Ishikawa's reagent is a fluorinating reagent used in organic chemistry. It is used to convert

alcohols In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...

into alkyl fluorides and

carboxylic acids In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

into

acyl fluoride An acyl halide (also known as an acid halide) is a chemical compound derived from an oxoacid by replacing a hydroxyl group () with a halide group (, where X is a halogen). In organic chemistry, the term typically refers to acyl halides of carbox ...

Aldehydes In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

and

ketones In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

do not react with it. The reagent consists of a mixture of ''N'',''N''-diethyl-(1,1,2,3,3,3-hexafluoropropyl)amine and ''N'',''N''-diethyl-(''E'')-pentafluoropropenylamine in varying proportions. The active species is the hexafluoropropylamine; any

enamine An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the r ...

is converted into this by the

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

byproduct as the reaction proceeds. Ishikawa's reagent is a popular alternative to the DAST reagent, since it is shelf-stable and easily prepared from inexpensive and innocuous reagents. It is an improvement on Yarovenko's reagent, the adduct of

chlorotrifluoroethylene Chlorotrifluoroethylene (CTFE) is a chlorofluorocarbon with chemical formula CFCl=CF2. It is commonly used as a refrigerant in cryogenic applications. CTFE has a carbon-carbon double bond and so can be polymerized to form polychlorotrifluoroethy ...

and

diethylamine Diethylamine is an organic compound with the formula . It is classified as a secondary amine. It is a flammable, volatile weakly alkaline liquid that is miscible with most solvents. It is a colorless liquid, but commercial samples often appear br ...

, which must be prepared in a sealed vessel and once prepared keeps only for a few days, even in the refrigerator. The reagent is mostly used to convert primary alcohols to alkyl fluorides under mild conditions with high yield. However, secondary and tertiary alcohols give a substantial amount of alkenes and ethers as side products.

Synthesis

The compound is prepared by adding

hexafluoropropene Hexafluoropropylene is the fluoroalkene with the formula CF3CF=CF2. It is the perfluorocarbon counterpart to the hydrocarbon propylene. It is mainly used to produce copolymers with tetrafluoroethylene. Hexafluoropropylene is used as a chemical i ...

to a solution of

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

at 0 °C and distilling the product ''in vacuo''. The amount of enamine in the product depends on temperature control during the reaction – the higher the temperature the more enamine.

References

* {{cite journal , doi = 10.1246/bcsj.52.3377 , title = F-Propene-Dialkylamine Reaction Products as Fluorinating Agents , journal = Bulletin of the Chemical Society of Japan , volume = 52 , issue = 11 , pages = 3377 , year = 1979 , last1 = Takaoka , first1 = Akio , last2 = Iwakiri , first2 = Hiroshi , last3 = Ishikawa , first3 = Nobuo , doi-access = free Organofluorides Reagents for organic chemistry Fluorinating agents Alkene derivatives