College Chemistry (250-06)
Tonny, Chan Kar Yu
Group: B1, Student ID: 10297729
Tonny, Chan Kar Yu,
Date of Experiment:
Stereochemistry of Butenedioic acid
To study the interconversion of two geometric isomers, maleic acid
(cis isomer) to fumaric acid (trans isomers), the differences in physical properties
between this pair of cis-trans isomers and determine the stereochemistry of addition of
bromine to butenedioic acid.
Chemicals and Apparatus:
2 grams of maleic acid, 10 cm
of concentrated hydrochloric acid, 10 cm
, one 50 cm
beaker, one 100 cm
beaker, one 250 cm
beaker, one 10 cm
measuring cylinder, one piece of spatula, one piece of water glass, one glass rod, a
few pieces of filter paper, a set of Buchner funnel, a filter flask with side tube, three
glass capillary tubes, a set of melting point apparatus, one long hollow glass tubing,
one electronic balance, one heater and the oven
Stereochemistry is always encountered throughout organic chemistry. And
stereochemistry isomerism can be divided into two classes, geometrical isomerism
and optical isomerism. Although these categories are not mutually exclusive, it is not
uncommon to find compounds that exhibit only one or the other of the two types.
Most geometrical isomers result from cyclic systems or restricted rotation about
double bonds. The preparation of fumaric acid by isomerization of maleic acid and
addition of molecular bromine to fumaric acid was illustrated in the experiment.
Geometric isomers can be interconverted if the double bond is temporarily converted
to a single bond, about which rotation is relatively free. For example, an electrophile
adds to the double bond, rotation becomes possible. Loss of the electrophile then
regenerates the double bond. If rotation occurred in the intermediate, the result is the
The result of this kind of transformation is an equilibrium mixture of the cis and trans
isomers. Frequently, the trans isomer is more stable, so the equilibrium mixture would
contain more of the trans isomer. The greater the difference is in the stability of the
isomers, the greater the concentration of the trans isomer will be at equilibrium.
The stock solution of bromine water was prepared by dissolving 232.5 g of Br
and 187.5 g KBr in
water and diluting to about 750 ml.
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