how can you identify a specific unknown aldehyde or ketone?

---

Request for Question Clarification by andrewxmp-ga on 19 Jul 2004 14:29 PDT

Between the various kinds of spectroscopy (the most useful being
infared or NMR analysis) much information about the structure of a
compound can be accurately deduced.  Would you like general
information about how this is done, and how it might be applied to a
ketone or aldehyde, or are you looking for info about other (not
necessarily spectroscopic) methods?

---

Clarification of Question by stef44-ga on 19 Jul 2004 19:58 PDT

i meant testing them with chemical compounds in a regular school lab, where 
reactions would happen; example: change of color, precipitation, etc..

---

Request for Question Clarification by andrewxmp-ga on 19 Jul 2004 21:03 PDT

There are some experiments that can be done that could be used to tell
if something is a ketone or an aldehyde, because usualy those
particular functional groups are the basis for the experiment. 
However, it would probably be much more difficult to determine the
specific structure of two different compounds withhin those classes
without spectroscopy...

http://www.chemistry.ccsu.edu/glagovich/teaching/472/qualanal/tests/tests.html

My chemistry is a bit foggy, but you could perform a test with
hydroxylamine hydrochloride.    This should provide a color change if
the test is positive.

Ironically, the site dr_bob-ga provided has some good details on this test.

http://www.chemistry.ccsu.edu/glagovich/teaching/472/qualanal/tests/hydroxylamine.html

Hope this helps.

silver,

This reagent is not just hydroxylamine hydrochloride, it has some kind
ofindicator to go with it(probably acid base, since the reaction would
liberate free hcl+oxime), as going from ketone or aldehyde to oxime
does not always produce a color change in the compound of interest.