The Prévost reaction is

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

in which an

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

is converted by

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

and the

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

benzoic acid Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, wh ...

to a vicinal

diol A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. The most common industrial diol is e ...

with

anti Anti may refer to: *Anti-, a prefix meaning "against" *Änti, or Antaeus, a half-giant in Greek and Berber mythology *A false reading of ''Nemty'', the name of the ferryman who carried Isis to Set's island in Egyptian mythology * Áńt’į, or ...

stereochemistry. The reaction was discovered by the French chemist Charles Prévost (1899–1983). Prevost Reaction Scheme

Reaction mechanism

The reaction between silver benzoate (1) and iodine is very fast and produces a very reactive iodinium benzoate intermediate (2). The reaction of the iodinium salt (2) with an

gives another short-lived iodinium salt (3). Nucleophilic substitution ( S_N2) by the benzoate salt gives the ester (4). Another silver ion causes the neighboring group substitution of the benzoate ester to give the oxonium salt (5). A second S_N2 substitution by the benzoate anion gives the desired diester (6). Prevost Reaction Mechanism

In the final step

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

of the

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

groups gives the anti-diol. This outcome is the opposite of that of the related

Woodward cis-hydroxylation The Woodward cis-hydroxylation (also known as the Woodward reaction) is the chemical reaction of alkenes with iodine and silver acetate in wet acetic acid to form cis-diols. Woodward, R. B., (conversion of olefin into cis-diol) The reaction is nam ...

which gives

syn addition In organic chemistry, syn- and anti-addition are different ways in which substituent molecules can be added to an alkene or alkyne. The concepts of syn and anti addition are used to characterize the different reactions of organic chemistry by ref ...

Reaction mechanism

References

See also