IMG_NEW_0020 - a) b) \P1, RL 1' t r,, ;:ffi*r'1,...

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CHEM 28I Tutorial Problem Set No. 4 l. In class it was mentioned that E and Z isomers of alkenes have a barrier to interconversion of approximately 63 kcal/mol and, consequently, can be considered configurationally stable. However, in biological systems the isomerizatton (or EIZ interconversion) of alkenes may occur readily and plays an important role in many biological processes. Can you briefly describe the Z to E interconversion of Z-retinal and what role this plays in our ability to see? 2. Please name the following molecules and draw them in their most stable (chair) conformations. Highlight steric interactions (if any) in this conformation. This should be useful practice for you as this type of question caused the most difficulties on the
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Unformatted text preview: a) b) \P1, RL 1' t r,, ;:ffi*r'1, t-W'!1'T'-- I - hOfu*l- t-( t'|t'-ol4UL " vgl 4lr)- )'+, +-ttn,eff, ( )i'n, 07& k xo"Yrz ,'V c) (rR, rt,),;,,1,,,!*,, t\D->-Nql"1keff A)W)-4,+-oL"'rt4[ -'-?ttn dlVop\yfu b) @ (ts, +E r 6 ! -!,r1 Fd%! _ tl-_octu _>-o ( 3. Please name the-following molecules. arrange the following molecules in order oT stability (most stable to 4. Please stable). least _! . 3 >z>l z:-,-l'@ G o g 5. Please name the first two of following molecules and draw all possible resonance contributors for each. Circle the resonance structure that you feel would be the least stable. Show all relevant arrows used to convert between resonance structures. b) c) | o) e) @.'-\ )=-o.\d +,, ) H 5) 11A4fon- z-oyv...
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This note was uploaded on 12/27/2011 for the course CHEM 282 taught by Professor Nabylmerbouh during the Fall '10 term at Simon Fraser.

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