Question

7. When isopentyl ethanoate reacts with DIBAH it produces an aldehyde; however, if the same ester reacts with LAH, it produces ethanol. Why is this? Please draw reactions/intermediates/steps to explain. (5)

7. When isopentyl ethanoate reacts with DIBAH it produces an aldehyde; however, if the same ester reacts with LAH, it produces ethanol. Why is this? Please draw reactions/intermediates/steps to explain. (5)

Answer 1

Li Alty 2; 4) Alth Alty if Com #1 1 A1 (A & Que to this - ve Change easity give up hy sride to the electrophilae enten consonit group and therety produce a carbones compound Ality one carbonid compound formed basin reading Coondinate with Ally to produce Ry & Alth for further it transfer to alcohol, Aliny LiAlty, 0 LH + All # (isopentyl ethans are ) 1 i o (N - Ahh رب ال H. t O Alla ho 7 он # ethanol A1 len DIBAL DIBAL a ventral Convolent compound, Di inobutyl aruminium bydride and it is reactive. It reacts when esten Canbonil group Coordinate with is and thereby formed i type intermediate reading hydrolysed to give the corresponding Mr aldehyde with hemi-autal which is cant OM н (hemiacetal type) I tho OH R. н ethanal hemiacetal

i farthert eleefron is andailable only 9. 8 - NA 40 D 2e NOL OG NO 6) H. # IGN- H II This how This lone pair ring to resoname aromatic NO NO to the Ni HN from ano. ring A matic NO2 ND Na Z: NO OA IZ: ol To wa "NHWA H C H L wa NO NO WA Gro N-NH H
9. The nitrogen atom of 2,4-DNP, which is farthest from the aromatic ring (here - NH2 group) will take part in the reaction as the lone pair is free for reaction. Since the nitrogen atom(-NH-) close to the aromatic ring take part in resonance , it will not be available for any electrophilic centre. That is why the farthest amine will take part in reaction .