What is active methylene compounds give example?
Compounds possessing a methylene bridge located between two strong electron withdrawing groups (such as nitro, carbonyl or nitrile groups) are sometimes called active methylene compounds. Treatment of these with strong bases can form enolates or carbanions, which are often used in organic synthesis.
In which reaction is active methylene group involved?
Knoengel condensation is the reaction of an aldehydes or ketone with an active methylene group containing compound in presence of weak base.
What is an example of compound containing reactive methylene group?
Malonic ester contains an active methylene group and two hydrogen atoms of active methylene group are easily replaced by alkyl and acyl groups in the presence of strong base.
What is active methylene?
An active methylene compound is a compound that has the following general structural formula. eg: The conjugate base of an active methylene compound is highly resonance stabilized.
What are active methylene compound Why is the methylene group active?
Active methylene compounds have a -CH2- attached to electron withdrawing groups like carbonyl, cyanide etc., Because of the attraction of electrons by the groups present on both sides the hydrogens in CH2 become labile and can be easily removed to produce a carbanion which can react further.
Which of the following is not an active methylene compound?
Pentanoic acid does not belong to the class of active methylene compounds. So option (d) is correct. Active methylene compounds possess a methylene group whose hydrogens are acidic.
Why is ethyl acetoacetate called active methylene compound?
This is so because the -CH2- group in them is acidic and reactive. Ethyl acetoacetate (Acetoacetic ester) and Diethyl malonate (Malonic ester) belong to this class.
What is nature of enolate formed from active methylene?
Due to the acidic nature of methylene hydrogen, it form salt with sodium ethoxide (base). This salt act as nucleophile which can take part in SN reaction.
What is the effect of electron withdrawing group on reactivity of active methylene group?
The effect of other substituent groups on the reactivity of the methyl substituents is also generally predictable; for example, electron-withdrawing groups further increase the reactivity, i. e., facilitate proton removal from methyl groups ortho and para to them.
Which is not a example of active methylene compound?
Pentanoic acid does not belong to the class of active methylene compounds.