Double bonds constitutional isomers containing

The four constitutional isomers of cis and tram-1,2-dimet hy I eye lopn tpane that do not contain double bonds are... 

Lumefantrine contains two stereogenic units, i.e., a Z-configured double bond and a chirality centre whose configuration in the formula given is unspecified. As a result the formula represents two compounds (enantiomers) with R,Z and S,Z configuration, respectively. Both are present in the racemic pharmaceutical. There are formally 22 = 4 isomers possible with this constitution in addition to the isomers of lumefantrine there are also two others with an E-configured double bond. 

A limited number of chiral compounds having no stereogenic centers exist. For example, although A is achiral, constitutional isomer B is chiral. Make models and explain this observation. Compounds containing two double bonds that share a single carbon atom are called allenes. 

Many aldehydes and ketones may exist in an equilibrium mixture of two constitutional or structural isomers called tautomers. Tautomers differ from one another in the placement of a hydrogen atom and a double bond. One tautomer is the keto form (on the left in the equation below). The keto form has the structure typical of an aldehyde or ketone. The other form is called the enol form (on the right in the equation below). The enol form has a structure containing a carbon-carbon double bond (cm) and a hydroxyl group, the fimctional group characteristic of alcohols (ol). 

Problem 2.9 Polymers of dienes (hydrocarbons containing two carbon-carbon double bonds), such as butadiene and isoprene, have the potential for head-to-tail and head-to-head isomerism and variations in double-bond position as well. How many constitutional isomers can form in the polymerization of (a) polybutadiene and (b) polyisoprene ... 

Exercise Use MOLGEN-ONLiNE at http //www.molgen.de to evaluate the number of constitutional isomers of formula C4H4 that do not contain any triple bonds. Do the same for the number of isomers that contain neither triple nor double bonds. 

On examining the structures of acetone and propylene oxide several key aspects are clearly different (Fig. 1.2). Acetone contains a double bond between the oxygen atom and the central carbon atom. Propylene oxide does not contain a double bond, but has three atoms joined in a ring. The connectivity of the atoms is clearly different in acetone and propylene oxide. Their structures have the same molecular formula but a different constitution. We call such compounds constitutional isomers. ... 

Write the bond-line formula for a constitutional isomer of the compound shown below that does not contain a double bond. 

In summary, there are three constitutional isomers of C4H8 that contain a double bond ... 

The molecular formula 04 indicates an HDI of 1. As such, every constitutional isomer of C4H8 must contain either one ring or one double bond. The following structures are consistent with this description. Each of the first three constitutional isomers (shown here) exhibits a double bond, while each of the last two constitutional isomers exhibits a ring. 

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