Carbon chains, abbreviations isomers

They have a different structure, although they both have the same molecular formula. One is called normal butane, abbreviated to -butane the other may be called isobutane or 2-methylpropane - the latter name describes the structure of the compound, as you will see later. These compounds are isomers of one another. They are not the same compounds and have different melting points, boiling points and solubilities. Isomers are compounds which have the same moiecuiar formuia, but different moiecuiar structures. After butane, the longer the carbon chain of an alkane, the more structurai isomers are possible for a particular molecular formula. For example, there are 75 decanes (C10H22) and over three-hundred-thousand eicosanes (C20H42) ... 

Structural (or constitutional) isomers are compounds with the same molecular formulas but different structural formulas (that is, different arrangements of the atoms in the molecule). Isomerism is especially important in organic chemistry because of the capacity of carbon atoms to be arranged in so many different ways continuous chains, branched chains, and rings. Structural formulas can be written so that every bond is shown, or in various abbreviated forms. For example, the formula for n-pentane (n stands for normal) can be written as ... 

In the 0X0 industry, the term iso denotes a mixture of isomers and does not refer to the lUPAC definition. Therefore, the abbreviations included in Table 28.2 indicate when a phthalate ester is a mixture of branched or linear isomers (i.e., DNP for linear di-w-nonylphthalate, and DINP for branched diisononylphthalate). With the exception of di-(2-ethyUiexyl) phthalate, higher molecular weight phthalate esters (alkyl chains > 6 carbons) are mixtures based on the alcohols used for its production. Eor example, DINP is a mixture of di-C8-C10 branched alkylesters, containing principally isomers with nine carbon alkyl chains. In the same way, the term DIDP refers to a mixture of di-C9-ll branched alkyl esters (Cl0-rich) of phthalic acid. 

Notice how the propyl part of isopropyl still indicates three carbon atoms they are just joined together in a different way—in other words, as an isomer of the straight chain propyl group. Sometimes, to avoid confusion, the straight chain alkyl groups are called -alkyl (for example, -Pr, -Bu)—n for normal —to distinguish them from their branched counterparts. Iproniazid is an antidepressant drug with i-Pr in both structure and name. Isopropyl may be abbreviated to i-Pr, Pr, or Pr. We shall use the first in this book, but you may see the others used elsewhere. 

---