{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Solutions_Manual_for_Organic_Chemistry_6th_Ed 323

Solutions_Manual_for_Organic_Chemistry_6th_Ed 323 - 1 4-47...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 4-47 The fonnula CgHgO has five elements of unsaturation (enough (4) for a benzene ring). The IR i s usefu l for what is does n ot s how . There i s neither OH nor C=O, so the oxygen must be an ether functional group. The NMR s hows a 5H signal at 8 7 .2, a monosubstituted benzene. No peaks in the 8 4. 5 -6.0 range indicate the absence of an alkene, so the remaining element of un saturation must be a ring. The three protons are non-equi valent, with complex splitting. These pieces can be assembled in only one manner consistent with the data. <> + 2C + 0 ether + 3 H + r ing (Note that the CH2 hydrogen s are not equi valent (one is cis and one is t rans t o the phenyl) and therefore have distinct chemical shifts . ) 1 4-48 The key concept is that reagents always go to the less hindered side o f a molecule first. I n this c ase, t he " underneath" side is less hindered; the " top" side has a CH3 hovering over the double bond and approach from the top w i l l be much more difficult, and therefore slower, than approach from underneath . � H H H M CPB A MCPBA approaches from the bottom; the epoxide is fanned from MCPB A w i thout the participation of any other reagent. The epoxide fonns on the less hindered side. B less hindered side J B r2 I o n the less hindered side fonnation of the bromohydrin begins with fonnation of the bromonium ion 2 ,6-lutidine w ater m ust attack from the side opposite the bromonium ion , from the TOP Br o c E poxides B and C are di astereomers ; they will have different chemical and physical properties. Nucle� philes can react with C m uch faster than with B for precisely the same reason that explai ned thei r fonnatlOn: approach from underneath i s less hindered and is faster than approach from t h e top. 3 16 ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online