Could someone please explain the definition of "achiral"? I understand that crystal structures can be chiral, but they can be described in either chiral or achiral space groups. I've come across publications on this topic, but I still don't fully understand the difference between achiral, non-chiral, or "no chiral."
Could it be that one of these forms is simply incorrect and should not be used?
Thanks in advance!
Dear Armand Budzianowski ,
there is no difference in the terms 'achiral' and 'non-chiral'.
See for example:
https://en.wikipedia.org/wiki/Chirality
There it is stated:
"A non-chiral object is called achiral (sometimes also amphichiral) and can be superposed on its mirror image"
See also for example
page 4 of:
https://instruct.uwo.ca/chemistry/020/workentin/organic%20unit%203-2%20page.pdf
as well as page 31 and 33
of
http://burton.chem.ox.ac.uk/introduction-to-organic.pdf
Best regards
G.M.
I agree with Gerhard Martens, and intuitively I would ssugest that they mean the same, but I cannot exclude subtle differences. To some extent scientific notions have developed anarchically/chaotically. In many cases there are no codified rules, or if there are some, they are often not obeyed. Ideally, the scientific community comes to an agreement in terms which is enforced by the reviewing system (which does not always work). One attempt to codify rules are the activities of IUPAC in chemistry, and there might be a chance that they have dealt with this issue.
If one finds these two terms at isolated places in a non-contradicting use, it is really difficult to exclude that these terms might, nevertheless, a different meaning. A way to find it out places in literature, where both terms are used and it is either stated that they are equivalent or the difference is elaborated (e.g. in a IUPAC report). It is, e.g., the Burton reference, which explicitly suggests that both terms mean the same, although sometimes it requires very special cases where difference between two terms get relevant.