1. (a) Write structural formulas for at least 14 by vaj64091

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									1.
(a) Write structural formulas for at least 14 stable compounds that
have the formula C4H8O.
(b) The IR spectrum of the unknown compound shows a strong peak
near 1730 cm-1. Which structures now remain as possible formulas
for the compound?
(c) The mass spectrum shows the peaks at m/z 44 (the base peak)
and m/z 29. Propose a structure for the compound and write
fragmentation equations showing how these peaks arise.
(a)
ethers

                                                                          O    O
       O                                        O            O
                  O                O                                               O


                                                         O            O
                 O                     O
                                                                                        

alcohols


                                       OH                        HO                OH
           OH                                                                 OH
                      OH                            OH


                      OH                                                      OH
                                                                                        

Aldehydes
and
ketones

       O                   O                O
            H                  H
                                                

(b)

       O                   O                O
            H                  H
                                                

(c)

       O

            H

                O       Ionization                    O         Fragmention
                                                                                                   O
                    H                                     H                           +
                                                                                                   CH
                                                                                                   29


                O        Ionization           H               Rearrangement                        OH
                                                  O
                                                                                      +
                    H                                                                                   H
                                                      H
                                                                                                   44       






2. Explain the following observations
(a) The molecular ion peak of a primary and secondary alcohol is
very small; with a tertiary alcohol it is usually undetectable.
(b) Primary alcohols show a prominent peak at m/z 31
(c) Secondary alcohols usually give prominent peaks at m/z 45, 59,
73 and so on.
(d) Tertiary alcohols have prominent peak at m/z 59, 73, 87 and so
on.

(a)
In
mass
spectroscopy,
the
loss
of
H2O
is
very
common
for
alcohols.


            H                         H

                                          H                                       +   H2O
                H
    R       O                 R       O                              R
                                                                                               

Tertiary
alcohol
has
more
β
hydrogens.
Therefore
it
is
more
likely
to
lose
water.


(b)


                                                                                              H
                H                                 H                                       O
R           O                         R       O                               R   +

                                                                                          31       

(c)

        R                                 R
                                                                                               H
                H                                 H                                       O
    R       O                         R       O                               R   +
                                                                                      R
                                                                                              45 when R = methyl
                                                                                              59 when R = ethyl
                                                                                              73 when R = propyl 

(c)


R''
       R                 R'' R                            +O H
               H                       H
R'         O             R'        O            R'
                                                      R      R''
                                                            59 when R, R'' = methyl
                                                            73 when R and R'' are a combination
                                                            ethyl and methyl                      







3. Two isomers having molecular formula C4H6O are both
symmetrical in structure. In their IR spectra, neither isomer when in
dilute solution in CCl4 has absorption in the 3600 cm-1 region. Isomer
A has absorption bands at approximately 3080, 1620 and 700 cm-1.
Isomer B has bands in the 2900 cm-1 region and at 1780 cm-1.
Propose a structure for A and possible structures for B.


                                   O
           O
           A

                              B        

4. Write structural formulas for each of the following:
(a) Three primary alcohols with the formula C4H8O.
(b) A secondary alcohol with the formula C3H6O.
(c) A tertiary alcohol with the formula C4H8O.
(d) Three ketones with the formula C5H10O.
(e) A tertiary amine with formula C3H7N.
(a)




                              OH
                                                     HO
                    OH                     OH
                               OH
                                                                   

(b)


           OH
                

(c)

            OH
                 

(d)

    O                                 O                   O

                                                                

(e)


        N
            



5. Propose a structure for the compound that has a molecular formula
C11H14O2. It has a tert-butyl group in the structure. Also show the
dimer via hydrogen bonding (Show the hydrogen bonding between 2
molecules.)
    O       OH
                                                  H
                                              O       O
                               t-Bu                           t-Bu
                                              O       O
                                                  H
        t-Bu                                                         

Extra problem
1



(a)
Br

(b)
4


                      Br

(c)
                       



                       or
(d)
                                      




                     Br79


                                  



2

EDACB


								
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