Aldol In this preparative lab‚ an aldol (trans-p-anisalacetophenone) was produced from the reaction between p-anisaldehyde and acetophenone with the presence sodium hydroxide. The reaction also showed the importance of an enolate and the role it played in the mechanism. Sodium hydroxide acts as a catalyst in this experiment and is chosen because of its basic conditions and pH. The acetophenone carries an alpha hydrogen that has a pKa between 18 and 20. This alpha hydrogen is acidic because of its
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tetraphenylcyclopentadienone from benzaldehyde and to run reactions on carbonyl containing compounds. There was a total of three steps that led up to the synthesis of the final product‚ tetraphenylcyclopentadienone. The first step of the experiment was the condensation of benzaldehyde to yield benzoin. Thiamine catalyst along with water and ethanol were added to the benzaldehyde‚ then NaOH was added until the solution turned yellow. After recrystallization‚ the product was benzoin. Step two was the oxidation
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ketones takes place. Actually this reaction is a combination of two reactions. One is ’Michael Addition ’ and the other is ’Aldol Condensation ’. Robinson Annulation Mechanism In the first step‚ Micheal addition takes place to an α‚β-unsaturated ketone. Enolate is formed and tautomerization takes place for further reaction. Cyclization takes place. That is‚ aldol condensation reaction to form six-membered cyclic product. Further hydrolysis results in the formation of α‚β-unsaturated cyclic ketones
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Preparation and Identification of Dibenzylidene Acetone Purpose: Prepare dibenzylidene acetone by the famous Claisen-Schmidt condensation reaction. Learn the experimental skills of organic synthesis‚ separation‚ purification‚ structural characterization by instrumental analysis. Train the ability to solve the practical problems. Principle: Aromatic aldehydes can have aldol reaction with aldehydes or ketones which have α-hydrogen atoms‚ dehydrate to form high yield of α‚β-unsaturated aldehydes
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4.29.14 Aldol Condensation Introduction The purpose of this lab was to prepare dibenzalacetone (1‚5-diphenyl-1‚4-pentadiene-3-one). The preparation of dibenzalacetone is base catalyzed. It is a compound reaction that involves an aldol reaction and then dehydration. This overall reaction is known as the Clasien-Schmidt condensation. Aldol addition occurs when an aldehyde forms an aldol in equilibrium. Usually two molecules of aldehydes combine with a base two form the aldol‚ which is a compound
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ketone (1‚3-diphenyl-2-propanone) with benzil in the presence of base. The reaction then proceeded with an aldol condensation reaction.5 This product was obtained using extraction (reflux)‚ recrystallization and vacuum filtration to separate the product from the waste. Experiment Scheme: Figure 1: Experiment Reaction5 Figure 2: Step wise reaction mechanism including aldol condensation reaction5 Procedure: About 1.55-g of benzil‚ 1.51-g of dibenzylketone and 12-mL of ethanol were placed in
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Experiment2: Preparation of Dibenzalacetone Aim: Using the cabon-cabon bond making ability in carbonyl chemistry‚ Dibenzalacetone is synthesized from 2 equivalent of benzaldehyde and 1 equivalent of acetone in a base catalyzed reaction. Physical Data1: *detailed risk and safety phrases are attached. substance Hazards‚ risks and safety practices MW (g/mol) Amt. Used Mol. mp (K) bp (K) density(g/cm^3) acetone R11‚ R36‚ R67‚ S9‚ S25‚ S26 58.08 0.24 g 0.004 178.2 329.4 0.79 benzaldehyde R22
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carbonyl groups. One technique used was Doebner reaction and the other technique used was Claisen-Schmidt reaction. Therefore the aim of this experiment is to synthesize trans p-methoxycinnamic acid and to synthesize dibenzalacetone via an aldol condensation reaction between acetone and benzaldehyde. The products would be recrystallized using ethanol‚ then characterized using melting point analysis. Introduction: In this experiment we learnt on carbonyl compounds‚ enols and enolates. We also
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BOILING AND CONDENSATION BOILING • Phase change phenomenon where in transformation of liquid to vapour occurs at the saturation temperature of the fluid. It occurs at a solid/liquid interface due to convection heat transfer from the solid and usually occurs at surface temperatures higher than the saturation temperature of the fluid Agitation of fluid by vapor bubbles provides large convection coefficients Modified Newton’s law of cooling qs’’ h Ts Tsat Te • • • BOILING – CLASSIFICATON
Free Heat transfer Heat
remaining 2 mL of ethanol FIND SOLVENT: Test 95% ethanol and toluene Addition of a few drops hexane may be necessary to promote crystallization If not satisfactory test 9:1 v/v mixture of 95% ethanol/acetone Recrystallize Characterization of aldol product Perform this test on both unknown compounds Add 1 drop of the unknown compound to a test tube and add 1 mL of acetone Then Add 1 drop of the chromic acid-sulfuric test reagent directly into the solution. Shake the mixture A green bluish
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