Chem 220 - Organic Chemistry
Problem Set 3 -Solution Set
Chapter 4, Chemical Reactions
Due: Monday, September 28, 2009
The prevailing theory of organic
structure in the early 19th century was Dualism or the
Electrochemical Theory, principally championed by
Berzelius.
Since inorganic sodium chloride could be considered as
Na+Cl-, then an alkyl halide such as
RCl could be thought of as R+Cl-. The
R group or "radical" of its day, was thought to be
immutable, the carbons and hydrogens behaving as though they
were an element. Liebig
(German) and Dumas (French), influential chemists of the
day, published a joint paper (1837), On
the Present State of Organic
Chemistry, extolling the
concept and claiming all that was left to do in organic
chemistry was to identify these immutable radicals (benzoyl,
ethyl, acetyl, etc.) As the story goes, a Parisian reception
at the Tuileries
was to change all of this. [The Tuilerie Gardens was
one of the images in Mussorgsky's "Pictures at an an
Exhibition", composed in 1874 for piano and later
orchestrated by Ravel. The Tuileries selection is
here.
For the history of this composition and background music, go
here.
(At
Yale, try this.]
The guests were discomforted by fumes from the burning
candles. Dumas was called in as a consultant. He found that
the waxes (fatty esters) had exchanged chlorine for
hydrogen, the culprit being the by-product hydrogen
chloride. [This story is likely apocryphal. It was
told by August
Hofmann at a eulogy for
Dumas (1884). If the event did occur, it is more likely that
the bleaching of candle wax involved addition of chlorine to
double bonds. Nonetheless, Dumas did investigate
substitution reactions.]