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Introduction to Organic Chemistry. Chapter 11. Common Elements in Organic Compounds. 11.1. Classification of Hydrocarbons. 11.1. Alkanes. Alkanes have the general formula C n H 2 n +2 where n = 1,2,3,… only single covalent bonds
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Introduction to Organic Chemistry Chapter 11
Alkanes • Alkanes have the general formula CnH2n+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 CH4 C2H6 C3H8 methane ethane propane 11.2
Structural isomers are molecules that have the same molecular formula but different structures 11.2
H H H H H C C C C C H H H CH3 H H H H H H C C C H H H CH3 H H H H CH3 C C C C H H H H H H How many structural isomers does pentane, C5H12, have? n-pentane 2,2-dimethylpropane 2-methylbutane 11.2
CH3 CH2 CH2 CH CH2 CH2 CH3 CH3 Alkane Nomenclature • The parent name of the hydrocarbon is that given to the longest continuous chain of carbon atoms in the molecule. 4-methylheptane 1 2 3 4 5 6 7 • An alkane less one hydrogen atom is an alkyl group. methane CH4 CH3 methyl 11.2
Alkane Nomenclature 11.2
CH3 CH CH2 CH2 CH3 CH3 CH3 CH2 CH2 CH CH3 CH3 Alkane Nomenclature • 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. 1 2 3 4 5 2-methylpentane 1 2 3 4 5 4-methylpentane 11.2
CH3 CH3 CH CH CH2 CH2 CH3 CH3 1 2 3 4 5 6 CH3 CH C CH2 CH2 CH3 CH3 1 2 4 5 6 3 CH3 Alkane Nomenclature • Use prefixes di-, tri-, tetra-, when there is more than one alkyl branch of the same kind. 2,3-dimethylhexane 3,3-dimethylhexane 11.2
Br NO2 CH CH CH3 CH3 1 2 3 4 Br NO2 CH2 CH CH3 CH2 1 2 3 4 Alkane Nomenclature • Use previous rules for other types of substituents. 2-bromo-3-nitrobutane 1-bromo-3-nitrobutane 11.2
CH3 C2H5 CH CH2 CH CH2 CH2 CH2 CH3 CH3 What is the structure of 2-propyl-4-methylhexane? C2H5 CH3 CH CH2 CH CH2 CH3 CH3 1 2 3 4 5 6 What is the IUPAC name of the following compound? 1 2 3 4 5 6 7 8 2-methyl-4-ethyloctane 11.2
CH4(g) + 2O2(g) CO2(g) + 2H2O (l)DH0 = -890.4 kJ CH4(g) + Cl2(g) CH3Cl (g) + HCl (g) light Cl2 + energy Cl• + Cl• H H H H Cl• + H H C C H H Cl H C C • • H H H H + Cl Cl Alkane Reactions Combustion Halogenation + HCl + Cl• 11.2
achiral chiral 11.2
Cycloalkanes Alkanes whose carbon atoms are joined in rings are called cycloalkanes. They have the general formula CnH2n where n = 3,4,… 11.2
Cycloalkanes 11.2
CH CH CH3 CH3 CH CH2 CH3 CH2 Cl Cl H Cl C C C C H H Cl H Alkenes • Alkenes have the general formula CnH2n where n = 2,3,… • contain at least one carbon-carbon double bond • also called olefins 1-butene 2-butene cis-dichloroethylene trans-dichloroethylene 11.2
Pt C2H6(g) CH2 CH2(g) + H2(g) catalyst CH2 CH2(g) + HBr (g) CH3 CH2Br (g) CH2 CH2(g) + Br2(g) CH2Br CH2Br (g) Alkene Reactions Cracking Addition Reactions 11.2
CaC2(s) + 2H2O (l) C2H2(g) + Ca(OH)2(aq) C CH2 CH3 CH C C CH3 CH3 Alkynes • Alkynes have the general formula CnH2n-2 where n = 2,3,4,… • contain at least one carbon-carbon triple bond 1-butyne 2-butyne Production of acetylene 11.2
CH CH (g) + H2(g) CH2 CH2(g) CH CH (g) + HBr (g) CH2 CHBr (g) CH CH (g) + Br2(g) CHBr CHBr (g) CH CH (g) + 2Br2(g) CHBr2 CHBr2(g) Alkyne Reactions Hydrogenation Addition Reactions 11.2
H H C H H C H H C C C C C C C C H H C H H C H H Aromatic Hydrocarbons 11.3
ethylbenzene aminobenzene CH2CH3 Cl NH2 NO2 chlorobenzene nitrobenzene Br Br Br 1 6 2 Br 5 3 4 Aromatic Compound Nomenclature 1,2-dibromobenzene 1,3-dibromobenzene 11.3
CH2CH3 Br H H FeBr3 + Br2 + HBr H H H H H H H H catalyst H H H H H H H H H H H H AlCl3 + CH3CH2Cl + HCl catalyst Aromatic Compound Reactions Substitution reaction 11.3
Functional Group Chemistry Alcohols contain the hydroxyl functional group and have the general formula R-OH. 11.4
enzyme C6H12O6(aq) 2CH3CH2OH (aq) + 2CO2 (g) H2SO4 CH2 CH2(g) + H2O (g) CH3CH2OH (g) alcohol dehydrogenase CH3CH2OH CH3CHO + H2 Biological production of ethanol Commercial production of ethanol Metabolic oxidation of ethanol 11.4
H2SO4 CH3OH + HOCH3 CH3OCH3 + H2O catalyst Functional Group Chemistry Ethers have the general formula R-O-R’. Condensation Reaction 11.4
Aldehydes and ketones contain the carbonyl ( ) functional group. • aldehydes have the general formula C O O O O O O CH3 CH3 • ketones have the general formula H C H C H R C R’ R C H C H3C Functional Group Chemistry formaldehyde acetaldehyde acetone 11.4
Functional Group Chemistry Carboxylic acids contain the carboxyl ( -COOH ) functional group. 11.4
O CH3COOH + HOCH2CH3 CH3 C O CH2CH3 + H2O Functional Group Chemistry Esters have the general formula R’COOR, where R is a hydrocarbon group. ethyl acetate 11.4
CH3NH2 + H2O RNH3+ + OH- CH3CH2NH2 + HCl CH3CH2NH3+Cl- Functional Group Chemistry Amines are organic bases with the general formula R3N. 11.4