Search results
Results from the WOW.Com Content Network
Grignard reagents or Grignard compounds are chemical compounds with the general formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride Cl−Mg−CH 3 and phenylmagnesium bromide (C 6 H 5)−Mg−Br. They are a subclass of the organomagnesium compounds.
A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
Carboxylic acids react with Grignard reagents and organolithiums to form ketones. The first equivalent of nucleophile acts as a base and deprotonates the acid. A second equivalent will attack the carbonyl group to create a geminal alkoxide dianion, which is protonated upon workup to give the hydrate of a ketone.
Example of syntheses from esters and lactones. A variety of peptide coupling reagents can also be used to prepare Weinreb–Nahm amides from carboxylic acids. Various carbodiimide-, hydroxybenzotriazole-, and triphenylphosphine-based couplings have been reported specifically for this purpose. [6] [7] Example of Syntheses from Carboxyllic Acids
The Kulinkovich reaction describes the organic synthesis of substituted cyclopropanols through reaction of esters with dialkyldialkoxytitanium reagents, which are generated in situ from Grignard reagents containing a hydrogen in beta-position and titanium(IV) alkoxides such as titanium isopropoxide. [1]
Acyl chlorides are used to prepare acid anhydrides, amides and esters, by reacting acid chlorides with: a salt of a carboxylic acid, an amine, or an alcohol, respectively. Acid halides are the most reactive acyl derivatives, and can easily be converted into any of the others. Acid halides will react with carboxylic acids to form anhydrides.
Specifically carbonation (i.e. carboxylation) of Grignard reagents and organolithium compounds is a classic way to convert organic halides into carboxylic acids. [ 4 ] Sodium salicylate , precursor to aspirin , is commercially prepared by treating sodium phenolate (the sodium salt of phenol ) with carbon dioxide at high pressure (100 atm) and ...
Nitronates are also key intermediates in the Nef reaction: when exposed to acids or oxidants, a nitronate hydrolyzes to a carbonyl and azanone. [26] Grignard reagents combine with nitro compounds to give a nitrone; but a Grignard reagent with an α hydrogen will then add again to the nitrone to give a hydroxylamine salt. [27]