Homologous series alkynes

Alkynes are similar to both alkanes and alkenes because they form a homologous series. Alkynes have the general formula of CnH2n-2- So, for example, the first member of the alkyne series, ethyne, has the formula C2H2. (You may know this compound by its common name acetylene.) The next member, propyne, has the formula C3H4. 

Solubility-Molar Volume Relationships The correlation between aqueous solubility at room temperature and the molar volume has been studied by McAuliffe [5] for different hydrocarbon classes. He discusses linear relationships, presented as graphs, describing the decrease in solubility with increasing molar volume for the homologous series of alkanes, alkenes, alkandienes, alkynes, and cycloalkanes. 

Write the general formulas for the alkane, alkene, alkyne, and cycloalkane homologous series. 

Like the alkanes and alkenes, the alkynes form a homologous series, the increment again being — CH2—. 

Naming alkynes Straight-chain alkynes and branched-chain alkynes are named in the same way as aikenes. The only difference is that the name of the parent chain ends in -yne rather than -ene. Study the examples in Table 22-5. Alkynes with one triple covalent bond form a homologous series with the general formula C H2 2- What are the molecular formulas for... 

DOT Label Flammable Gas, UN 1001 Formula C2H2 MW 26.04 CAS [74-86-2] Structure HC=CH, first member of the alkyne homolog series Synonyms ethyne ethine... 

Alkynes The alkynes are a homologous series of hydrocarbons containing a triple bond. The triple bond is formed from one cr bond and two tt bonds. The bond is rigid and allows no rotation. Alkynes with one triple bond have the formula C H2 . The... 

The reactions of C H2/i+2N immonium ions generated by dissociative ionization of alkylamines have been reviewed recently, so only a brief sununary is presented. The principal reaction is loss of an alkene, CmUim, with formation of a smaller inuno-nium ion . Some lower members of the homologous series (n = 2-5) lose an alkyne, CmH2m-2, to give a piotonated alkylamine ", but this fragmentation is rapidly superseded by alkene elimination for larger C H2n+2N+ species. 

Acetylene, H—C=C—H, is the first member of a homologous series of hydrocarbons containing triple bonds. Aside from acetylene, these substances (called alkynes) have not found wide use, except for the manufacture of other chemicals. 

On the basis of the effects observed on product selectivity in the alkyne hydration reaction mediated by the encapsulated NHC-Au(I) catalyst within the hexamer of resorcin[4]arene, Scarso and coworkers investigated the ability of the same supramolecular catalytic system in the selection of homologous series of substrates [46],... 

Groups of compounds, such as the hydrocarbons called the alkanes (and each separately, the alkenes, the alkynes, and the arenes ) that have similar structures, frequently have similar chemical and physical properties. The members of such structurally related groups are said to constitute a homologous series and, given the properties of some of its members, it is frequently possible to estimate the properties of others. 

Both the alkenes and the alkynes make up a new homologous series. Just as with the alkanes, each series may be extended by adding —CH2— units. Longer chains may have more than one multiple bond, but we will not consider such compounds in this text (Fig. 21.8). The general formula for an alkene is Cnll2ji, and for an alkyne, Q 2n-2-... 

Acetylene (ethyne), HC=CH, is the first member of the ALKYNE homologous series, whose general formula is C H2 2. The ending -yne indicates the presence of the —C=C— bond. 

All hydrocarbons—alkanes, alkenes, and alkynes—have similar physical properties. They are all insoluble in water but soluble in nonpolar solvents (Section 3.9). They are less dense than water and, like other homologous series, have boiling points that increase with increasing molecular weight (Table 7.2). Alkynes are more linear than alkenes, and a triple bond is more polarizable than a double bond (Section 3.9). These two features cause an alkyne to have stronger van der Waals interactions and, therefore, a higher boiling point than an alkene with the same number of carbons. 

In his summary of the identified components of tobacco smoke, Kosak (2170) listed only one unequivocally identified alkene or alkyne. It was ethyne (acetylene). Johnstone and Plimmer (1971) listed the following alkenes and alkynes identified in tobacco smoke cis- and trans-huteae, 1,3-buta-diene, methyl-1,3-butadiene (isoprene), ethene, ethyne, meth-ylethyne, propene, methylpropene, squalene and isosqualene, and several phytadienes. Less than a decade later, Stedman (3797) described and/or discussed nearly 235 acyclic alkenes and alkynes identified in tobacco smoke. This number includes the cis and trans isomers in the homologous mono-alkene series discussed below. 

For alkenes (Table 3.3), alkynes, and arenes, the concept of homology as pertains to addition of alkyl substituents also continues to apply, although positional isomerism and stereochemistry play important roles. Addition of further carbon-carbon double bonds, triple bonds, and/or aryl groups, as well as branching, confounds widespread prediction however, in a closely related series, the principle is maintained. 

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