Tutorial #20 - Organic Chemistry 1. Nomenclature Find the longest chain of carbons Name the hydrocarbon, using –ane, -ene or –yne as required Identify any substituent groups on the chain Number the chain appropriately. e.g. CH3-CH2-CH2-CHCl-CH3 5 carbons, i.e. pent - something no double or triple bonds, thus pentane a chlorine on one of the C’s, thus chloropentane numbering from the right to obtain the lowest number, 2-chloropentane e.g. H2C H C CH3 Cl Cl a. 4 carbons, i.e. but – something b. a double bond, i.e. butene c. the double bond is on carbon number 1, thus 1-butene d. two chlorines on the C, thus dichlorobutene e. numbering from the left, 3,3-dichloro-1-butene e.g. CHC-CH2-C6H5, where the C6H5 is a phenyl group HC HC C H2 H C C H CH CH a. The ring does not enter into the longest "chain", and so this is a three carbon chain, i.e. prop - something. b. a triple bond, thus 1-propyne. c. a phenyl group, thus phenyl-1-propyne d. phenyl on the third carbon, thus 3-phenyl-1-propyne You could also name this as a benzene compound, i.e. propynyl benzene, where the propynyl indicates a propyne group as a substituent. Since the C in the propynyl group must the number 1 (since it is bound to the benzene), the correct name would be 2-propynyl benzene. e.g. CH3-CH2-CHOH-CH2-CH2-CH3 H2 H2 C H C CH3 H3C C C H2 OH a. an alcohol, 6 carbons, i.e. derived from hexane, thus hexanol 3. the OH group is on the third carbon, thus 3-hexanol, or hexan-3-ol e.g. CH3-CH2-CH2NH2 H3C H2 C C H2 NH2 a propane, i.e. 1-aminopropane, or an amine, i.e. propylamine e.g. CH3-CH2-CH2-CH2-COOH H3C H2 C C H2 H2 C O OH a carboxylic acid, 5 carbons, pentane carboxylic acid e.g. C6H5 – CH2 – COOH HO HC O H C CH2 HC CH C H a carboxylic acid, 2 carbons, phenylacetic acid e.g. H-CO-C3H7 O C H H2 C C H2 CH3 recognize the carbonyl group, CO, and the fact that the C in the CO group is a primary carbon, i.e. bound to only one other carbon. This must therefore be an aldehyde. It has four carbons, and is therefore derived from butane, butyl aldehyde e.g. CH3-CO-C2H5 O C H2 H3C CH3 recognize the carbonyl group, CO, and the fact that the C in the CO group is a secondary carbon, i.e. bound to two other carbons. This must therefore be a ketone, methyl ethyl ketone. e.g. CH3 – CO – O – C4H9 O H3C O H2 C C H2 H2 C CH3 This is an ester, (note the COO-C linkage), butyl methyl ester. Note that we name the group on the oxygen first (the butyl group in this case) Note also that this ester contains the very common H3C-COO group, commonly called the acetyl group. Since the acetyl group is in an ester, it is called an acetate, or butyl acetate in this case. e.g. NH2CH3 methyl amine or amino methane e.g. CH3 – CO – NH2 O H3C NH2 an amide, (note the C-O-N), ethanamide. Since this also contains the common acetyl group, acetamide is its more common name. CH3 – CO – NHCH3 an amide, (note the C-O-N), N-methyl acetamide, denoting the fact that the methyl group is on the N atom. Cl Cl dichlorobenzene. Since the chlorine atoms are on opposite carbons, paradichlorobenzene, or 1,4-dichlorobenzene. Cl NO2 Cl 2,5-dichloronitrobenzene (since we named it as a nitrobenzene, carbon number one is the one bound to the nitro group) OH O Cl parachlorobenzoic acid or 4-chlorobenzoic acid (since we named it as a benzoic acid, the COOH group is on carbon number 1) 2. Reactions Reactions you should know: Alkanes: Reaction with oxygen, chlorine, dehydrogenation Alkenes: addition reactions Alkynes: addition reactions Alcohols: dehydration, formation of ethers Aldehydes: formation from primary alcohols Ketones: formation from secondary alcohols Carboxylic acids: + alcohol = ester + amine = amide Esters: formation from acids Amides: formation from amines, acids (1) Alkanes C2H6 + O2 oxidation of alkanes by oxygen results in CO2 and water, generally thus, C2H6 + 5 O2 2 CO2 + 3 H2O C2H6 + Cl2 chlorination of alkanes results in substitution of Cl for H: e.g. C2H6 + Cl2 C2H5Cl + HCl C2H5Cl + Cl2 C2H4Cl2 + HCl and so on... dehydrogenation results in the production of a double bond. The most important example is the dehydrogenation of ethane to produce ethylene: C2H6 H2C=CH2 + H2 (requires a catalyst and high temperatures) (2) Alkenes, Alkynes The important thing here is the double or triple bond. Rich in electrons, chemistry will generally take place at this bond. Addition reactions add something across the double bond: e.g. H2C=CH-CH3 + H2 H3C-CH2-CH3 (i.e. hydrogenation) e.g. H2C=CH-CH3 + Cl2 HClC-CHCl-CH3 e.g. H2C=CH-CH3 + H2O H3C-CHOH-CH3 (i.e. production of an alcohol, needs a catalyst) (3) Alcohols e.g. butanol + methanol ? (in the presence of sulfuric acid and heat) Alcohols react with one another to form ethers. In this case, three ethers are possible: C4H9OH + HOC4H9 C4H9 - O - C4H9 (dibutyl ether) C4H9OH + HOCH3 C4H9 - O - CH3 (methylbutyl ether) CH3OH + HOCH3 CH3 - O - CH3 (dimethyl ether) (4) Aldehydes Formed from PRIMARY alcohols, i.e. alcohols in which the C bound to the -OH group is itself bound to only one other carbon. e.g. CH3CH2CH2OH CH3CH2HC=O (propanol propanal, requires an oxidative environment, often accomplished through metabolism in an organism) (5) Ketones Formed from SECONDARY alcohols, i.e. alcohols in which the C bound to the -OH group is itself bound to two other carbons. O OH Oxidation or 3-pentanone or diethylketone (6) Carboxylic Acids Carboxylic acid + Alcohol Ester + Water (in the presence of heat and H2SO4) e.g. acetic acid + methanol methyl acetate + water CH3COOH + HOCH3 CH3COOCH3 + H2O e.g. pentanoic acid + propanol propyl pentanoate + water C4H9COOH + HOCH2CH2CH3 C4H9COOCH2CH2CH3 + H2O Carboxylic Acid + Amine Amide + water e.g. acetic acid + ethylamine ethylacetamide + water CH3COOH + C2H5NH2 CH3CONHC2H5 + H2O e.g. hexanoic acid + benzylamine benzylhexamide + water C5H11COOH + C6H5NH2 C5H11CONHC6H5