Naming compounds alkenes

Hydrocarbons with one or more carbon-to-carbon double bonds are called alkenes. The names of alkenes end with -ene. Ethene, or ethylene, the simplest alkene, has two carbon atoms connected by a double bond. The double bond consists of two pairs of shared electrons, one pair from one carbon atom and one pair from the other carbon atom. Each of the carbons also has two single bonds with hydrogen atoms so that the formula for the compound can be written as... 

The rales of the IUPAC system for naming the alkenes are as follows 1. Select as the parent structure the longest continuous chain that contains the carbon-carbon double bond then consider the compound to have been derived from this structure by replacement of hydrogen atoms by various alkyl groups. 

Alkynes are named in a manner nearly identical to the naming of alkenes except that the suffix is -yne. The same rules for numbering apply. Compounds with several triple bonds use the suffixes -diyne, -triyne, and so on. For compounds that contain both a double bond and a triple bond, both suffixes are used, as in -enyne. Some examples follow ... 

Common Names Most alkenes are conveniently named by the IUPAC system, but common names are sometimes used for the simplest compounds. 

The names of alkenes follow the same format as the names of alkanes prefix + root + suffix. The prefixes and the steps for locating and identifying branches are the same, too. The greatest difference involves the double bond. The suffix -ene immediately tells you that a compound has at least one double bond. The rest of the necessary information—the location of the double bond, and the number of carbon atoms in the main chain—is communicated in the root. Follow the steps below to find out how to name the compound in Figure 13.20. 

The names of alkenes are obtained by simply changing the -ane of the alkane with the same number of carbon atoms to -ene . So, all the compounds of this hydrocarbon series have names ending in -ene. 

The suffix a can be added to the stem of the substituent (giving stanna) and used to indicate replacement of carbon. This is most useful with cyclic compounds, thus cyclo-(CH2)5SnMe2 is 1,1-dimethylstannacyclohexane. Doubly bonded compounds are similarly named as alkenes with one or two of the doubly-bonded atoms replaced by tin the compound R2Sn=CR2 is a stannene, and iUSrwSnfU is a distannene. 

The names of alkenes are based on the longest continuous chain of carbon atoms that contains the double bond. The chain is named by changing the ending of the name of the corresponding alkane from -ane to -ene. The compound on the left in Figure 24.7, for example, has a double bond as part of a three-carbon chain thus, the parent alkene is propene. 

To name an alkene containing two or more double bonds, we change the infix to -adien-, -atrien-, and so forth. Compounds containing several double bonds are called polyenes. 

As these two examples demonstrate, the names of alkanes end with -ene and nnmbers are nsed to indicate the position of the double bond. The parent chain is nnmbered so that the lowest nnmber possible is given to one of the carbon atoms in the donble bond, regardless of any other substitnents present in the compound (for example, alkyl gronps or halides). The numbers in the names of alkenes refer to the lowest numbered carbon atom in the chain that is part of the C=C bond of the alkene. The name butene means that there are four carbon atoms in the longest chain. Because of restricted rotation abont the carbon-carbon double bond, alkenes can form geometric isomers (Section 4.4). In this case, the name of an alkene must also specify whether the isomer is cis or trans ... 

Since Theodor Curtius reported the synthesis of ethyl diazoacetate in 1883, Buchner had investigated its reactions with carbonyl compounds, alkenes, alkynes, and aromatic compounds for more than 30 years.His extensive contributions in this area resulted in two reactions named in his honor the Buchner-Curtius-Schlotterbeck reaction (formation of ketones from aldehydes and aliphatic diazo compounds) and the Buchner reaction. The prototypical example of the latter involves the thermal or photochemical reaction of ethyl diazoacetate with benzene to give (via norcaradiene 7) a mixture of four isomeric cycloheptatrienes 8-11. Initially, Buchner believed that a single norcaradiene product 7 was generated from this reaction, but later, he realized that the hydrolysis of the product afforded a mixture of four isomeric carboxylix acids. The norcaradiene formulation persisted until 1956 when Doering reinvestigated this reaction. ... 

The synthesis of 4-vinylindoles has also been accomplished using an enyne metathesis approach. Using the same ideas as those shown in Scheme 17.18, Yoshida and Yanagisawa were able to easily synthesize a range of the precursor pyrroles containing an acetylene and alkene functionality on adjacent carbons, namely, compound 207 [68], When 207 was subjected to the 2-Ru catalyst under an atmosphere of ethylene gas, the intermediate 208 was formed. When treated with TsOH, the benzene ring of the 4-vinylindole 209 was subsequently formed in an excellent yield of 99% (Scheme 17.42). Other examples of this useful approach are illustrated in this paper [68],... 

The lUPAC system for naming organic compounds extends to the naming of alkenes by stipulating how to indicate the position of the double bond in the chain. The basic names of the alkenes are assembled as for the alkanes, except that the names end in -ene rather than -ane. A fifth step needs to be added to those we identified before so that we can indicate the position in the chain of the C=C double bond ... 

The lUPAC names of alkenes use the suffix -ene. Alkynes, which are also unsaturated because they contain one or more carbon-carbon triple bonds, will be discussed in Chapter 7. Unsaturated compounds that contain a benzene ring or structural units that resemble a benzene ring are aromatic hydrocarbons. They will be discussed in Chapter 13. 

The general syntheses of alkenes (p. 28 — 44) and 1,2-dihydroxy compounds (p. 50—54 and 123 — 132) are not repeated here. But there is an important chiral pool" for chiral 1,2-disubstituted compounds, namely a-amino acids. 

The acylpalladium complex formed from acyl halides undergoes intramolecular alkene insertion. 2,5-Hexadienoyl chloride (894) is converted into phenol in its attempted Rosenmund reduction[759]. The reaction is explained by the oxidative addition, intramolecular alkene insertion to generate 895, and / -elimination. Chloroformate will be a useful compound for the preparation of a, /3-unsaturated esters if its oxidative addition and alkene insertion are possible. An intramolecular version is known, namely homoallylic chloroformates are converted into a-methylene-7-butyrolactones in moderate yields[760]. As another example, the homoallylic chloroformamide 896 is converted into the q-methylene- -butyrolactams 897 and 898[761]. An intermolecular version of alkene insertion into acyl chlorides is known only with bridgehead acid chlorides. Adamantanecarbonyl chloride (899) reacts with acrylonitrile to give the unsaturated ketone 900[762],... 

The term gaz olefiantwas the forerunner of the gen eral term olefin formerly used as the name of the class of compounds we now call alkenes... 

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

A newer method for the preparation of nitronic esters, namely utilizing the (9-trimethyl-silyl ester, has been reported and these are prepared by the reaction of alkylnitro compounds and (V,(V-bis(trimethylsilyl)acetamide. These nitronic esters also undergo cycloaddition with alkenes to produce isoxazolidines (equation 54) (74MIP41601, 74DOK109, 78ACS(B)ll8). 

Alkenes and alkynes are similar in structure to the alkanes except the alkenes contain a carbon-to-carbon double bond (C=C) and the alkynes contain a carbon-to-carbon triple bond (C=C). The name prefixes are exactly the same as for the alkanes with the same number of carbons, but the endings are -one for compounds with double bonds and their derivatives and -yne for compounds with triple bonds... 

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