Experiments 30.08.2019
 Experiments Article



With this experiment we all used two techniques for the reactions of enolate ions with carbonyl groups. A single technique used was Doebner response and the various other technique used was Claisen-Schmidt effect. Therefore the purpose of this experiment is to synthesize trans p-methoxycinnamic acid and to synthesize dibenzalacetone via an aldol moisture build-up or condensation reaction between acetone and benzaldehyde. The products would be recrystallized using ethanol, then characterized using burning point examination.


With this experiment all of us learnt about carbonyl chemical substances, enols and enolates. All of us also discovered two several techniques to test the reactions of enolate ions with carbonyl groupings which are mentioned below. My spouse and i. Carbonyl Compounds, Enols and Enolates.

Many of the most suitable reactions of carbonyl compounds have carbon hydrogen bonds next to the carbonyl group. This sort of reactions, which is often observed while the strength of very much synthetic organic chemistry, usually result in the replacement of the hydrogen by various other atom or group, as in the H-C-C=O -+ X-C-C=O. Transformation of the carbonyl compound to an enol at the right rate typically needs whether basic catalyst or an acidic catalyst and, of course , at least one hydrogen on the a carbon.

Even though these types of reactions cause numerous various products subjecting to the reagents and circumstances, they have a single feature shared- they continue by way of the en01 or the enolate anion from the parent carbonyl compound as shown below.

2. Knoevenagel Moisture build-up or condensation Reaction

The Knoevenagel condensation reaction is usually an organic effect named after Emil Knoevenagel. It is a reform from the Aldol condensation. A Knoevenagel condensation is a nucleophilic addition of an lively hydrogen compound to a carbonyl group followed by a dehydration reaction where a molecule of water can be eliminated (hence condensation). The product is often a great alpha, beta conjugated enone. An example is usually shown below.

From this reaction the aldehyde or possibly a ketone can be an carbonyl group. The catalyst is generally a weakly basic amine. The effective hydrogen component has the kind •Z-CH2-Z or perhaps Z-CHR-Z intended for diethyl malonate, Meldrum's acidity, ethyl acetoacetate or malonic acid. •Z-CHR1R2 for nitromethane.

where Unces is an electron removing functional group. Z has to be dominant to enable hydrogen etre to the enolate ion despite a mild base. With a solid base from this reaction will make self-condensation with the aldehyde or perhaps ketone. The Hantzsch pyridine synthesis, the Gewald reaction and the Feist-Benary furan activity all include a Knoevenagel reaction stage. The reaction as well steered to the finding of CS gas. III. Doebner Reaction

To sum up reaction, The Doebner transform of the Knoevenagel condensation. Acrolein and malonic acid react in pyridine to give trans-2, 4-pentadienoic chemical p with the loss in carbon dioxide. With malonic things the reaction product can miss a molecule of carbon dioxide in a after step. In the so-called Doebner modification the base is pyridine. For instance, the reaction product of acrolein and malonic acidity in pyridine is trans-2, 4-Pentadienoic acidity with one particular carboxylic acid group and never two.


There were two parts for this experiment. As i have said under the seeks, we tested the reactions using two techniques: a)We placed p-anisaldehyde (p-methoxybenzaldehyde), malonic acid and pyridine within a 100ml circular bottom flask, and match a reflux condenser. In the table under the amount of p-anisaldehyde, malonic acid and pyridine will be shown.

P-anisaldehyde3. 30ml

Malonic acid6. 505g


Desk 1

All of us then moved to the fume hood to put together and carry out the research. In the blow up hood, 5 drops of pyridine was added in the round underlying part flask and heated within an oil bathroom under reflux for 90 minutes. During this time period, bubbles of carbon dioxide advanced were seen. After 90 minutes under reflux, the...

References: 1 . ^ Jones, G. Org. Respond. 1967, 12-15.

2 . ^ Emil Knoevenagel (1898). " Condensation von Malonsäure mit Aromatiachen Aldehyden durch Ammoniak und Amine". Berichte der deutschen chemischen Gesellschaft 23 (3): 2596–2619. doi: 10. 1002/cber. 18980310308.

3. ^ March, Jerry (1985), Advanced Organic Hormone balance: Reactions, Mechanisms, and Structure (3rd education. ), Nyc: Wiley, ISBN 0-471-85472-7

5. ^ To. Doebner (1902). " Ueber die dieser Sorbinsäure homologen, ungesättigten Säuren mit die Doppelbindungen". Berichte der deutschen chemischen Gesellschaft 35: 1136–1136. doi: 10. 1002/cber. 190203501187.

5. ^ Peter M. Jessup, C. Bruce Small, Jan Roos, and Lewis E. Overman (1988), " 1-N-Acylamino-1, 3-dienes from 2, 4-pentadienoic acids by the curtius rearrangement: benzyl trans-1, 3-butadiene-1-carbamate", Org. Synth.; Coll. Volume. 6: ninety five

6. ^ 1, 3-Diethyl-5-(2-methoxybenzylidene)-2-thioxodihydropyrimidine-4, 6(1H, 5H)-dione Abdullah Mohamed Asiria, Khaled Ahmed Alamrya Abraham F. Jalboutb, Suhong Zhang Molbank 2004, M359 [1] newsletter.

7. ^ An Improved Production Process to get the Antimalaria Drug Coartem. Part 2 Ulrich Beutler, Peter C. Fuenfschilling, and Andreas Steinkemper Org. Procedure Res. Dev.; 2007; 11(3) pp 341 - 345; (Article) doi: 10. 1021/op060244p

8. ^ Mild and ecofriendly with a friend synthesis of 1, 2, 4-triazolo[4, 3-a]pyrimidines in aqueous moderate Arkivoc 3 years ago (06-2251BP) Anshu Dandia, Pritima Sarawgi, Kapil Arya, and Sarita Khaturia Link

on the lookout for. Chemistry Research laboratory Experiments CHEM 224 SYNT 720 pgs. 85 - 95 Wigal/Manion/LeFevre/Wade, Jr. /Rapp/Lee/Wikholm

12. Weast, Robert C., impotence. CRC Guide of Biochemistry and Physics. 70th ed. Boca Raton, FL: CRC Press, Inc., 1990.

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