cht - chemtool drawings analyzer
is a commandline tool to derive the sum formula and molecular mass of
the molecule depicted in a chemtool
drawing file. It is also available
from within chemtool
to calculate these data for the current structure
or a marked fragment of it.
currently recognizes the element symbols C, H, O, N, P, S, Si, B, Br,
Cl, F, I, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Ge, In, K, Li,
Mg, Mn, Na, Ni, Pb, Rb, Sb, Sc, Se, Sn, Sr, Te, Ti, Tl, V, Zn (that is, all
main group elements except the noble gases, and the first row of transition
metals) and the abbreviations Ac, Ade, Bn, Bu, iBu, tBu, Bz, BOC, Cyt, CE,
DBAM, DMAM, DMTr, Et, Gua, Me, Ms, MOC, MOM, MMTr, Ph, Pr, iPr, Tf, Thy, Tol,
Tr, Ts, TBDMS, TBDPS, TMS, TMTr, Ura, Z.
It can handle two levels of parentheses; e.g. P[OCH(CH_3)_2]_3.
detects any duplicate (overlapping) bonds in the drawing file,
it will prepend an exclamation mark to the calculated (and likely wrong) sum
understands the following options:
- -h, --help
- Displays brief help and list of options.
- -e, --exact
- Calculate exact mass for MS.
- -v, --verbose
- Be verbose.
- -d, --debug
- Be extremely verbose.
can misinterpret molecules that contain the 'aromatic ring' symbol,
as it uses a fixed search radius to identify the aromatic system that it
denotes. It also does not handle the 'partial double bond', so you should
avoid these two in drawings that you intend to use with cht
A label that is offset from the corresponding bond end by more than five pixels
is not recognized, so that the default CH2 or CH3 group enters the calculation
in its place.
In general, one should check the plausibility of the generated sum formula