In: Science

Submitted By wilberm21
Words 710
Pages 3
The purpose of this experiment was to synthesize tetraphenylcyclopentadienone by reacting dibenzyl ketone with benzil in the presence of a base. The reaction proceeded via an aldol condensation reaction with dehydration, and then the product crystals were isolated by vacuum filtrations using a Buchner funnel.
Experiment Scheme

Equation 1. Aldol condensation reaction between benzil and dibenzyl ketone in the presence of a base
To begin the experiment 1.5g of benzil, 12mL absolute ethanol and 1.5g of dibenzyl ketone were added to a 50-mL round bottom flask. A stir bar was added and the flask was attached to a condenser and heated in a water bath to 70◦C. The mixture was heated with sitting until the solids dissolved. Once solids were dissolved the temperature was raised to 80◦C with stirring. Using a Pasteur pipet, 2.25mL of ethanolic potassium hydroxide were added drop wise downward through the condenser into the flask. The mixture turned deep purple. After this, the temperature was raised to 85◦C and remained at that temperature with stirring for 15 minutes. After the heating period the flask was removed from the hot water bath and cooled to room temperature. Once at room temperature the flask was placed in ice-water bath for 5 minutes to complete crystallization of product. Using a Buchner funnel we collected the deep purple crystals. The crystals were washed with three 4-mL portions of cold 95% ethanol. The 95% ethanol was also used to rinse out the flask to retain as many crystals as possible. After allowing the crystals to dry some in the Buchner funnel the tetraphenylcyclopentadienone was placed in an oven for 15 minutes to dry. Once the drying time was complete we weighed our product and calculated the percent yield along with the melting point.

Table 1. Chemical table of…...

Similar Documents

Aldol Condensation

...An Aldol Condensation Reaction: The Synthesis of Tetraphenylcyclopentadienone—An Example of a Double-Crossed Aldol Addition Reactions of Carbonyl Groups The chemical reactivity of aldehydes and ketones is closely associated with the presence of the carbonyl group in their structures. For example, both aldehydes and ketones undergo addition reactions such as the addition of a Grignard reagent to the carbonyl group as shown in Figure 1. Figure 1. Addition reactions. The reactions in Figure 1 differ only because the pink H of an aldehyde is replaced by R′′ in the ketone. The addition reaction occurs at the carbonyl group. The carbonyl group is polarized so that the carbon atom bears a partial positive charge and the oxygen atom bears a partial negative charge. The R′ group of the Grignard reagent is negative relative to the positive Mg atom. Thus, the negative R′ group bonds to the positive carbon atom, and the negative oxygen and metallic magnesium form an ionic bond, yielding a salt in each reaction. The addition product is acidified in each case to make a covalent alcohol. The aldehyde produces a IIo alcohol; whereas, the ketone produces a IIIo alcohol owing to the R′′ group. The two equations for addition reactions in Figure 1 are summarized in Figure 2. A nucleophile (negative species) bonds to the carbonyl carbon (positive), breaking the π bond of the carbonyl group. Figure 2. Addition of a nucleophile to a carbonyl group. Figure 2 focuses our...

Words: 2021 - Pages: 9