Introduction to Organic Chemistry Copyright The McGraw-ill Companies, Inc. Permission required for reproduction or display. 1
Common Elements in Organic Compounds 2
Classification of ydrocarbons ydrocarbons are made up of only hydrogen and carbon. 3
Alkanes Alkanes have the general formula C n 2n+2 where n = 1,2,3, only single covalent bonds saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms in the molecule C 4 C 2 6 C 3 8 methane ethane propane 4
Structural isomers are molecules that have the same molecular formula but different structures 5
ow many structural isomers does pentane, C 5 12, have? C C C C C n-pentane C 3 C C C C 3 C 3 C C C C 2,2-dimethylpropane 2-methylbutane 6
Physical Properties of Some Alkanes 7
Alkane Nomenclature 1. The parent name of the hydrocarbon is that given to the longest continuous chain of carbon atoms in the molecule. C 3 C 3 C 2 C 2 C C 2 C 2 C 3 1 2 3 4 5 6 7 4-methylheptane heptane 2. An alkane less one hydrogen atom is an alkyl group. C 4 methane C 3 methyl 8
Alkane Nomenclature 3. When one or more hydrogen atoms are replaced by other groups, the name of the compound must indicate the locations of carbon atoms where replacements are made. Number in the direction that gives the smaller numbers for the locations of the branches. C 3 C 3 C C 2 C 2 C 3 1 2 3 4 5 2-methylpentane C 3 C 3 C 2 C 2 C C 3 1 2 3 4 5 4-methylpentane 9
Alkane Nomenclature 4. Use prefixes di-, tri-, tetra-, when there is more than one alkyl branch of the same kind. C 3 C 3 C 3 C C C 2 C 2 C 3 1 2 3 4 5 6 2,3-dimethylhexane C 3 C 3 C C C 2 C 2 C 3 1 2 3 4 5 6 C 3 3,3-dimethylhexane 10
Alkane Nomenclature 5. Use previous rules for other types of substituents. Br NO 2 C 3 C C C 3 1 2 3 4 2-bromo-3-nitrobutane Cl F C 2 C 2 C C 3 1 2 3 4 1-chloro-3-fluorobutane 11
What is the IUPAC name of the following compound? C 3 C 2 5 C 3 C C 2 C C 2 C 2 C 2 C 3 1 2 3 4 5 6 7 8 2-methyl-4-ethyloctane What is the structure of 4-ethyl-2-methylhexane? C 3 C 2 5 C 3 C C 2 C C 2 C 3 1 2 3 4 5 6 12
Combustion C 4 (g) + 2O 2 (g) alogenation C 4 (g) + Cl 2 (g) light Alkane Reactions CO 2 (g) + 2 2 O (l) Δ 0 = -890.4 kj/mol C 3 Cl (g) + Cl (g) Cl 2 + energy Cl + C Cl + Cl C + Cl C + Cl Cl C Cl + Cl 13
Cycloalkanes Alkanes whose carbon atoms are joined in rings are called cycloalkanes. They have the general formula C n 2n where n = 3,4, 14
Geometry of Cycloalkanes more stable 15
Alkenes Alkenes have the general formula C n 2n where n = 2,3, contain at least one carbon-carbon double bond also called olefins C 2 C C 2 C 3 1-butene C 3 C C C 3 2-butene Cl Cl Cl C C C C Cl cis-dichloroethylene trans-dichloroethylene 16
Cis-Trans Isomerization in the Vision Process electron micrograph of retinal rods 17
Cracking Alkene Reactions C 2 6 (g) C 2 C 2 (g) + 2 (g) Pt catalyst Addition Reactions C 2 C 2 (g) + Br (g) C 3 C 2 Br (g) C 2 C 2 (g) + Br 2 (g) C 2 Br C 2 Br (g) 18
and/or Markovnikov s rule: in the addition of unsymmetrical (that is, polar) reagents to alkenes, the positive portion of the reagent (usually hydrogen) adds to the carbon atom that already has the most hydrogen atoms. 19
Alkynes Alkynes have the general formula C n 2n-2 where n = 2,3,4, contain at least one carbon-carbon triple bond C C C 2 C 3 C 3 C C C 3 1-butyne 2-butyne Production of acetylene CaC 2 (s) + 2 2 O (l) C 2 2 (g) + Ca(O) 2 (aq) 20
Alkyne Reactions ydrogenation C C (g) + 2 (g) C 2 C 2 (g) Addition Reactions C C (g) + Br (g) C 2 CBr (g) C C (g) + Br 2 (g) CBr CBr (g) C C (g) + 2Br 2 (g) CBr 2 CBr 2 (g) 21
Aromatic ydrocarbons C C C C C C C C C C C C Electron micrograph of benzene 22
Delocalized molecular orbitals are not confined between two adjacent bonding atoms, but actually extend over three or more atoms. Example: Benzene, C 6 6 Delocalized π orbitals 23
Other Representations of Benzene 24
Aromatic Compound Nomenclature ethylbenzene aminobenzene C 2 C 3 Cl N 2 NO 2 chlorobenzene nitrobenzene 6 1 2 Br Br Br 5 4 3 1,2-dibromobenzene Br 1,3-dibromobenzene 25
Substitution reaction Aromatic Compound Reactions Br + Br 2 FeBr 3 catalyst + Br C 2 C 3 + C 3 C 2 Cl AlCl 3 catalyst + Cl 26
Polycyclic Aromatic ydrocarbons 27
Functional Group Chemistry Alcohols contain the hydroxyl functional group and have the general formula R O. 28
Biological production of ethanol C 6 12 O 6 (aq) enzyme 2C 3 C 2 O (aq) + 2CO 2 (g) Commercial production of ethanol C 2 C 2 (g) + 2 O (g) 2 SO 4 C 3 C 2 O (g) Metabolic oxidation of ethanol alcohol dehydrogenase C 3 C 2 O C 3 CO + 2 29
Functional Group Chemistry Ethers have the general formula R O R. Condensation Reaction C 3 O + OC 3 2 SO 4 catalyst C 3 OC 3 + 2 O 30
Functional Group Chemistry Aldehydes and ketones contain the carbonyl ( C ) functional group. O O aldehydes have the general formula R C O ketones have the general formula R C R O O O C C C 3 3 C C C 3 formaldehyde acetaldehyde acetone 31
Functional Group Chemistry Carboxylic acids contain the carboxyl ( COO ) functional group. 32
Properties and Reactions of Carboxylic Acids Generally weak acids React with alcohols to form esters Neutralization Production of acid halides (intermediates in syntheses) 33
Functional Group Chemistry Esters have the general formula R COOR, where R is a hydrocarbon group. Characteristic odors and flavors ydrolysis Alkaline hydrolysis (saponification) 34
Functional Group Chemistry Amines are organic bases with the general formula R 3 N. C 3 N 2 + 2 O RN 3 + + O - Neutralization C 3 C 2 N 2 + Cl C 3 C 2 N 3+ Cl - 35
Chirality Enantiomers are nonsuperimposable mirror images. chiral achiral 36