Aldol Reaction : Assignment

Added on - 29 Apr 2020

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ABSTRACTThe goal of this lab experiment is to demonstrate how the reaction conditions influence theoutcome of an aldol reaction for the cyclohexanone with 1-naphthalene carboxaldehyde. Theaddition of solvents in the reaction scheme demonstrated the kinetic and thermodynamic controlof the reaction using the highlighted substrates. The technique used in the solvent extraction isthe separation funnel, TLC plate analysis, and the IR spectroscopy.REACTION SCHEMEIn the first step the base removes a proton from the alpha carbon to form a resonance-stabilizedenolate. The nucleophilic enolate attacks the electrophilic carbonyl carbon of another moleculeof aldehyde. As a result, a new carbon to carbon bond is formed. It joins the alpha carbon of onealdehyde to the carbonyl carbon of another aldehyde. The protonation of the alkoxide forms thebeta-hydroxy aldehyde[ CITATION Vog96 \l 1033 ].Carbon-carbon bond formation is one of thecornerstones of organic synthesis. One of the key reactions used, the aldol condensation, featuresthe reaction of two carbonyl compounds to form a new β-hydroxy carbonyl compound. Thisreaction can be performed under acid- or base-catalyzed conditions, and usually results in theformation of an α, β-unsaturated carbonyl compound. The general base-catalyzed reaction isshown in Scheme 1. One of the reacting species must contain a protonated α-carbon adjacent tothe carbonyl center. The proton attached to this carbon is acidic enough to be abstracted by baseto form an enolate species. Upon reaction with a second carbonyl compound, the β-hydroxycarbonyl compound is formed, which can undergo E1cB elimination of water to form an E-alkene.(i)0.09ml of cyclohexanone was added to the flask and left for about 30 minutes.(ii)0.12 naphthalene was added and left for about 2 minutes in the flask(iii)2 milliliters of NH4Cl was added and a separation funnel was set up as well as TIC(iv)The concentration obtained from the above was used to perform NMR. The productwas purified by the use of column chromatography and the samples submitted forNMR analysis. Determine the yield of the reaction, the identity of the product and theselectivity of the reaction.The first step obtains the enolate ion as,
The enolate in its stabilized resonance form is exposed to the nucleophilic addition such thata new C-C bond is formed,Such that J=8-10Hz to J=2-4 HzThe rotation is of 1800RESULTS AND DISCUSSIONThe aldol reaction of cyclohexanone with 1-naphthalene carboxaldehyde[ CITATION Sie \l 1033 ]A solution of Lithium diisopropylamide (LDA) is prepared by adding a solution of BuLi inhexanes in equivalent to 1 titer dropwise using a syringe to a stirred solution of freshly distilleddiisopropylamine in THF at 00C under an inert atmosphere.Componentw.mDensityEqMmolAmount (ml)Lidisopropylamide101.190.7221.110.14BuLi (0,58)64.060.6810.910.59Cyclohexanone98.140.94710.910.09C-heptalene carboxaldehyde156.181.1510.910.123M1= 66.9365gM2= 67.2722gThe total mass M=M2– M1, M= 0.3357gWhen the same solution was passed through a burette and the results were placed in test tubes of8 ml each,
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