Index of hydrogen deficiency

Frequently, a great deal can be learned about an unknown substance simply from knowledge of its molecular formula. This information is based on the following general molecular formulas  

When the molecular formula for a compound contains noncarbon or nonhydrogen elements, the ratio of carbon to hydrogen may change. Following are three simple rules that may be used to predict how this ratio will change  

To convert the formula of an open-chain, saturated hydrocarbon to a formula containing Group V elements (N, P, As, Sb, Bi), one additional hydrogen atom must be added to the molecular formula for each such Group V element present. In the following examples, each formula is correct for a two-carbon acyclic, saturated compound  

FIGURE 1.2 Formation of rings and double bonds. Formation of each ring or double bond causes the loss of 2H. 

Notice that each time a ring or a r bond is introduced into a molecule, the number of hydrogens in the molecular formula is reduced by two. For every triple bond (two n bonds) introduced into a molecule, the number of hydrogens in the molecular formula is reduced by four. 

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Other terms that mean the same thing as the index of hydrogen deficiency include elements of unsaturation sites of unsaturation and the sum of double bonds and rings... 

The relatronshrp between molecular formulas multiple bonds and nngs rs referred to as the index of hydrogen deficiency and can be expressed by the equatron... 

Index of hydrogen deficiency (Section 13 23) A measure of the total double bonds and nngs a molecule contains It is determined by comparing the molecular formula C Hj. of the compound to that of an alkane that has the same number of carbons according to the equation... 

A molecule that has a moleculai fonnula of C7H14 has an index of hydrogen deficiency of 1 ... 

A molecule of moleculai fonnula C7H12 has four fewer hydrogens than the cone-sponding alkane. It has an index of hydrogen deficiency of 2 and can have two rings, two double bonds, one ring and one double bond, or one triple bond. 

Molecular Formulas of Hydrocarbons The Index of Hydrogen Deficiency... 

The index of hydrogen deficiency is defined as the number of pair of hydrogen atoms that must be subtracted from the molecular formula of the corresponding alkane to give the molecular formula of the compound under consideration. 

H2 = difference = 1 pair of hydrogen atoms Index of hydrogen deficiency = 1... 

The index of hydrogen deficiency can be calculated for compounds containing carbon, hydrogen, nitrogen, halogen, oxygen, and sulfur from the formula... 

Index of hydrogen deficiency = 4 per benzene ring and 1 per N02 group.)... 

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