gbranden pushed a commit to branch master
in repository groff.
commit ef5722908e00a958f70d73a0570e0dbd55aa9ec1
Author: Norwid Behrnd <[email protected]>
AuthorDate: Mon Jan 19 18:21:12 2026 -0600
[chem]: Fix Savannah #67929.
* contrib/chem/examples/reserpine.chem: Edit the visual representation
of the structure for aesthetic reasons.
- Contract substituents' labels where suitable;
- adjust bond angles; and
- complete the description of information about stereogenic centres
... in line with rules compiled by Brecher,[1] allowing a simpler and
shorter definition than the earlier one. Retain the orientation of the
overall molecule previously set because this matches the orientation of
yohimban one can refer as parental hydride depicted in appendix 3 of
IUPAC's Blue Book.[2,3]
[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] Nomenclature of Organic Chemistry: IUPAC Recommendations and
Preferred Names 2013; Favre, H. A., Powell, W. H.,
International Union of Pure and Applied Chemistry, Eds.; Royal
Society of Chemistry: Cambridge, 2014.
[3] https://iupac.qmul.ac.uk/BlueBook/
Fixes <https://savannah.gnu.org/bugs/?67929>.
[I added "End:" back into the GNU Emacs local variable region to assist
that text editor, and recast the ChangeLog entry to be in active voice,
which I understand to be more idiomatic in software engineering than the
passive voice we commonly observe in publications in the experimental
sciences. --GBR]
---
contrib/chem/ChangeLog | 25 +++++++++++++++
contrib/chem/examples/reserpine.chem | 62 ++++++++++++++++--------------------
2 files changed, 53 insertions(+), 34 deletions(-)
diff --git a/contrib/chem/ChangeLog b/contrib/chem/ChangeLog
index e394b19c9..b1cc4823f 100644
--- a/contrib/chem/ChangeLog
+++ b/contrib/chem/ChangeLog
@@ -1,3 +1,28 @@
+2026-01-18 Norwid Behrnd <[email protected]>
+
+ * examples/reserpine.chem: Edit the visual representation of the
+ structure for aesthetic reasons.
+ - Contract substituents' labels where suitable;
+ - adjust bond angles; and
+ - complete the description of information about stereogenic
+ centres
+
+ ... in line with rules compiled by Brecher,[1] allowing a
+ simpler and shorter definition than the earlier one. Retain the
+ orientation of the overall molecule previously set because this
+ matches the orientation of yohimban one can refer as parental
+ hydride depicted in appendix 3 of IUPAC's Blue Book.[2,3]
+
+ [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] Nomenclature of Organic Chemistry: IUPAC Recommendations and
+ Preferred Names 2013; Favre, H. A., Powell, W. H.,
+ International Union of Pure and Applied Chemistry, Eds.;
+ Royal Society of Chemistry: Cambridge, 2014.
+ [3] https://iupac.qmul.ac.uk/BlueBook/
+
2026-01-18 Norwid Behrnd <[email protected]>
* examples/morphine.chem: Resurrect, rewritting as a more
diff --git a/contrib/chem/examples/reserpine.chem
b/contrib/chem/examples/reserpine.chem
index becabebff..42dc2732a 100644
--- a/contrib/chem/examples/reserpine.chem
+++ b/contrib/chem/examples/reserpine.chem
@@ -1,45 +1,39 @@
reserpine.chem:
-.PS
-begin chem
+.cstart
# Example file for chem:
-# Reserpine or C33H40N2O9
+# Reserpine or C_33H_40N_2O_9 (CAS-RN: 50-55-5).
#
-# Prepared by Bernd Warken <[email protected]>.
+# Found at https://en.wikipedia.org/wiki/Reserpine
+#
+# Prepared by Bernd Warken <[email protected]>,
+# reorganized by Norwid Behrnd <[email protected]>.
+
+R1: ring6 double 1,2 3,4 5,6
+R2: flatring5 pointing down with .V2 at R1.V3 put N at 1 double 4,5
+R3: ring6 with .V5 at R2.V5 put N at 3
+R4: ring6 with .V1 at R3.V3 put N at 1 # prevent a struck-through N
+R5: ring6 with .V1 at R4.V3
+ frontbond 120 from R5.V3 ; O
+ bond 60
+BP: doublebond up ; O
+ bond 120 from BP.start
+R6: ring6 double 1,2 3,4 5,6
-R1: benzene pointing up
- bond -120 from R1.V5 ; O
- bond left
-R2: flatring5 pointing down double 4,5 with .V2 at R1.V3 with .V3 at R1.V2
put N at 1
- H below R2.V1
-R3: ring put N at 3 with .V5 at R2.V5
-R4: ring put N at 1 with .V1 at R3.V3
- back bond -120 from R4.V4 ; H
- back bond 60 from R4.V3 ; H
-R5: ring with .V1 at R4.V3
- bond -120
-D1: double bond down ; O
- bond left from D1.start ; O
- bond left
- back bond 60 from R5.V3 ; H
- back bond down from R5.V4 ; O
- bond down from O
- bond 120 from R5.V3 ; O
- bond 50 from O
-D2: double bond up ; O
- bond right length .1 from D2.start
-B: benzene pointing right
- bond 45 from B.V6 ; O
- bond right
- bond right from B.V1 ; O
- bond right
- bond 135 from B.V2 ; O
- bond right
+ bond -120 from R1.V5 ; MeO
+ H below R2.N
+ frontbond -120 from R3.V4 ; H
+ backbond 60 from R4.V3 ; H
+ backbond -120 from R4.V4 ; H
+ backbond down from R5.V4 ; OMe
+ frontbond -120 from R5.V5 ; MeO2C
+ bond 060 from R6.V2 ; OMe
+ bond 120 from R6.V3 ; OMe
+ bond 180 from R6.V4 ; OMe
# Local Variables:
# fill-column: 72
# mode: Nroff
# End:
# vim: set textwidth=72:
-end
-.PE
+.cend
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