2-Methylundecanal is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

that is found naturally in

kumquat Kumquats (; zh, 金桔), or cumquats in Australian English, are a group of small fruit-bearing trees in the flowering plant family Rutaceae. Their taxonomy is disputed. They were previously classified as forming the now-historical genus ''For ...

peel oil. This compound smells herbaceous,

orange Orange most often refers to: *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Orange (colour), from the color of an orange, occurs between red and yellow in the visible spectrum * ...

, and

ambergris Ambergris ( or , la, ambra grisea, fro, ambre gris), ''ambergrease'', or grey amber is a solid, waxy, flammable substance of a dull grey or blackish colour produced in the digestive system of sperm whales. Freshly produced ambergris has a mari ...

-like.Molecule of the Month: Chanel No 5 and 2-methylundecanal
/ref> At high dilution it has a flavor similar to honey and nuts. It is a colorless or pale yellow liquid that is soluble in organic

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s such as

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

and

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

. It is used as a fragrance component in soaps, detergents, and perfumes.

Preparation

The first synthesis of 2-methylundecanal was recorded by Georges Darzens in 1904 from methyl nonyl ketone and

ethyl chloroacetate Ethyl chloroacetate is a chemical compound used primarily in the chemical industry. It is used as a solvent for organic synthesis and as an intermediate in the production of pesticides (such as sodium fluoroacetate Sodium fluoroacetate is an or ...

. This method of synthesis can be used to produce a variety of

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

s and became known as the

Darzens reaction The Darzens reaction (also known as the Darzens condensation or glycidic ester condensation) is the chemical reaction of a ketone or aldehyde with an α- haloester in the presence of a base to form an α,β-epoxy ester, also called a "glycidic es ...

and is still used today. 2-Methylundecanal is synthesized in industry by two main routes. The first route, like Darzens, involves converting methyl nonyl ketone to its glycidate by allowing it to react with alkyl chloroacetate. The glycidate then undergoes

saponification Saponification is a process of converting esters into soaps and alcohols by the action of aqueous alkali (for example, aqueous sodium hydroxide solutions). Soaps are salts of fatty acids, which in turn are carboxylic acids with long carbon chains. ...

followed by decarboxylation. :CH₃(CH₂)₈C(O)CH₃ + ClCH₂CO₂CH₃ → CH₃(CH₂)₈CH(CH₃)OCH(CO₂R) + HCl :CH₃(CH₂)₈CCH₃OCCO₂CH₃ + H₂O → CH₃(CH₂)₈CH(CH₃)CHO + CO₂ + ROH The second method for the synthesis of 2-methylundecanal begins with the conversion of undecanal to 2-methyleneundecanal by allowing it to react with

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...

in the presence of base. The 2-methyleneundecanal is then

hydrogenated Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic ...

to give 2-methylundecanal. The required undecanal is generated from 1-decene by

hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon d ...

. The resulting solution is over 50% 2-methyleneundecanal. The

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betwee ...

of this compound is hydrogenated and the resulting 2-methylundecanal is separated from the by-products using fractional distillation. :CH₃(CH₂)₇CH₂=CH₂ + H₂ + CO → CH₃(CH₂)₁₀CHO :CH₃(CH₂)₁₀CHO + HCHO → CH₃(CH₂)₈C(CH₂)CHO + H₂O :CH₃(CH₂)₈C(CH₂)CHO + H₂ → CH₃(CH₂)₈CH(CH₃)CHO

Chirality

2-Methylundecanal contains one

asymmetric carbon An asymmetric carbon atom (chiral carbon) is a carbon atom that is attached to four different types of atoms or groups of atoms. Le Bel-van't Hoff rule states that the number of stereoisomers of an organic compound is 2n, where n represents the num ...

atom.

2-Methylundecanal Structural Formulae of both Enantiomers

The enantiomers can be synthesized with high enantiomeric purity using the SAMP/RAMP hydrazone method. This process involves starting with simple achiral aldehydes and converting them to their SAMP hydrazones then obtaining the corresponding chiral hydrazones using RAMP as a chiral auxiliary. The chiral hydrazones are then metalated with

lithium diisopropylamide Lithium diisopropylamide (commonly abbreviated LDA) is a chemical compound with the molecular formula . It is used as a strong base and has been widely utilized due to its good solubility in non-polar organic solvents and non-nucleophilic nature ...

(LDA) and

alkylated Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting al ...

with a slight excess of dimethyl sulfate. Testing of the enantiomers by a professional perfumer indicated only a slight difference in odor quality and intensity.

Applications

2-Methylundecanal is used widely as a

fragrance An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently ...

element in

soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...

s and detergents as well as in the perfume industry to give conifer notes, fir in particular, but is also used in fantasy compositions. This aldehyde was one of the first synthetics to be used in a prestigious perfume, namely

Chanel No. 5 Chanel No. 5 was the first perfume launched by French couturier Gabrielle "Coco" Chanel in 1921. The scent formula for the fragrance was compounded by French-Russian chemist and perfumer Ernest Beaux. The design of its bottle has been an impo ...

References

External links

Molecule of the Month: Chanel No 5 and 2-methylundecanal

Preparation

Chirality

Applications

References

External links

Further reading