How to Calculate J Coupling Constants


Coupling is a scientific term used to describe the interaction between protons. Coupling constant J is a specific way of expressing how these protons behave when this interaction occurs. When the behavior of these protons is mapped out on something called an NMR spectrum, the diagram reveals a series of peaks and valleys representing the strength of the protons' magnetic fields. The distance between these peaks is known as the coupling constant J.

Things You'll Need

  • Nuclear magnetic resonance spectroscope
  • Calculator
  • Gather the necessary data about the molecule. You will require access to measurements indicating the height of the molecule's NMR peaks in parts per million. This information can only be gathered with a nuclear magnetic resonance spectroscope. You will also need to know the strength of the NMR spectroscope in megahertz.

  • Convert each peak's parts per million into hertz. To do this, multiply each peak's parts per million by the strength of the NMR spectroscope. For example, if you had a peak that was measured at 3.632 ppm on a spectroscope operating at 500 mHz, you would multiply 3.632 by 500 to get 1816 hertz. This should be done individually for each of the peaks.

  • Find the difference in hertz between two of the peaks. To do this, subtract the hertz of one peak from the hertz of the other. The difference is the coupling constant J.


  • Photo Credit cocaine molecule 2 image by Yurok Aleksandrovich from
Promoted By Zergnet


You May Also Like

  • How to Calculate a Constant

    The derivative of a constant is zero, so when you integrate any function, the general solution contains an arbitrary constant. You must...

  • How to Calculate Proportionality

    The term "proportionality" means a ratio between two quantities that does not vary -- that is, the ratio remains constant. Proportionality is...

  • How to Determine Proton NMR Shifts

    Proton NMR (nuclear magnetic resonance) shifts incorporate magnetism and quantum physics. Protons respond to a magnetic field with two distinct energies, depending...

  • How to Calculate Hertz to Joules

    The metric (International) system defines a hertz (Hz) as a unit of frequency, while a joule (J) represents a unit of energy....

  • How to Calculate Spring Constant

    A spring constant is a physical attribute of a spring. Each spring has its own spring constant. The spring constant describes the...

  • How to Calculate Capacitance for AC Coupling

    An AC coupling capacitor connects the output of one circuit to the input of another. It is used to block the DC...

Related Searches

Check It Out

How to Build and Grow a Salad Garden On Your Balcony

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!