gbranden pushed a commit to branch master
in repository groff.
commit bd0d3d8964e40391e7e8263a9041047c6d5b52a8
Author: Norwid Behrnd <[email protected]>
AuthorDate: Thu Jan 1 13:35:01 2026 +0100
[chem]: Improve ethamivan visual representation.
* contrib/chem/examples/ethamivan.chem: Improve visual representation.
Reorganize representation of the structure.
- Contract the hydroxyl group, both simplifying the definition of the
substituent and correcting the unusual dihedral angle of 180 degrees
about C-O-H previously used.
- Adjust orientations of the drawing overall and substituents (e.g.,
rules GR-3.1.2, GR-3.1.3; 3.2.1 in [1]), especially alkyl chains
around N (GR-4.1.1, ibid.).
...as one would "clean" the structure drawing in a GUI-based editor, and
indeed with a result very similar to the current depiction on
Wikipedia.[2]
Fixes <https://savannah.gnu.org/bugs/?67876>.
[1] Brecher, J. Graphical Representation Standards for Chemical
Structure Diagrams (IUPAC Recommendations 2008). Pure Appl. Chem.
2008, 80 (2), 277-410. https://doi.org/10.1351/pac200880020277.
[2] https://en.wikipedia.org/wiki/Etamivan
Signed-off-by: Norwid Behrnd <[email protected]>
---
contrib/chem/ChangeLog | 23 +++++++++++++++++++++++
contrib/chem/examples/ethamivan.chem | 21 ++++++++++-----------
2 files changed, 33 insertions(+), 11 deletions(-)
diff --git a/contrib/chem/ChangeLog b/contrib/chem/ChangeLog
index ff76cc5ee..fe5714c09 100644
--- a/contrib/chem/ChangeLog
+++ b/contrib/chem/ChangeLog
@@ -1,3 +1,26 @@
+2026-01-01 Norwid Behrnd <[email protected]>
+
+ * examples/ethamivan.chem: Improve visual representation.
+ Reorganize representation of the structure.
+ - Contract the hydroxyl group, both simplifying the definition
+ of the substituent and correcting the unusual dihedral angle
+ of 180 degrees about C-O-H previously used.
+ - Adjust orientations of the drawing overall and substituents
+ (e.g., rules GR-3.1.2, GR-3.1.3; 3.2.1 in [1]), especially
+ alkyl chains around N (GR-4.1.1, ibid.).
+
+ ...as one would "clean" the structure drawing in a GUI-based
+ editor, and indeed with a result very similar to the current
+ depiction on Wikipedia.[2]
+
+ Fixes <https://savannah.gnu.org/bugs/?67876>.
+
+ [1] Brecher, J. Graphical Representation Standards for Chemical
+ Structure Diagrams (IUPAC Recommendations 2008). Pure Appl.
+ Chem. 2008, 80 (2), 277-410.
+ https://doi.org/10.1351/pac200880020277.
+ [2] https://en.wikipedia.org/wiki/Etamivan
+
2025-12-31 Norwid Behrnd <[email protected]>
* examples/cholesterol.chem: Add stereochemistry.
diff --git a/contrib/chem/examples/ethamivan.chem
b/contrib/chem/examples/ethamivan.chem
index cdf3e33de..ba47118ac 100644
--- a/contrib/chem/examples/ethamivan.chem
+++ b/contrib/chem/examples/ethamivan.chem
@@ -3,22 +3,21 @@ ethamivan.chem:
# Example file for chem:
# Ethamivan or Analepticon or C12_H17_N_O3 or
-# N,N-diethyl-4-hydroxy-3-methoxy-benzamide
+# N,N-diethyl-4-hydroxy-3-methoxy-benzamide (CAS-RN: 304-84-7)
#
# Prepared by Bernd Warken <[email protected]>.
-R: ring pointing left double 2,3 4,5 6,1
- bond left from R.V1 ; O
- bond left ; H
- bond -150 from R.V6 ; O
- bond left
- bond 60 from R.V4
+R: ring6 pointing 60 double 1,2 3,4 5,6
+ bond 60 from R.V1
B1: double bond up ; O
bond 120 from B1.start ; N
- bond 45
- bond right
- bond 135 from N
- bond right
+ bond 60
+ bond 120
+ bond down from N
+ bond 120
+ bond -120 from R.V4 ; HO
+ bond -60 from R.V5 ; O
+ bond -120
# Local Variables:
# fill-column: 72
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