Using Spectroscopy to Determine a Structural Formula

Each of the following 'unknown' problems provides sufficient spectroscopic data to enable you to draw a structural formula, using the drawing window opened by the Draw Formulas button. When you are finished, Submit your formula and then check it by pressing the Check Molecule button. A help screen is available for the drawing window.


1. A compound composed of carbon, hydrogen & oxygen has a molecular ion at m/z=112 amu in its mass spectrum. The base peak is at m/z=28 amu. The infrared spectrum shows strong absorption in the 2850 to 2980 cm-1 region, and very strong absorption at 1717 cm-1. The 1H nmr shows a single sharp signal at δ = 2.7 ppm, and the 13C nmr has two signals ( δ = 37 & 208 ppm ).

    


2. A compound composed of carbon, hydrogen & oxygen has a molecular ion at m/z=90 amu in its mass spectrum. The base peak is at m/z=45 amu. The infrared spectrum shows strong absorption in the 2840 to 2980 cm-1 region, and very strong absorption from 1105 to 1125 cm-1. The 1H nmr shows two sharp signals at δ = 3.40 & 3.55 ppm (intensity ratio 3:2 respectively), and the 13C nmr also has two signals ( δ =59 & 72 ppm ).

    


3. A compound used as a moth repellant has three molecular ion peaks at m/z=146 (100%), 148 (65%) & 150 (10%) amu in its mass spectrum. A pair of smaller peaks are seen at m/z=111 (34%) & 113 (11%). The infrared spectrum shows sharp absorption just above 3000 cm-1 region, and also at 1480 cm-1. The 1H nmr shows a single sharp signal at δ = 7.2 ppm, and the 13C nmr has two signals ( δ =133 & 130 ppm ).

    


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This script written by William Reusch, Dept. of Chemistry, Michigan State University. Please send comments and corrections to whreusch@pilot.msu.edu.
JME Molecular Editor v2002.05 by: by Peter Ertl