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CH 318L EXPERIMENT

Aim : To synthesize trans, trans-1, 4-diphenyl-1, 3-butadiene by using the WittigReaction method

Reagents :

Benzyltriphenyl phosphonium

chloride

dichloromethane

Ethanol trans-cinnamaldehyde

Sodiumsulphate(anhydrous)

Sodiumhydroxide

IUPACname

phenyl(phenylme

thyl)phosphoniu

m chloride

Dichloromethane

Ethanol trans -3-Phenyl-2- propenal

Sodiumsulphate

Sodiumhydroxide

Mol. Wt. .87g/mol 84.93g/mol

46.06844 g/mol

132.16g/mol 142.04g/mol

39.997g/mol

Density -- 1.33g/cm !

0.789g/cm !

1.05 g/cm ! at 25 C(lit.)

2.664g/cm !

2.13g/cm !

M.P 330 C -96.7 C -114 C " 9-" 4 C(lit.)

884 C 318 C

B.P -- 39.6 C 78.37 C

250-252 C(lit.)

1429 C 1,388 C

Apparatus : pipette, burette, conical flask, beaker, measuring cylinder, magneticstirrer, dropper, magnetic stirrer

Theory : The Wittig reaction is an organic chemistry synthesis technique that allowsthe creation of a new carbon-carbon bond. A nucleophilic addition reactionmechanism is adapted for the conversion of aldehydes and ketones into alkenes.

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Mechanism of Wittig reaction :

Step1: Ylide formation (Ylide is a neutral dipolar molecule with opposite charges onadjacent atoms and they function as carbon nucleophiles)

Step2:Betaine formation (Betaine is neutral dipolar molecule with opposite chargeson non-adjacent atoms)

Step3: Oxophosphetane formation (Oxophosphetane is a 4-membered ring withadjacent oxygen and phosphorous atoms)

Step4: Breakdown of oxophosphetane

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Hazards:

Serial No. Reagent Hazard Information

1 Benzyltriphenylphophoniumchloride

Toxic if swallowed

2 Trans- cinnamaldehyde Irritating to eyes, skin, respiratory system,may cause sensitization by skin contact

3 Sodium Hydroxide Corrosive, causes severe burns

4 Dichloromethane Irritating to eyes, skin, respiratory system,

5 Ethanol Highly flammable

6 Sodium Sulphate Irritant