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NMRPredict Help
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Selecting Solvents
This option is found under Predict - Options - Carbon Solvents
Database records have been grouped into 29 major solvent headings. The more common and default solvents are shown in blue.
It is possible to select and de-select solvent groups prior to carbon prediction. As you select and de-select you can see exactly how many database records will be used for prediction.
If you de-select a default solvent, or select a non-default solvent, it will be highlighted in red as a warning.
It is strongly recommended to use the default solvents.
To demonstrate the dramatic effect solvent selection can have look at the example below.
The screen below shows a prediction for benzene using the default solvents. It can be seen that 45 records
are used for prediction even though there are 56 exact matches for benzene in the database.
The records measured in the more obscure solvents are not used and a reasonable prediction value of 128.5 ppm is obtained.
The screen below shows a prediction for benzene using all solvents.
Now all 56 identical structures are used for prediction, including all the obscure solvents.
The prediction now jumps to 131.3 ppm. Notice that there are now warnings about the difference between the HOSE code values and the Neural Network values
and the difference between the minimum and maximum values found in the database at 5 shells.
The screen below shows a prediction for benzene using only Lewis-acid type solvents.
Only 13 records are used for prediction and the prediction now jumps to 141.6 ppm!
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