Synthesis of Dibenzalacetone
Purpose: To synthesize synthesize dibenzalacetone via an Aldol condensation reaction (See Handout for mechanism) Reaction !uation O
CH O
# %
"a#H
$ H3C
CH3
H C
H C
C
H C
H C
$
&aterials: Apparatus 'acuum ilter &eltin point thermometer •
H%#
•
*hemicals +enzaldehyde Acetone *,H-# *.H-#
Sodium thanol Hydro/ide *%H-# "a#H
Dibenzalacetone0 Dibenzylideneacetone *1,H12#
&olar &ass (0mol) +P (8*) &P(8*) Density (0ml) Solubility
13-41%
56436
.7477,1
2-43,
%.24%7%
1,641 5,41% 14322
5, 7. 34,71
19.66 .16 %41.
,64., 112 34,67
1.3 11% 141
;n ammonia
;n
Polar solvents
14.57
Polar solvents 14.5,
14.-1
Soluble in nonpolar solvents 14-27
=i>ipedia
=i>ipedia
=i>ipedia
*hemnet4com
Refractive 14525 ;nde/ (n D) Reference =i>ipedia
Pre ?aboratory @uestions: 1. Write a mechanism for the formation of benzalacetone from acetone and benzaldehyde.
2. Why did you use specific quantities of reagents that are called for in the synthesis of dibenzylacetone? #H is >no
&. Identify each of the attached spectra as benzaldehyde, acetone or dibenzalacetone.
Procedure
#bservations
Procedure: 14 =eih out 34%-5 of benzaldehyde and a theoretical !uantity of acetone4 *alculate the theoretical !uantity of acetone before you arrive for labB %4 Add the correct !uantities of these reaents toether4 (Cse the Rainin pipet to dispense the correct amount of acetone in microliters4) .4 Dissolve 34%5 of "a#H in %45 m? of up and crystallize4 134 *ollect the product by4 114 =ash the crystals the meltin point of the recrystallized product (113 o to 111o *)4
Acetone is very volatile so reaction must be capped Theoretical !uantity of acetone is 437%ml 'olume of benzaldehyde is 34%52ml =hen
Dibenzalacetone Data Table
m +enzaldehyde:EEEEEEEE34%-5EEEEEEE mol +enzaldehyde:EEEEEE433%5EEEEEE
&oles AcetoneEE4331.-EEEE
m Acetone:EEEE43,%,,EEEEEEE
µ? Acetone:EEEEEEEEEEEEEE
Theoretical Field (moles)EEEEE4331.-EEEEEE
Theoretical Field (rams):EEE4.16-EEEEE
Actual yield of recrystallized product:EE4%.12G4.16-133 I ,%4-EEEEEEEEE
Percent Field:EEEEE,%4-EEEEEEEEEE &eltin point of recrystallized product:EEEEEE1114,EEEEEEEEEEEE Conclusion
=e
Dibenzalacetone
Acetone
See chemical shift assinments in the Table belo<4
Dibenzalacetone