NMR Testing Laboratory

Industrial NMR Spectroscopy Applications

Table 4 13C Average Molecule Param

Table 4 13C NMR derived Average Molecule Parameters
General Carbon Types:
Aromatic Carbon Atomic percent of carbons in aromatic groups.
Aliphatic Carbon Atomic percent of carbons in naphthenic or paraffinic components.
Carboxylic/Carbonyl Carbon Atomic percent of carbons in carboxylic acids, esters, amides, ketones or aldehyde groups.
Protonated Aromatic Carbon Atomic percent of aromatic carbons with hydrogen attached.
Alkyl-Substituted Aromatic Carbon Atomic percent of aromatic carbons with alkyl groups attached.
Methine Carbon Atomic percent of aliphatic (naphthenic or paraffinic) methine carbons.
Methylene Carbon Atomic percent of aliphatic (naphthenic or paraffinic) methylene carbons.
Methyl Carbon Atomic percent of aliphatic (naphthenic or paraffinic) methyl carbons.
Aromatic Carbon Breakdown:
Carbonyl Carbon Atomic percent carbon present as aldehydes and ketones.
Carboxyl Carbon Atomic percent carbon present as esters, amides, acids and anhydrides.
Heteroaromatic Carbon Atomic percent carbon present as aromatic carbon adjacent to nitrogen, sulfur, or oxygen.
Methylene/Methine-Substituted Aromatic Carbon Atomic percent carbon present as aromatic carbon substituted by an alkyl group through a methine or methylene carbon.
Naphthene-Substituted Aromatic Carbon Atomic percent carbon present as aromatic carbon substituted by naphthenic carbon groups.
Methyl-Substituted Aromatic Carbon Atomic percent carbon present as aromatic carbon substituted by a methyl group.
Internal Aromatic Carbon Atomic percent carbon present as bridgehead aromatic carbons in polynuclear aromatics.
Methyl Carbon Atomic percent of aliphatic (naphthenic or paraffinic) methyl carbons.
Naphthenic Carbon Breakdown:
Total Naphthenic Carbon Atomic percent carbon present as naphthenic (cyclic aliphatic) carbon.
Naphthenic Methine Carbon Atomic percent carbon present as methines in naphthenic ring systems.
Naphthenic Methylene Carbon Atomic percent carbon present as methylene in naphthenic ring systems.
Naphthenic Methyl Carbon Atomic percent carbon present as methyls attached to naphthenic ring systems.
Paraffinic Carbon Breakdown:
Paraffinic Carbon Atomic percent carbon present as paraffinic carbon.
N-Paraffin Character of Sample Atomic percent carbon present as paraffinic methyls and methylenes in uninterrupted straight paraffin chain sequences.
N-Paraffin Character of Paraffins Percent of the paraffinic carbons themselves that are present in uninterrupted straight paraffin chain sequences.
Degree of Branching in Paraffins This is a ratio comparison of branching paraffinic carbons against straight chain paraffins. The higher the ratio the more branched the paraffinic carbon component of the sample.
Average Paraffin Straight Chain Length Average length of uninterrupted methylene sequences in paraffinic chains, i.e. takes into account length of methylene sequences in all N-paraffins, isoparaffins and branched paraffins. This should not be confused with wax content which cannot be determined by NMR of a bulk sample.
Average Molecule Description:
Mole Fraction of Bridgehead Aromatics Ratio of bridgehead aromatic carbon content with total aromatic carbon content.
Average Number of Aromatic Carbons per Cluster Number of carbon atoms in the average aromatic cluster, i.e. 6 = single ring, 10 = naphthalene, 14 = anthracene, 18 = pyrene, etc. This is calculated from the Mole Fraction of Bridgehead Aromatics assuming linear concatenation of the aromatics.
Average Number of Aromatic Clusters per 100 Carbons Simply the total aromatic carbon percentage divided by the average number of aromatic carbons per cluster. This number is needed to obtain the average functional group makeup of the “average” molecule in the sample.
Average Number of Alkyl Substitutions per Aromatic Cluster Average number of alkyl (naphthenic or paraffinic) substitutions on the average aromatic cluster.
Average Number of Methyl Substitutions Per aromatic Cluster Average number of methyl groups attached directly to the aromatic cluster.
Average Number of Napthenic Substitutions per Cluster Average number of aromatic carbons substituted by a naphthenic carbon (methine or methylene).
Average CH2/CH Substitutions per Cluster Average number of aromatic carbons substituted by a paraffinic carbon (methine or methylene).
Average Number of Heteroatoms per Cluster Average number of N, S, or O atoms per aromatic cluster.
Average Number of Naphthenic CH3 per Cluster Average number of methyl carbons attached to naphthenic ring systems.
Average Number of Naphthenic Rings per Cluster Average number of naphthenic rings attached to the average aromatic cluster. This is based on the total napthenic carbon content and assuming all the rings are 6-membered.
Average Number of Paraffinic Carbons per Cluster Average number of paraffinic carbons substituted onto the average aromatic cluster. This is simply the total paraffin content divided by the number of aromatic clusters per 100 carbons. NMR cannot distinguish between alkyl-aromatics with long paraffinic groups and totally paraffinic molecules. This number should be contrasted with the Average Paraffin Straight Chain Length parameter.
Average Chain Length of Paraffinic Substitutions This number is obtained by dividing the Average number of paraffins per aromatic cluster by the number of CH/CH2 substitutions per cluster. Obviously this number is not realistic and should also be contrasted with the Average Paraffin Straight Chain Length parameter.