Decoupled, NOE Double Resonance and COSY Spectra

If it is not obvious which protons in a molecule are coupled to which, 

The acronym COSY stands for Correlated SpectroscopV and this technique is widely used to determine all of the coupling interactions in a single experiment. This proves to be more efficient than the decoupling experiment in which each signal is irradiated in turn to determine its coupling partners. COSY involves a multiple pulse sequence (which we do not need to know anything about in order to use the technique) and is an example of two-dimensional (2D) spectroscopy. 

As all the coupling relationships in the molecule are given in the COSY spectrum, it is normal to be able to deduce all of the structural fragments in a molecule from the HH COSY spectrum. 

The % enhancement is found by dividing the height of ihe integral for the peak of interest by the value for IH. and multiplying by 100 For the peak at fi 4 42. this gives an enhancement of 5,9% (the maximum value is 50% but usual values are between 1 and 20%.  

Once again, there is a 2D version of this experiment which gives all 

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