Step 1 - Enter build mode
From the Tools menu, choose Tools:Build to enter into build mode. This will allow the
addition of atoms to create the acrolein molecule.
Step 2 - Add carbon backbone
From the Build menu, choose Build:C to select carbon as the active atom. Singe click
somewhere near the center of the editor window to add a single carbon atom. Click and
drag from this carbon atom to an empty spot on the editor pane to add a new carbon atom,
bonded to the first. Click and drag from this second at to yet another
blank area to add a third carbon atom, bonded to the second. Click and drag from C2 to C3
to add a double bond between C2 and C3.
Step 3 - Add oxygen atom and double bond
From the Build menu, choose Build:O to select oxygen as the active atom. Click on C1
and drag to a blank area on the editor pane to add a new oxygen atom, bonded to C1.
Click and drag from C1 to the oxygen atom to add a double bond.
Step 4 - Clean-Up
From the Clean-Up Menu choose, Clean-Up:Comprehensive. This will add hydrogen atoms to the
unfilled valencies, set hybridizations, and set bond angles based on those hybridizations.
Step 5 - Adjust dihedral angle
Clean-Up leaves the O-C1-C2-C3 dihedral angle in an unpredictable state (conjugation is
not taken into account). Thus, we must set this dihedral angle to 180o.
From the Tools menu, choose Tools:Adjust to enter into adjust mode. Click on the oxygen atom.
While holding down the SHIFT key, click on C1, followed by C2, and finally C3.
Notice that the current dihedral angle is displayed in the status bar.
Choose Adjust:Dihedral Angle from the menu bar. In the resulting dialog, enter a angle
of 180 degrees, and click OK. The molecule is complete.