Question

Discussion Questions: 1. a) Carefully draw a three-dimensional structure of each stereoisomer of stilbene dibromide. Do not include any identical structures. b) Identify the enantiomeric pair, and identify one pair of structures that are diastereomers. 2. Give careful stereo-drawings representing the complete mechanism for the reaction of cis-stilbene with bromine. Remember to show the two different modes of anti-attack that are possible, depending on whether you add the bromine from above to the left-hand or the right-hand carbon of the double bond. Identify the products as two different enantiomers or as two drawings of the same meso compound. 3. In a similar way, give careful stereo-drawings representing the complete mechanism for the reaction of trans-stilbene with bromine. Identify these products as two different enantiomers or as two drawings of the same (meso) compound. Identify the product of your reaction as a meso compound or a racemic mixture of enantiomers. Remember to explain what you base this identification on. 5. Give clear stereo drawing(s) of the product(s) obtained. Match this or these with the drawings in #1, and with the help of the mechanisms in #2 and 3 identify your starting stilbene as cis or trans. Clearly explain how the mechanisms allow you to make this identification.

Answer 1

- (stilbene) a stilbere Dibromide) и и — ВА ВА — и Б) п 1 т і т 098 €алд ioM05. I is_mo8 0-. I sI and I s I are diastereomers.

2_2 RE HIBE BI Enantiomers rts

Q-4. In d-2 we get racemic mixture as when there is anti- addition on cis we get racemic mixture. Indz. we get meso as when there is anti- addition on tsans, we get meso.