Two common methods for benzyl ether protection:

reaction of alcohol with benzyl bromide and a strong base such as sodium hydride
Sodium hydride

Sodium hydride is the chemical compound with the formula NaH. It is primarily used as a strong base in organic synthesis. NaH is representative of the saline hydrides, meaning it is a salt-like hydride, composed of Na+ and H- ions, in contrast to the more molecular hydrides such as borane, methane, ammonia and water....
as in a Williamson ether synthesis
Williamson ether synthesis

The Williamson ether synthesis is an organic reaction, forming an ether from a organohalide and an alcohol. This reaction was developed by Alexander William Williamson in 1850 ....
reaction of alcohol with an imidate such as benzyl trichloroacetimidate (C₆H₅CH₂OC(CCl₃)=NH) promoted by trifluoromethanesulfonic acid
Trifluoromethanesulfonic acid

Trifluoromethanesulfonic acid, also known as triflic acid or TfOH, is a sulfonic acid with the chemical formula CF3SO3H ....
. An example forming a p-methoxybenzyl (PMB) ether in total synthesis :

The benzyl group can be removed by hydrogenation

Hydrogenation

Hydrogenation is the chemical reaction that results from the addition of hydrogen . The process is usually employed to a redox or Saturation organic compounds....
. PMB ethers can be cleaved by magnesium bromide

Magnesium bromide

Magnesium bromide is a chemical compound of magnesium and bromine that is white and deliquescent. It is often used as a mild sedative. It was used as a laxative....
–dimethyl sulfide

Dimethyl sulfide

Dimethyl sulfide or methylthiomethane is an Organosulfur compounds compound with the formula 2S. Dimethyl sulfide is a water-insoluble flammable liquid that boils at 37?C and has a characteristic disagreeable odor....
, CAN or DDQ .

One study employs a benzyl pyridinium salt as a benzyl donor for alcohols:

The solvent is trifluoromethylbenzene and magnesium oxide

Magnesium oxide

Magnesium oxide, or magnesia, is a white solid mineral that occurs naturally as periclase and is a source of magnesium . It has an empirical formula of ....
is an acid scavenger

Scavenger (chemistry)

A scavenger in chemistry is a chemical substance added to a mixture in order to remove or inactivate impurities or unwanted reaction products. Their use is wide-ranged:...
. The reaction type for this conversion is believed to be S_N1 based on the detection of trace amounts of Friedel-Crafts reaction

Friedel-Crafts reaction

The Friedel-Crafts reactions are a set of organic reaction developed by Charles Friedel and James Crafts in 1877. There are two main types of Friedel-Crafts reactions: alkylation reactions and acylation reactions....
side-products with toluene

Toluene

Toluene, also known as methylbenzene or phenylmethane, is a clear, Water -insoluble liquid with the typical smell of paint thinners, redolent of the sweet smell of the related compound benzene....
as a solvent.