How to delete hydrogen atoms from molecule data during data conversion?

If hydrogen atoms of a molecule are included in the input data source, you can use the "babel" generic option "-d" remove those hydrogen atoms during the molecule data conversion process.

Here is an example of using the "-d" option in the "babel" command.

1. Generate a benzene molecule with hydrogen atoms included and stored in a "sdf" file.

fyicenter$ obabel -:c1ccccc1 -o sdf -O benzene.sdf --gen2D -h
1 molecule converted

fyicenter$ more benzene.sdf 

 OpenBabel05212009392D

 12 12  0  0  0  0  0  0  0  0999 V2000
   -0.8660   -0.5000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -1.7321   -0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -1.7321    1.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -0.8660    1.5000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -0.0000    1.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    0.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -0.8660   -1.5320    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
   -2.6258   -0.5160    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
   -2.6258    1.5160    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
   -0.8660    2.5320    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
    0.8937    1.5160    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
    0.8937   -0.5160    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
  1  6  1  0  0  0  0
  1  2  2  0  0  0  0
  1  7  1  0  0  0  0
  2  3  1  0  0  0  0
  2  8  1  0  0  0  0
  3  4  2  0  0  0  0
  3  9  1  0  0  0  0
  4  5  1  0  0  0  0
  4 10  1  0  0  0  0
  5  6  2  0  0  0  0
  5 11  1  0  0  0  0
  6 12  1  0  0  0  0
M  END
$$$$

2. Convert the benzene molecule from "sdf" format to "svg" format with hydrogen atoms deleted using the "-d" option:

fyicenter$ babel benzene.sdf -o svg -d

<?xml version="1.0"?>
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:cml="http://www.xml-cml.org/schema" 
width="149.283" height="159.999" x="0" y="0" font-family="sans-serif" 
stroke="rgb(0,0,0)" stroke-width="1"  stroke-linecap="round">
<rect x="0%" y="0%" width="100%" height="100%" stroke-width="0" fill="rgb(255,255,255)"  />
<line x1="74.6" y1="120.0" x2="40.0" y2="100.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="73.0" y1="110.8" x2="48.8" y2="96.8" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="40.0" y1="100.0" x2="40.0" y2="60.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="40.0" y1="60.0" x2="74.6" y2="40.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="48.8" y1="63.2" x2="73.0" y2="49.2" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="74.6" y1="40.0" x2="109.3" y2="60.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="109.3" y1="60.0" x2="109.3" y2="100.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="102.1" y1="66.0" x2="102.1" y2="94.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="109.3" y1="100.0" x2="74.6" y2="120.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<text font-size="18.000000" fill ="black" font-family="sans-serif"
x="10.000000" y="20.000000" ></text>
<title> - OBDepict</title>
</svg>

As you can see from the output, 6 hydrogen atoms were deleted from the benzene molecule, because of the "-d" option.

As a comparison, here is the output of the above "babel" command without the "-d" option:

fyicenter$ babel benzene.sdf -o svg

<?xml version="1.0"?>
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:cml="http://www.xml-cml.org/schema" 
width="218.564" height="240.001" x="0" y="0" font-family="sans-serif" 
stroke="rgb(0,0,0)" stroke-width="1"  stroke-linecap="round">
<rect x="0%" y="0%" width="100%" height="100%" stroke-width="0" fill="rgb(255,255,255)"  />
<line x1="109.3" y1="159.4" x2="109.3" y2="187.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="75.2" y1="139.7" x2="51.3" y2="153.5" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="75.2" y1="100.3" x2="51.3" y2="86.5" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="109.3" y1="80.6" x2="109.3" y2="53.0" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="143.4" y1="100.3" x2="167.3" y2="86.5" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="143.4" y1="139.7" x2="167.3" y2="153.5" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="109.3" y1="159.4" x2="75.2" y2="139.7" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="107.7" y1="150.1" x2="84.0" y2="136.4" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="75.2" y1="139.7" x2="75.2" y2="100.3" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="75.2" y1="100.3" x2="109.3" y2="80.6" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="84.0" y1="103.6" x2="107.7" y2="89.9" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="109.3" y1="80.6" x2="143.4" y2="100.3" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="143.4" y1="100.3" x2="143.4" y2="139.7" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="136.2" y1="106.3" x2="136.2" y2="133.7" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<line x1="143.4" y1="139.7" x2="109.3" y2="159.4" stroke="rgb(0,0,0)"  stroke-width="1.0"/>
<text x="103.283733" y="208.000619" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text x="34.000000" y="168.000464" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text x="34.000000" y="88.000155" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text x="103.283733" y="48.000000" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text x="172.563528" y="88.000155" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text x="172.563528" y="168.000464" fill="rgb(191,191,191)"  stroke="rgb(191,191,191)" stroke-width="1" font-size="16" >H</text>
<text font-size="18.000000" fill ="black" font-family="sans-serif"
x="10.000000" y="20.000000" ></text>
<title> - OBDepict</title>
</svg>

⇒ "babel --append ..." Command - Calculate Molecule Properties

⇐ "babel -h" Command - Add Hydrogens to Molecule Data

⇑ Understanding "babel" Command Line Syntax

⇑⇑ Open Babel Tutorials