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-Intermediate A is likely to have a lower molecular weight than the starting mat

ID: 560625 • Letter: #

Question

-Intermediate A is likely to have a lower molecular weight than the starting material. This can be predicted from the higher melting point.

-Intermediate A is likely to be water soluble due to its new bonds to Br.

-Intermediate A is likely to be much heavier (molecular weight) than E-stilbene due to the addition of two Br atoms.

-Intermediate A is a very strong base due to the two bromine atoms in its structure.

*What is the role of potassium hydroxide?

-strong base to perform the elimination reaction

-heterogeneous catalyst

-homogeneous catalyst

-good leaving group

-Intermediate A is likely to have a lower molecular weight than the starting material. This can be predicted from the higher melting point.

-Intermediate A is likely to be water soluble due to its new bonds to Br.

-Intermediate A is likely to be much heavier (molecular weight) than E-stilbene due to the addition of two Br atoms.

-Intermediate A is a very strong base due to the two bromine atoms in its structure.

*What is the role of potassium hydroxide?

-strong base to perform the elimination reaction

-heterogeneous catalyst

-homogeneous catalyst

-good leaving group

pyridinium perbromide MW 320 g/mole H'Br3 Addition: CH3CO2H mp 236-237 °C E-stilbene MW - 180 g/mole mp 123-125 Elimination: triethylene glycol diphenylacetylene MW- 178 g/mole mp=61

Explanation / Answer

Since two bromine atoms are added to stilbene the molecular weight should increase hence the correct answer is:

"Intermediate A is likely to be much heavier (molecular weight) than E-stilbene due to the addition of two Br atoms."

*In the second reaction Elimination of Br takes place in the presence of KOH which is a strong base, Hence correct answer is

"strong base to perform the elimination reaction"