Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Knoevenagel reaction

25,838 views

Published on

Published in: Education
  • Hi there! I just wanted to share a list of sites that helped me a lot during my studies: .................................................................................................................................... www.EssayWrite.best - Write an essay .................................................................................................................................... www.LitReview.xyz - Summary of books .................................................................................................................................... www.Coursework.best - Online coursework .................................................................................................................................... www.Dissertations.me - proquest dissertations .................................................................................................................................... www.ReMovie.club - Movies reviews .................................................................................................................................... www.WebSlides.vip - Best powerpoint presentations .................................................................................................................................... www.WritePaper.info - Write a research paper .................................................................................................................................... www.EddyHelp.com - Homework help online .................................................................................................................................... www.MyResumeHelp.net - Professional resume writing service .................................................................................................................................. www.HelpWriting.net - Help with writing any papers ......................................................................................................................................... Save so as not to lose
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • I can definitely recommend a website that really helped me with my essay. I found out it was due the day before I had to submit it. Went into full-on panic mode. Worst experience of my senior year by far. It’s called HelpWriting.net. The quality of the writing is passable but the completion rate is super quick. You get to pick your own writer to do your stuff and that’s also a big bonus.
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Dating for everyone is here: ♥♥♥ http://bit.ly/39mQKz3 ♥♥♥
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Sex in your area is here: ❤❤❤ http://bit.ly/39mQKz3 ❤❤❤
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • nice attempt
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here

Knoevenagel reaction

  1. 1.  Knoevenagel condensation is nucleophilic addition of an active hydrogen compound to a carbonyl group followed by a dehydration reaction in which a molecule of water is eliminated (hence Condensation). The product is often an alpha, beta conjugated enone.  Knoevenagel reaction is a modification of Aldol condensation reaction.  The active hydrogen compound used should be of the form Z-CH2-Z or Z-CHR-Z where Z is an electron withdrawing group.
  2. 2.  Eg: Diethyl malonate, Malonic acid and ethyl acetoacetate H5C2OOC-CH2-COOC2H5 Diethyl malonate HOOC-CH2-COOH Malonic acid Z must be powerful enough to facilitate deprotonation to the enolate ion even with a mild base. Using a strong base in this reaction would induce self-condensation of the aldehyde or ketone.
  3. 3.  The carbonyl group is an aldehyde or a ketone.  Eg: Acetaldehyde (CH3CHO), Acetone (CH3CO CH3)  The catalyst is usually a weakly basic amine.  Eg: Pyridine (C5H 5N)
  4. 4. Knoevenagel condensation is nucleophilic addition of an active hydrogen compound to a carbonyl group followed by a dehydration reaction in which a molecule of water is eliminated (hence Condensation). The product is often an alpha, beta conjugated enone.
  5. 5. The condensation of carbon acid compounds with aldehydes to afford α,β-unsaturated compounds. The Doebner Modification, which is possible in the presence of carboxylic acid groups, includes a pyridine-induced decarboxylation
  6. 6.  Step:1: An enol intermediate is formed initially.
  7. 7.  Step:2: The enol formed reacts with aldehyde, and the resulting aldol undergoes based induced elimination.
  8. 8.  With malonic compounds the reaction product can lose a molecule of carbon dioxide in a subsequent step. The base is pyridine. For example, the reaction product of acrolein (allyl aldehyde) and malonic acid in pyridine is trans-2,4-Pentadienoic acid with one carboxylic acid group and not two. Acrolein Malonic acid trans-2,4-Pentadienoic acid
  9. 9.  The Knoevenagel condensation is a key step in the commercial production of the antimalarial drug lumefantrine.  Knoevenagal reaction is used in the synthesis of conjugated enones which serve as key intermediates in various reactions.  The Hantzsch pyridine synthesis, the Gewald reaction and the Feist–Benary furan synthesis all contain a Knoevenagel reaction step. The reaction also led to the discovery of CS gas.

×