FAQ - ChemNMR

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Standard Deviations
Stereochmistry
Conformational Effects
Negative Charges
Maximum Molecules

How accurate is the ChemNMR 5.0 calculation?

Mean standard deviations between predicted and measured chemical shifts are in the order of 0.2-0.3 ppm for 1H-NMR and of 4-5 ppm for 13C-NMR.

Does ChemNMR 5.0 take into account stereochemistry so that diastereomers can be determined based on the NMR data predictions?

ChemNMR takes only into account stereochemistry of double bonds (Z,E) and of cyclohexane (axial/equatorial, if the chair form is drawn as input) but not in other cases.

It seems ChemNMR 5.0 cannot distinguish conformational effects. Is this true and is a more powerful version being prepared?

Only the conformational effects of cyclohexane chairs are supported by the current version. There are plans to extend the features towards conformational and stereochemical effects. However this can't be done merely by enhancing the applied model because it is based upon linear addition of substituent effects. Other approaches will have to be integrated.

How do I get proton shift data when I have negative charges in the molecule i.e. carboxylate, RCOO-?

Negative charges shouldn't be a problem whatsoever. You can enter the O- in the carboxylate as "O-". NB: "COO-" may not be entered as label. You have to draw the carboxylate substructure.

How many molecules can be used at maximum with ChemNMR 5.0?

The limiting factor is the application runtime memory. On Mac, the user can easily enlarge it. It also depends on the complexity of the molecules, e.g. condensed rings need much more memory than chains.

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	If you don't find what you're looking for below, please submit your question to info@upstream.ch, thank you.
Standard Deviations Stereochmistry Conformational Effects Negative Charges Maximum Molecules	How accurate is the ChemNMR 5.0 calculation? Mean standard deviations between predicted and measured chemical shifts are in the order of 0.2-0.3 ppm for 1H-NMR and of 4-5 ppm for 13C-NMR.
	Does ChemNMR 5.0 take into account stereochemistry so that diastereomers can be determined based on the NMR data predictions?
	ChemNMR takes only into account stereochemistry of double bonds (Z,E) and of cyclohexane (axial/equatorial, if the chair form is drawn as input) but not in other cases.
	It seems ChemNMR 5.0 cannot distinguish conformational effects. Is this true and is a more powerful version being prepared?
	Only the conformational effects of cyclohexane chairs are supported by the current version. There are plans to extend the features towards conformational and stereochemical effects. However this can't be done merely by enhancing the applied model because it is based upon linear addition of substituent effects. Other approaches will have to be integrated.
	How do I get proton shift data when I have negative charges in the molecule i.e. carboxylate, RCOO-?
	Negative charges shouldn't be a problem whatsoever. You can enter the O- in the carboxylate as "O-". NB: "COO-" may not be entered as label. You have to draw the carboxylate substructure.
	How many molecules can be used at maximum with ChemNMR 5.0?
	The limiting factor is the application runtime memory. On Mac, the user can easily enlarge it. It also depends on the complexity of the molecules, e.g. condensed rings need much more memory than chains.