Chemistry 2100 Lecture 2 Alkynes and Alkenes alkene

Chemistry 2100 Lecture 2

Alkynes and Alkenes alkene (olefins): Cn. H 2 n alkyne (acetylenes): Cn. H 2 n-2 Ethene Ethylene Acetylene

Naming Alkenes and Alkynes • Parent name is that of the longest chain that contains the C=C or C≡C. • Number the chain from the end that gives the lower numbers to the carbons of the C=C or C≡C. • Locate the C=C or C≡C by the number of its first carbon. • Use -ene to show C=C, -yne for C≡C. • For cycloalkenes: – Number ring carbons to give carbon 1 and 2 to the C=C bond. – Because of this convention, no need to specify the number of the C=C.

Alkene Isomerism 3 -methyl-trans-2 -pentene 2 -methyl-2 -pentene 3 -methyl-cis-2 -pentene

Conjugation

2

trans-retinal

trans-retinal

trans-retinal

trans-retinal 11 -cis-retinal

opsin

opsin

opsin

opsin rhodopsin

rhodopsin metarhodopsin

rhodopsin metarhodopsin

rhodopsin metarhodopsin

rhodopsin neural impulse metarhodopsin

neural impulse metarhodopsin 11 -cis-retinal trans-retinal

neural impulse metarhodopsin 11 -cis-retinal trans-retinal

neural impulse metarhodopsin 11 -cis-retinal trans-retinal

neural impulse metarhodopsin 11 -cis-retinal trans-retinal opsin

neural impulse metarhodopsin 11 -cis-retinal trans-retinal opsin

Terpenes – natural polyenes myrcene (bay) zingiberene (ginger) geraniol (rose) limonene (orange, dill) -selinene (celery) menthol (mint) carvone (spearmint, dill) caryophyllene (cloves)

squalene

squalene ~25 steps lanosterol cholesterol

Making Alkenes tetra tri di mono

Reactions of Alkenes Hydrogenation (cis or trans)

Partially Hydrogenated Vegetable Oil • • "partially hydrogenated vegetable oil"

Halogenation CH 2 Cl 2 RT ∆ / h Cl 2 CH 2 Cl 2

Acid Addition CH 2 Cl 2 minor H 2 SO 4 major

Polymerization Z Z = = CH 3 Cl CN OH polypropylene PVC polyacrylonitrile polyvinylalcohol

Polymers & Health Bisphenol A = hard shell plastic Pthalate, plasticizer