Question

Alkyl Shifts: 1. Construct a reaction diagram including 2,3-dimethylbutan-2,3-diol and H2SO, as the reactants. Include all lone pairs of electrons. 2. Identify the nucleophile and the electrophile in the drawing above. 3. Draw a double headed arrow beginning at the nucleophilic lone pair of electrons on one of the oxygen atoms of 2,3-dimethylbutan-2,3-diol and ending on the electrophilic hydrogen of H2SO4. Make sure to push the electrons in the bond between the H and HSO. onto the HSO4 so that the octet rule (actually the duet rule for H) is obeyed. 4. There should now be a positively charged oxygen atom on 2,3-dimethylbutan-2,3-diol. Try to draw the intermediate with the correct bond angles and shapes. 5. The positively charged oxygen makes for a great leaving group. Draw a double headed arrow beginning at the bond between the cand o atoms and ending on the oxygen atom. Notice that this breaks the sigma bond between C and O and water acts as a leaving group. This leaves behind a tertiary carbocation. Draw the newly formed carbocation. Try to draw this with the correct bond angles and shapes. 6. The carbocation is adjacent to another tertiary carbon with an oxygen atom attached to it. At this position there are also two methyl groups attached. One of these methyl groups can shift to the adjacent carbocation, along with the electrons in the bond. Draw a double headed arrow beginning at the electrons between the C of one of the methyl groups and ending at the carbocation. This now places the carbocation on the tertiary position, which also has resonance stabilization. This is the driving force for the shift 7. Draw the intermediate after the shift occurs and show the two resonance structures

Answer 1