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Explore the fundamentals of organic chemistry focusing on alkenes, alkynes, and hydrocarbons. Learn about the structure, nomenclature, isomerism, and reactions of these important compounds. This comprehensive guide by Prof. Dr. Adel M. Awadallah from the Islamic University of Gaza is essential for students in Chem 2311.
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Organic chemistry for medicine and biology students Chem 2311 Chapter 3 By Prof. Dr. Adel M. Awadallah Islamic University of Gaza
Alkenes and Alkynes Hydrocarbons(contain only carbon and hydrogen) • Saturated: (Contain only single bonds) Alkanes (CnH2n + 2 ) Cycloalkanes (CnH2n ) b)Unsaturated: contain Alkenes: double bonds (,,,CnH2n) Alkynes: triple bonds ((CnH2n - 2) Aromatic: benzene like compounds
Nomenclature of alkenes and Alkynes • The ending ene is used for alkenes and yne for alkynes • Select the longest chain that includes both carbons of the multiple bond • Number the chain from the end nearest to the multiple bond • Indicate the position of the multiple. Examples
Nomenclature of compounds containing more than one multiple bond • Number from the end nearest to the multiple bond. • If a double and a triple bond are equidistant from he end, the double bond receives the lowest numbers • Example
Cis-Trans (Z-E) Isomerism in Alkenes If each end of the double bond is attached to two different groups, then the compound exists in two different forms called (Diastereomers; These are non mirror image stereoisomers). If the two groups are identical we distinguish the two isomers by adding the prefix cis (same side) or trans (opposite sides) Example
If the groups attached to the double bond are different, we distinguish the two isomers by adding the prefix Z (same side) or E (opposite sides) depending on the atomic number of the atoms attached to each end of the double bond