Chain with conjugated multiple bonds

The formation of rings in the pdymer chain by the pdymerization of nitrile groups has also been observed in the bulk pd3rmerization of acrylonitrile by Trifonov and Shopov. In this study of the electroinitiated pdymerization of acrylonitrile with tetraethylammonium perchlorate as supporting electrolyte, the polymer was formed on a germanium prism which was part of an internal reflection spectroscopy device. The appearance of the absorption band at 1570 cm" in the spectrum of Ae yellow colored polymer indicated the presence of conjugated multiple bonds idiich was also supported by uv absorption at a lot r wavelength 304 tun, compared to 271 nm for white polyacrylonitrile prepared by free-radical initiation. 

This is, however, not the case, if conjugation exists between multiple bonds in the side chain and those in the aromatic nucleus, compare the R.E. of styrene and phenylacetylene with that of benzene. We shall return to this in the discussion of the conjugation in open chains. 

A more difficult problem is encountered when it is necessary to reduce selectively multiple bonds in the side chain, especially when they are conjugated with the nucleus. Up to the present time little has been published on this subject. The best method for the side chain reduction of /3-2-furylacrylic acid seems to be with Raney alloy in dilute NaOH. If the reaction is carried out more drastically, the nucleus undergoes easy reduction to give 4-hydroxy-valerolactone. The method of Railings and Smith also appears to be successful this involves the use of palladium strontium carbonate for the reduction of the alkene side chain of 2 -furylalkenes, without affecting the ring. Such compounds as j8-2 -furylacrylic esters are exceptions, but the potassium salt of the acid can be selectively reduced in aqueous solution. 

Alkadienes, alkatrienes, and alkatetraenes (poly-enes). These are unsaturated aliphatic hydrocarbons containing two, three, or four C = C double bonds, respectively. Alkadienes are also called diolefins or dienes, and alkatrienes are also known as triolefins or tricncs. Alkenes containing multiple double bonds fall under the general class of poly-enes. Double bonds that alternate with single bonds in a straight chain are said to be conjugated. Examples are... 

Diynes and triynes refer to alkynes containing two or three triple bonds poly-ynes contain multiple triple bonds. A conjugated triyne is a straight-chain hydrocarbon with triple bonds alternating with single bonds. An examples is... 

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