Organic Chemistry Introduction

Organic Chemistry Historically: The chemistry of compounds that come from living things Today: The chemistry of the compounds of carbon (except a few simple carbon compounds such as CO 2, Na 2 CO 3, KCN…)

Organic molecules present an enormous diversity in size, shape, complexity, properties, and reactions. Why? C atom can be covalently bonded to other C atoms and to atoms of other elements in a wide variety of ways. Organic Chemistry

InorganicOrganic 1.High melting points Low melting points 2.High boiling points Low boiling points 3.High solubility in water; low solubility in nonpolar solvents Low solubility in water; high solubility in nonpolar solvents 4.Nonflammable Flammable

InorganicOrganic 5.Solutions are conductors of electricity Solutions are nonconductors of electricity 6.Chemical reactions are rapid Chemical reactions are usually slow 7.Isomers are limited to a few exceptions (e.g., the transition elements) Exhibit isomerism 8.Exhibit ionic bonding Exhibit covalent bonding 9.Compounds contain relatively few atoms Compounds contain many atoms

Number of inorganic compounds: over Number of organic compounds: over Unique features of Carbon:  Having a covalency of four  The bonds are equivalent  Ability to form multiple bonds

BondBond enthalpy  H°/kJ mol-1 Bond distance nm C C C

 Ability to catenate form chainsform rings of identical atoms

EE lectronegativity: 2.5 (ability to combine with other elements to form predominantly covalent bonds)

Hetero atoms Elements of carbon compounds H O N S F Cl Br I

Hybridization sp 3 hybridization: C: [He]2s 2 2p x 1 2p y 1 4 hybridorbitals with 1 electron each: 4  bonds Geometry: tetrahedral Bond angle: 109 o 28’

Hybridization sp 2 hybridization: C: [He]2s 2 2p x 1 2p y 1 3 hybridorbitals with 1 electron each: 3  bonds 1 atomorbital with 1 electron: 1  bond Geometry: trigonal Bond angle: 120 o

Hybridization sp hybridization: C: [He]2s 2 2p x 1 2p y 1 2 hybridorbitals with 1 electron each: 2  bonds 2 atomorbitals with 1 electron each: 2  bonds Geometry: linear Bond angle: 180 o