Organic Chemistry Lecture Notes PDF

Organic Chemistry 1-1  Organic Chemistry  The study of carbon compounds.  Over 10 million compounds have been identified.  About 1000 new ones are identified each day!  C is a small atom.  It forms single, double and triple bonds.  It is interm...

Organic Chemistry 1-1  Organic Chemistry  The study of carbon compounds.  Over 10 million compounds have been identified.  About 1000 new ones are identified each day!  C is a small atom.  It forms single, double and triple bonds.  It is intermediate in electronegativity (2.5).  It forms strong bonds with C, H, O, N, and some metals.  Organic compounds are everywhere around us—in our foods, flavors, and fragrances; in our medicines, toiletries, and cosmetics; in our plastics, films, fibers, and resins, in our paints and varnishes, in our glues and adhesives; in our fuels and lubricants, and of course in our bodies and those of all living things. 1-2  Functional Groups  Functional group: An atom or group of atoms within a molecule that shows a characteristic set of chemical reactivities.  Functional groups are important for three reasons; they are: 1. the units by which we divide organic compounds into classes. 2. the sites of characteristic chemical reactions. 3. the basis for naming organic compounds. 1-3  Hydrocarbons Aliphatic Aromatic Open chain Cyclic (Non-cyclic) Saturated Unsaturated Saturated Unsaturated (Alkanes) (Cycloalkenes) (Cycloalkanes) C C C C C C CH4 (Alkenes) (Alkynes) CH3 CH3 C C C C 3 SP hybridized CH2 CH2 HC CH SP3 hybridized SP2 hybridized SP2 hybridized SP hybridized - Alkanes are also called paraffins. - Alkenes are also called olefins. - Alkynes are also called acetylenes. 1-4 Classification of C  Primary (1°) C: A carbon bonded to one other carbon.  Secondary (2°) C: A carbon bonded to two other carbons.  Tertiary (3°) C: A carbon bonded to three other carbons.  Quaternary (4°) C: A carbon bonded to four other carbons. 1-5 Classification of C 1-6 Covalent bonding and shapes of molecules 1-7 s & p orbital shape 1-14  Hybridization of Atomic Orbitals  Linus Pauling proposed that atomic orbitals for each atom should be thought of as first combining to form new atomic orbitals, called hybrid orbitals, which then interact to form bonds by overlapping with orbitals from other atoms.  Hybrid orbitals are formed by combinations of atomic orbitals by a process called hybridization.  The number of hybrid orbitals formed is equal to the number of atomic orbitals combined.  Elements of the 2nd period (like carbon) form three types of hybrid orbitals, designated sp3, sp2, and sp. 1-15 sp3 hybridization  The combination of one 2s atomic orbital and three 2p atomic orbitals forms four equivalent sp3 hybrid orbitals. 4 orbitals of equal energy forming 4 sigma bonds 2p Energy sp3 2s sp 3 Hybridization, with electron population for carbon to form four single bonds 1-16 sp3 hybridization 1-17 sp3 hybridization Bonding and structure of tetrahedral methane (CH4) – an sp3 hybridized molecule. 1-18  sp2 Hybridization  The combination of one 2s atomic orbital and two 2p atomic orbital forms three equivalent sp2 hybrid orbitals. 3 orbitals of equal energy 3 sigma bonds 1 orbital of higher energy 1 pi bond 2p 2p Energy sp2 2s sp 2 Hybridization, with electron population for carbon to form double bonds 1-19 sp2 Hybridization 1-20 sp2 Hybridization Trigonal planar structure sp2 hybridized orbitals p orbitals 1-21  sp Hybridization  The combination of one 2s atomic orbital and one 2p atomic orbital gives two equivalent sp hybrid orbitals. 2 orbitals of equal energy 2 sigma bond 2 orbitals of higher energy 2 pi bond 2p 2p Energy sp 2s sp Hybridization, with electron population for carbon to form triple bonds 1-22 sp Hybridization Linear 1-23 Chemical Bonding sp hybridization sp hybridized orbitals p orbitals 1-24