Search results
Results from the WOW.Com Content Network
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 ...
In the original paper describing this reaction, methylmagnesium bromide is reacted with isophorone with and without 1 mole percent of added copper(I) chloride (see figure). [10] Without added salt the main products are alcohol B (42%) from nucleophilic addition to the carbonyl group and diene C (48%) as its dehydration reaction product.
Trimethylsilylacetylene is commercially available. It may also be prepared in a manner similar to other silyl compounds: deprotonation of acetylene with a Grignard reagent, followed by reaction with trimethylsilyl chloride. [4] Trimethylsilylacetylene is a precursor to 1,4-bis(trimethylsilyl)buta-1,3-diyne, a protected form of 1,3-butadiyne. [5]
In acidic conditions, alkyl substituents acting as electron withdrawing groups decrease the reaction rate. [10] As bulker silyl groups are more likely to be electron withdrawing, it is easier to differentiate between less and more bulky silyl groups. [10] Therefore, acidic deprotection occurs fastest for less sterically bulky alkyl silyl groups ...
The reaction is named for Pierre Bruylants (1855–1950), [2] who first reported it in 1924. [3] The reaction mechanism appears to involve ejection of the nitrile to form an iminium that is then attacked by the Grignard rather than a direct displacement such as an S N 2 reaction.
The length of the resulting polymer is dependent on the concentration of chain ending groups that are added to the reaction mixture. The rate of the reaction is determined by the transfer of reagents across the aqueous-organic phase boundary; therefore, the reaction is most efficient under turbulent conditions.
To increase the rate of reaction, trimethylsilyl triflate may also be used in the place of trimethylsilyl chloride as a more electrophilic substrate. [ 4 ] [ 5 ] When using an unsymmetrical enolizable carbonyl compound as a substrate, the choice of reaction conditions can help control whether the kinetic or thermodynamic silyl enol ether is ...
The major advantage of this method over addition of organometallic reagents to more typical acyl compounds is that it avoids the common problem of over-addition. For these latter reactions, two equivalents of the incoming group add to form an alcohol rather than a ketone or aldehyde. This occurs even if the equivalents of nucleophile are ...