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It turns out that organic chemists have developed methods to estimate
boiling point from structural features of an organic molecule.
Features are assigned values ( Boiling Point Numbers or bpns)
which are totaled and entered in a table of boiling points
which depend on the cube root of the sum of bpns
in this way:
BP = 230.14 * (bpn)^(1/3) - 543 (degC).
Most bpns are positive:
Carbon in the main chain - 0.8 (each)
Hydrogen attached to the main chain 1.0 (each)
a saturated butyl radical in the main chain rates 9.7
an alcohol - OH like R CH2OH rates 10.8
an acid - COOH like R CH2COOH rates 19.3
...but there *is* at least one structure that collects a negative rating:
A saturated radical attached to the main chain of the sort
described as a 2,2-dimethyl group rates -0.4
This method can often estimate bp to within 1 to 4 degC
(following Lange's HB of Chemistry)
Brian Whatcott Altus OK
At 09:55 AM 5/17/2003 -0400, you wrote:
Yes, Alcohols hydrogen bond - just not as well as water since there are
so many other atoms to get in the way of the alcoholic hydrogen
reaching the oxygen. Methanol is a liquid at room temperature even
though its molecular weight is 32 g/mole, which is still pretty small
for a liquid. H2S is 34 g/mole and is quite obviously a gas at room
temp.
Steve Clark
Friday, May 16, 2003, at 10:27 PM, Bernard Cleyet wrote:
Alcohol works fine too. Problem; I used the kind that has 5% water.
-- I wonder, do alcohols hydrogen bond -- HCl does.
bc
p.s. just tried kerosene; works fine
John Barrer wrote:
Don't wet curtains stick to surfaces so well b/c the
liquid excludes air between the surface and the
curtain? Isn't there just as much "stickiness" if ANY
liquid (hydrophilic or hydrophobic) is used as the
wetting agent? John Barrere