Question

My question:

1. Why does the isopropyl-pph3Br is attached to the aldehyde? why not in ketone?

2. Why does the pph3-CH2CHO is attached to the ketone? why not in aldehyde?

Kindly answer my question and explain the reaction happened there.

Thankyou so much

Synthesis of halomon from 2-butene No. Date od onolyes 0 NOW 740 но pph, Br oxidation of Neldim I chloro chromate reduction pph₂ CH, CHO > ephgår -OH Cusog dehydration Halomon

Answer 1

why are We need to understand a things be fore comincing to conclusion o What is Witig Reaction of its Mechonism ② Reactivity of ketone v/s aldehyde. aldehydes more reachive Induchive (+1) effect from both the alkyl gesup. make the carbonyl carbon of belone less électrophillie. R" 10 What is Wittig Reaction : → Reaction of ketones and aldehyde with phos phonium glides to foom Olefin stos + P PPh Ji In aldehydes there is presence. of tI effect from only 1 side. : Aldehydic carbon are more electrophillie than keteric carbon Hence Aldehyde will react preferentially, in presence of a kelone. eph. 15pph). * In the next step, i.e. WR нік, w ish to potente - Ru CH-CHD. 0-W TI CH- & In the case of the above Synthesis halomon f ketone Aldehyde being neore reachive woh than kelone, undergoes aldehyde. Witing Reaction Chemo selechvely. Scanned with CamScanner As now there is no competion btwn. Naturally Kefone will react with Withing ald & kefone reagent