Methyl Salicylate

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					Experiment 9: Preparation of Methyl Salicyclate
O
                            O

     OH
                    H2SO4
          + CH3OH                OCH3   + H2O

OH
                            OH
Wintergreen (methyl salicylate) Gaultheria procumbens This tiny, North American
plant of the heath family grows in pine forests and on humid ground with sphagnum.
The Indians knew its effects, which is due to methyl salicylate. Like salicylic acid,
it is analgesic and antipyretic.


                                                    O         OCH3


                                             HO




                                                                      *bottle
Experimental setup: total reflux
                                                                                              OCH3
                              Vacuum Distillation                                  O


                                                                              HO

                             Vapor Pressure vs Temperature of Water                              BP 222 °C at 100 kPa
                       250


                       200
                                                                              At what temperature will it boil
                                                                              at 10 kPa?
Vapor Pressure (kPa)




                       150


                       100                                                         P/kPa             T/ C

                        50
                                                                                       100             22
                                                                                        50            210
                         0
                                                                                        25            200
                                                                                       12.5           190
                               0    20   40    60      80   100   120   140
                                          Temperature, °C                               6.3           180
                             Rule of thumb: BP decreases                                3.1           170
                             by 10 °C each time the atm                                 1.6           160
                             pressure decreases by ½.                                   0.8           150
                                                                                        0.4           140
How do I go about figuring out what my unknown is?


1. From your solubility measurements, you should be able to
   classify your unknowns according to the solubility classes
   discussed.
2. Look up some reference IR spectra in your manual that have
   the possible functional groups present in your unknown.
3. Look up some possible classification tests you can run to
   confirm their presence.
4. Complete and hand in your preliminary report if you haven’t
   done so.
5. Select a possible derivative based on the properties of the
   derivative. For example, choose a derivative that will allow
   you to distinguish between other possible compounds with
   melting points (±5 C) or boiling points (±10 C) within the
   value of your unknown
Classification Tests
Classification test should only be run to confirm your suspicions
regarding the presence of a functional group suggested by your solubility
tests or IR. Always run a blank and a known at the same time you run
your unknown so that you know what a positive test looks like and that
you performed the classification test properly.


Derivatives


A derivative should be chosen whose melting temperature will allow you
to differentiate between possible compounds. If you have a carboxylic
acid or an amine, a titration can be substituted for a derivative providing
that the molecular weights of other possible compounds in your
possibility list can be excluded on the basis of your titration results.
                   What information can we deduce from this spectrum?


                  100


                  80
% Transmittance




                  60


                  40


                  20


                   0                                      1718 cm-1
                    4000       3500   3000   2500      2000      1500   1000   500
                                             Wavenumbers, cm-1
                        neat liquid
          What information can we deduce from this spectrum?


                  100


                   80
% Transmittance




                   60


                   40


                   20


                    0
                     4000    3500   3000   2500    2000      1500   1000   500
                                           Wavenumber cm-1


                  KBr disk
                  100


                  80
% Transmittance




                  60
                                             carbon-carbon
                                             triple bond stretch
                  40


                  20


                   0
                    4000       3500   3000   2500         2000     1500   1000   500
                                             Wavenumbers, cm-1


                        neat liquid
                     100
                     90
                     80
   % Transmittance




                     70
                     60
                                                                                  
                     50                                           overtones of
                                                                  the benzene    
                     40                                 3         ring
                              sp2 C-H stretches       sp C-H stretches
                     30
                     20
                                                                                    
                       4000     3500          3000      2500         2000        1500   1000
                                                                         -1
                                                     Wavenumbers, cm


The following is a liquid hydrocarbon
                  100


                  80
% Transmittance




                  60


                  40


                  20       Top: CHCl3 vs CHCl3
                           Bottom: 5% in CHCl3

                   0
                    4000       3500       3000   2500      2000      1500   1000   500
                                                 Wavenumbers, cm-1



                  The compound contains nitrogen
                   100


                   80
 % Transmittance




                   60


                   40


                   20


                     0
                     4000   3500   3000   2500     2000       1500   1000   500
                                          Wavenumbers, cm-1




Compound contains C, H, O

				
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