Hydrogen deficiencies

The H C ratio in hydrocarbons is indicative of the hydrogen deficiency of the system. As mentioned, the highest theoretical H C ratio possible for hydrocarbon is 4 (in CH4), although in electron-deficient carbocationic compounds such as CH5 and even CH/, the ratio is further increased (to 5 and 6, respectively, see Chapter 10). On the other end of the scale in extreme cases, such as the dihydro- or methylene derivatives of recently discovered Cgo and C70 fullerenes, the H C ratio can be as low as 0.03. 

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... 

Bitumen is a hydrogen-deficient oil that is upgraded by carbon removal (coking) or hydrogen addition (hydrocrackiag) (2,4). There are two methods by which bitumen conversion can be achieved by direct heating of mined tar sand and by thermal decomposition of separated bitumen. The latter is the method used commercially, but the former has potential for commercialisation (see Fuels, SYNTHETIC). 

Aside from the above reforming reactions, a small amount of feed components are converted to polymeric hydrogen deficient products which deposit on the catalyst as "coke." A coke buildup results in activity and selectivity loss which ultimately requires catalyst regeneration. In semi-regenerative operation, the coking rate is maintained at a low level to provide cycles of at least three to six months. In cyclic units, coking conditions are inherently much more severe so that frequent regenerations are required. 

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. 

Risers are normally designed for an outlet vapor velocity of 50 ft/sec to 75 ft/sec (15.2 to 22.8 m/sec). The average hydrocarbon residence time is about two seconds (based on outlet conditions). As a consequence of the cracking reactions, a hydrogen-deficient material called coke is deposited on the catalyst, reducing catalyst activity. 

Coke is a hydrogen deficient residue left on the catalyst as a by-product of catalytic reactions. 

Hydrogen Transfer is the secondary reaction that converts olefins (predominantly iso-olefins) into paraffins while extracting hydrogen from larger, more hydrogen-deficient molecules. 

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. 

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