Lesson 65 - Organic Chemistry I

synthetic fibres plastics artificial sweeteners drugs coal, petroleum

Organic Chemistry originally meant chemistry of “organisms” now means chemistry of C - containing compounds (but not CO2, H2CO3, etc.)

organic compounds once thought to have a “life force” until 1828... Organic Chemistry organic compounds once thought to have a “life force” until 1828... NH4OCN ® H2N - C - NH2 = O D ammonium cyanate urea (inorganic) (organic)

What’s so special about C? Organic Chemistry What’s so special about C?

Organic Chemistry What’s so special about C? - it bonds to itself ® long chains ® ring structures - it bonds to H, N, O, S, halogens, etc.

C : living things as Si : rocks Organic Chemistry C : living things as Si : rocks

» 107 compounds known so far » 90% of them are organic Organic Compounds » 107 compounds known so far » 90% of them are organic

most other organic compounds are derivatives of hydrocarbons made only of C, H most other organic compounds are derivatives of hydrocarbons

Hydrocarbons Methane, CH4

(each C is bound to 4 other atoms) Alkanes general formula CnH2n+2 alkanes are saturated (each C is bound to 4 other atoms)

Alkanes: Saturated Hydrocarbons C = C + H2(g) ® H - C - C - H(g) H H(g) H H Unsaturated Saturated (Ethane)

saturated vs. unsaturated fatty acids =O OH =O OH

Alkanes: Saturated Hydrocarbons CH4 methane natural gas C2H6 ethane making ethylene C3H8 propane heating, barbecues C4H10 butane lighter fluid C5H12 pentane solvent C6H14 hexane part of gasoline then heptane, octane, nonane, decane

Isomers methane 1 isomer ethane 1 isomer propane 1 isomer

Isomers normal butane (n-butane) isobutane

Drawing Structures n-butane CH3CH2CH2CH3 isobutane CH3CHCH3CH3 single bonds isobutane CH3CHCH3CH3

Draw all the isomers of pentane (C5H12) Drawing Structures Draw all the isomers of pentane (C5H12) 1. CH3 - CH2 - CH2 - CH2 - CH3 (n-pentane)

1. CH3 - CH2 - CH2 - CH2 - CH3 (n-pentane) CH3 2. CH3 - CH - CH2 - CH3 (isopentane)

CH3 2. CH3 - CH - CH2 - CH3 (isopentane) CH3 3. CH3 - C - CH3 CH3 (neopentane)

Equivalent Structures

a systematic naming system e.g. Nomenclature a systematic naming system e.g. CH3 - CH2 - CH - CH2 - CH3 CH2 CH3

Nomenclature CH3 6 carbons CH2 CH3 - CH2 - CH - CH2 - CH3 1. Find the longest continuous chain of carbon atoms; this is a hexane 2. Alkane groups as substituents are named as follows:

- CH3 methyl - CH2CH3 ethyl - CH2CH2CH3 propyl CH3CHCH3 isopropyl Alkyl Groups - CH3 methyl - CH2CH3 ethyl - CH2CH2CH3 propyl CH3CHCH3 isopropyl

- CH2CH2CH2CH3 butyl CH3CHCH2CH3 sec-butyl - CH2 - C - CH3 iso-butyl - C - CH3 tert-butyl H CH3 CH3 CH3

3. Number the long chain so that the 6 5 CH2 CH2 4 CH3 - CH2 - CH - CH2 - CH3 3 2 1 ethyl hexane 3. Number the long chain so that the substituents are at the lowest numbers 3-ethylhexane

other examples 2- methyl pentane 2,4- dimethyl pentane 1 3 5 2,4- dimethyl pentane 1 2 3 4 5 2,2,4-trimethylpentane (isooctane, octane rating = 100) 2 4 1 3 5

other examples 4-ethyl-3,5-dimethylnonane 4 1 9

other examples 4-tert-butylheptane

Cycloalkanes = cyclopropane

Cycloalkanes cyclobutane cyclopentane cyclohexane