ChatGPT's answer contains some correct information,
but it is not "fine". It is incomplete and it can lead many readers to
First, ChatGPT provides
an incomplete description of methylamine, "one nitrogen atom and one
methyl group". That phrase adds up to N-CH3. 2 H atoms are
fails to describe either of these participants properly. It only mentions one
property of the nitrogen (lone pair), and it does not describe any required
hydrogen (see below).
Nitrogen properties. ChatGPT
mentions lone pairs. Unfortunately, lone pairs are not a sufficient basis for
an answer. F in HF has 3 lone pairs but is a weak hydrogen bond acceptor,
whereas F in F anion (4 lone pairs) is
a much stronger hydrogen bond acceptor. But don't be misled because Ne
(also 4 lone pairs) is not a hydrogen bond acceptor. We cannot simply rely on
Hydrogen properties. ChatGPT mentions
"hydrogen". That is correct. Hydrogens
are always found in hydrogen bond donors, but not every hydrogen atom forms
hydrogen bonds. Usually the hydrogen must carry a partial positive
charge, and this is usually achieved by H being bonded to a more
electronegative atom. ChatGPT does not even specify which hydrogen
participates in the hydrogen bond. While it is tempting to assume that
it's implied because the
hydrogen bond occurs between methylamine and pyrazine, that doesn't do the
job because ChatGPT's description
of methylamine is incomplete. It states only that "the
hydrogen atom in methylamine can form a hydrogen bond", but there are 5 H
in methylamine. ChatGPT seems to think there are only 3H because it says
methylamine contains "one nitrogen atom and one methyl
Here's another ChatGPT
example that reached me a few weeks ago that has no bearing on this thread's
conversation around H bonding. A chemistry teacher and friend (who will
remain anonymous) asked ChatGPT to "explain the NMR spectrum of
ethyl acetate" and sent me ChatGPT's
common organic compound with the chemical formula CH3COOCH2CH3. Its
nuclear magnetic resonance (NMR) spectrum displays characteristic peaks
corresponding to the different types of protons present in the molecule.
In the proton NMR spectrum of ethyl acetate,
there are four types of protons: the two methyl group protons (CH3),
the methylene group proton adjacent to the carbonyl (C=O) group (CH2),
and the carbonyl group proton (C=O). The chemical shifts and splitting
patterns of these protons are as follows:
• The two methyl group protons appear as a singlet peak at
1.25 ppm (parts per million), which is typical of alkyl methyl protons.
• The methylene group proton adjacent to the carbonyl group
as a triplet peak at around 4.1 ppm, with a coupling constant of about 7
Hz. This triplet splitting arises from the coupling of the methylene
proton with the two equivalent methyl group protons.
• The carbonyl group proton appears as a singlet peak at
around 2.05 ppm, which is typical of carbonyl protons.
Overall, the NMR spectrum of ethyl acetate
displays four peaks, each corresponding to a different type of proton
in the molecule. By analyzing the chemical shifts and splitting patterns
of these peaks, it is possible to identify the different types of
protons in ethyl acetate and obtain information about
the molecular structure and bonding.
so-called explanation (much like the previous one regarding methylamine and
pyrazine) is a mixed bag. There is good and there is bad. And even when there is
good, ChatGPT uses it incorrectly.
Example of good
info: a correct formula for ethyl acetate.
of bad inferences:
- "carbonyl group proton"
does not exist in this molecule
are six, not "two" methyl group protons in the
- the formula shows two methylene group protonS,
not a "methylene group proton"
- the methyl
groups are inequivalent and produce signals at different chemical shifts whereas
ChatGPT says there is one signal that is due to "two methyl group
protons" and describes them both as "alkyl methyl protons"
(actually, one is an alkyl methyl, the other is an acyl methyl)
- many errors
in the coupling patterns and explanations of
And a final
conclusion that is highly misleading:
- "the NMR
spectrum of ethyl acetate displays four peaks"
There are actually 3 types of protons, and they produce these signal patterns: a
singlet (1 peak), a triplet (3 peaks) and a quartet (4 peaks) for a total of 8
ChatGPT's conclusion (4 peaks) doesn't
even agree with its own analysis. It lists 3 types of protons, and identifies
them as producing two singlets + one triplet -> 3 signals or 5
Obviously, this is
a much worse example of ChatGPT's abilities than the previous one, but I
think they have much in common. Tread