Molecular weight nitrogen rule

The nitrogen rule states that if a molecule has an odd number of nitrogen atoms, it will have an odd molecular weight. The rule derives from the fact that nitrogen is unique among common elements/isotopes in having an odd valency but an even atomic number. Figure 5.20 shows the mass spectrum of aniline, with M+ at m/z 93. 

A relatively simple example is the nitrogen rule A molecule with an odd number of nitrogens has an odd molecular weight a molecule with only C H and O or with an even number of nitrogens has an even molecular weight... 

Nitrogen rule (Section 13 23) The molecular weight of a sub stance that contains C H O and N is odd if the number of nitrogens is odd The molecular weight is even if the num her of nitrogens is even... 

The nitrogen rule of mass spectrometry says that a compound with an odd number of nitrogen atoms has an odd-numbered molecular weight. Thus, the presence of nitrogen in a molecule is detected simply by observing its mass spectrum. An odd-numbered molecular ion usually means that the unknown... 

Nitrogen rule (Section 24.10) A compound with an odd number of nitrogen atoms has an odd-numbered molecular weight. 

In addition to the study of the isotopic cluster, useful information on analyte identity can be obtained by the nitrogen rule. It states that if a molecule contains an odd number of nitrogen atoms, its molecular weight must be an odd number. However, if an even number of nitrogen atoms or no nitrogen is present, its molecular weight must be an even number. 

Many peaks can be ruled out as possible molecular ions simply on grounds of reasonable structure requirements. The nitrogen rule is often helpful. It states that a molecule of even-numbered molecular weight must contain either no nitrogen or an even number of nitrogen atoms an odd-numbered molecular weight requires... 

The effect of N atoms on the mass of the molecular ion in a mass spectrum is called the nitrogen rule A compound that contains an odd number of N atoms gives an odd molecular ion. A compound that contains an even number of N atoms (including zero) gives an even molecular ion. Two street drugs that mimic the effects of heroin illustrate this principle 3-methylfentanyl (two N atoms, even molecular weight) and MPPP (one N atom, odd molecular weight). 

Vitamins are vital (= vita) and mainly nitrogenous (= amines) substances of low-molecular weight. As a rule, they must be present in the diet as essential components. Only a few vitamins (e.g. A, K, Bi, B5, B12, folic acid, biotin) are formed in the intestine by bacteria. Plants constitute the main source of exogenous vitamin supply. In a biochemical context, the principal bio-catalytic effect of vitamins consists in substituting cofactors of enzymes which have undergone metabolic degradation. 

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