CHE 332 Chapter Notes - Chapter 13: Conjugated System, Allyl Group, Molar Attenuation Coefficient
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Ch2=c=ch2): the(cid:455)"re less sta(cid:271)le tha(cid:374) isolated double bonds, middle carbon is sp hybridized, the(cid:455)"re (cid:373)ore rare, conjugated means they alternate double and single bonds, there"s delo(cid:272)alizatio(cid:374) which makes for more unusual double and single bonds. Isolated (cid:373)ea(cid:374)s there"s 1 or more saturated carbon atoms between the double bonds: double bonds at a distance work like regular double bonds do. Beer"s law: (cid:373)olar a(cid:271)sorpti(cid:448)it(cid:455) (cid:894) (cid:895), relati(cid:374)g a(cid:271)sor(cid:271)a(cid:374)(cid:272)e (cid:894)a(cid:895), (cid:272)o(cid:374)(cid:272)e(cid:374)tratio(cid:374) (cid:894)(cid:272)(cid:895), a(cid:374)d path le(cid:374)gth (cid:894)l(cid:895) Max: this makes them visible, uv vis spectroscopy can be used in the structure elucidation of organic molecules to indicate whether conjugation is present in a given sample. But since both the 1,4- and the 1,2-products readily form from the allylic cation at high temperature, eventually this equilibrium leads to a preponderance of the 1,4- product because it is more stable: dimerization. Intramolecular reactions also possible: the diene can act as a dienophile and just react with itself.
