Organic Chemistry-1

Organic Chemistry is the study of carbon-containing compounds and their properties.

Compounds are broken down into 2 general categories: Inorganic Compounds: Do not contain carbon

Timberlake LecturePLUS Organic Compounds Contain significant amounts of carbon. are mostly composed of 4 elements: H, O, N, C “honk” Have covalent bonds Have low melting points Have low boiling points Burn in air (oxygen) Are soluble in nonpolar solvents Form large molecules Timberlake LecturePLUS

Exceptions: oxides of carbon (CO2, CO) carbonates,bicarbonates(NaHCO3,CaCO3) cyanides (NaCN, etc)

Origin of organic compounds 21/10/99 Origin of organic compounds Naturally occurring organic compounds are found in plants, animals, and fossil fuels Synthetic organic compounds are derived from fossil fuels or plant material

Carbon: Carbon is essential to life for several reasons: It can form strong stable covalent bonds It can form up to 4 chemical bonds It can form multiple bonds

Hydrocarbons: Contain C and H only

21/10/99 1.Hydrocarbons Alkanes C C Alkenes C C Alkynes C C Aromatics

1.1.1. Alkanes Hydrocarbon chains where all the bonds between carbons are SINGLE bonds Have 4 bonds to every carbon (C)atom Are nonpolar molecules Saturated General formula: [CnH2n+2], where n is the number of C atoms in the compound. Name uses the ending –ane

Nomenclature International Union of Pure and Applied Chemistry colloquially: “eye-you-pac” Devised following WWII ca. 1946-1950

Timberlake LecturePLUS IUPAC Names Name # carbons condensed formulas Methane 1 CH4 Ethane 2 C2H6 Propane 3 C3H8 Butane 4 C4H10 Pentane 5 C5H12 Hexane 6 C6H14 The names of organic compounds are determined by the IUPAC rules (International Union of Pure and Applied Chemistry). The stem of the name states the number of carbon atoms in the carbon chain of the compounds. The suffix, in this case –ane, indicates the alkane family. Timberlake LecturePLUS

Timberlake LecturePLUS Structural Formulas H H   H C  H H C H H H CH4 , methane Each pair of electrons is shown as a line in the structural formula. In methane, CH4 the four valence electrons of carbon are shared with the single electrons of four hydrogen (H) atoms. Each pair of electrons is a single bond, which can be drawn as a line. When a structure is drawn to show each bond, it is called a complete structural formula. Timberlake LecturePLUS

Timberlake LecturePLUS More Alkanes Condensed Structural Formulas Ethane H C C H CH3 CH3 H H H Propane CH3 CH2 CH3 H H H H The complete structural formula for ethane shows the single bonds between two carbon atoms and six H atoms. The complete structural formula of propane shows the 3-carbon chain with single bonds to the attached H atoms. To write a condensed structural formula, the H atoms are written as a group next to their respective C atoms. H C C C H H H H Timberlake LecturePLUS

1.1.1.a. Alkyl Groups Alkyl group s are obtained when one H is removed from an alkane

Timberlake LecturePLUS 1999 Alkyl Groups H H C CH3 methyl H H H C C CH3CH2 ethyl An alkyl group is composed of one or more carbon atoms attached to a carbon chain. An alkyl group is derived from an alkane by removing one hydrogen. The ending –ane of the alkane is changed to –yl. The carbon branch from methane is the methyl group. The carbon branch from ethane is the ethyl group. Timberlake LecturePLUS 1999

CH3Cl methyl chloride CH2CH3Br ethyl bromide Shown as R- in general Name: replace -ane ending of alkane with -yl ending CH3 is “methyl” (from methane) CH2CH3 is “ethyl” (from ethane) CH2CH2CH3 is “propyl” (from propane) CH3Cl methyl chloride CH2CH3Br ethyl bromide

1.1.2. Cycloalkanes Cycloalkanes are alkanes having carbon atoms that form a ring. The two ends of the carbon chain are attached in a ring in a cyclic hydrocarbon General formula: CnH2n

 Structure is shown as a regular polygon with the number of vertexes equal to the number of C’s. H2C CH2 or cyclobutane C4H8

Cyclohexane or

to name, prefix the name of the corresponding open-chain alkane with cyclo-. Cyclobutane C4H8 Cyclopropane C3H6 Cyclohexane C6H12 Cyclopentane C5H10

1.1.3.Alkenes: hydrocarbons that contain a carbon-carbon double bond. the simplest member is ethene (ethylene).

No. of Carbon Atoms in One Molecule Structure of One Molecule Alkene Member Structure of One Molecule 2 ethene (C2H4) 3 propene (C3H6) 4 butene (C4H8) H C H C H C

General formula: [CnH2n], where n is the number of C atoms in the compound. names of alkenes end with –ene.

1.1.4. alkynes: Acetylene, the simplest alkyne. hydrocarbons containing a carbon-carbon triple bond. Acetylene, the simplest alkyne. “-yne” as a suffix indicates an alkyne General formula is CnH2n-2.

propyne (methylacetylene) Alkynes: CnH2n-2 C2H2 H—C  C—H ethyne (acetylene) C3H4 CH3CCH propyne (methylacetylene)

1.2.Aromatic hydrocarbons: A special class of cyclic unsaturated hydrocarbons. Called as “aromatic hydrocarbons”, because of pleasant odor Also called as arenes.

simplest aromatic is benzene (C6H6) or Benzene is a six-carbon ring, with alternating double and single bonds

One derivative of Benzene is called phenylethene, or commonly named STYRENE. Foamed styrene is trademarked by Dow Chemicals as “styrofoam” Other manufacturers usually just called “foam cups” CH2 CH

THE END!!! Don’t forget checking out “ Organic Chemistry- 2.”