41 wittig salt
Esmeralda Curiel
Organic Chemistry
October 21, 2014
Experiment 41- 1,4-Diphenyl-1,3-Butadiene
INTRODUCTION
The study of the Wittig Reaction is important because it is often used to form alkenes from carbonyl compounds. The purpose of this experiment is to isolate the trans, trans-1,4-diphenyl-1,3-butadiene, which is formed by a Wittig reaction along with the cis, trans isomeric diene. The reaction is carried out in two steps. First the Wittig salt is obtained through a simple nucleophilic displacement of chloride ion by triphenylphosphine. When treated with base, the Wittig salt forms a ylide which is a carbanion that acts as a nucleophile and adds to the carbonyl group. In this experiment, cinnamaldehyde is used as the carbonyl compound and yields mainly the trans, trans-1,4-diphenyl-1,3-butadiene. Purification was done via crystallization. Characterization was analyzed through TLC, UV-vis spectroscopy, and melting point.
As detailed in Pavia's Organic Laboratory techniques the reaction is expected to proceed via the following mechanism
PROCEDURE
The experiment was conducted using the procedures detailed in pages 327-333 of
Pavia D., Lampman G. M., Kriz G. S., and Engel R. G. A Small Scale Approach to Organic Laboratory Techniques, Third Edition). There were no exemptions to the procedure and this experiment was performed in collaboration with Paula Mendoza.
RESULTS
Key quantities and properties for this experiment are summarized in Tables 1-5. Relevant chemical quantities and properties are presented in Table 1, table 2 contains the calculations for Theoretical Yield of Wittig salt. Table 3 contains the Actual Wittig Salt Percent yield. Summary of Characterization Results in Table 4. Table 5 contains the TLC plate results.
Table 1: Relevant chemical quantities and properties
Compound
Quantities
Properties
triphenylphosphine
2.2 g
Clear liquid
Benzyl chloride
1.44 mL
Clear liquid xylenes 8.0 mL
Clear liquid
Benzyltriphenylphosphonium chloride
Organic Chemistry
October 21, 2014
Experiment 41- 1,4-Diphenyl-1,3-Butadiene
INTRODUCTION
The study of the Wittig Reaction is important because it is often used to form alkenes from carbonyl compounds. The purpose of this experiment is to isolate the trans, trans-1,4-diphenyl-1,3-butadiene, which is formed by a Wittig reaction along with the cis, trans isomeric diene. The reaction is carried out in two steps. First the Wittig salt is obtained through a simple nucleophilic displacement of chloride ion by triphenylphosphine. When treated with base, the Wittig salt forms a ylide which is a carbanion that acts as a nucleophile and adds to the carbonyl group. In this experiment, cinnamaldehyde is used as the carbonyl compound and yields mainly the trans, trans-1,4-diphenyl-1,3-butadiene. Purification was done via crystallization. Characterization was analyzed through TLC, UV-vis spectroscopy, and melting point.
As detailed in Pavia's Organic Laboratory techniques the reaction is expected to proceed via the following mechanism
PROCEDURE
The experiment was conducted using the procedures detailed in pages 327-333 of
Pavia D., Lampman G. M., Kriz G. S., and Engel R. G. A Small Scale Approach to Organic Laboratory Techniques, Third Edition). There were no exemptions to the procedure and this experiment was performed in collaboration with Paula Mendoza.
RESULTS
Key quantities and properties for this experiment are summarized in Tables 1-5. Relevant chemical quantities and properties are presented in Table 1, table 2 contains the calculations for Theoretical Yield of Wittig salt. Table 3 contains the Actual Wittig Salt Percent yield. Summary of Characterization Results in Table 4. Table 5 contains the TLC plate results.
Table 1: Relevant chemical quantities and properties
Compound
Quantities
Properties
triphenylphosphine
2.2 g
Clear liquid
Benzyl chloride
1.44 mL
Clear liquid xylenes 8.0 mL
Clear liquid
Benzyltriphenylphosphonium chloride