Functional Groups A functional group is a small group of atoms that lend characteristic properties to the molecule Properties of the molecule are dictated by the functional groups; allows for systematic study of organic molecules

Halides: R-Xwhere R is any alkyl group, and X a halogen CH 3 Cl - chloromethane C 6 H 5 Cl - chlorobenzene Synthesis: radical chain reaction between an alkane and a halogen CH 4 + Cl 2 CH 3 Cl + HCl Cl 2 2Cl Cl + CH 4  HCl + CH 3 CH 3 + Cl 2  CH 3 Cl + Cl h or heat

Alcohols: R-OH hydroxyl functional group Nomenclature - use the suffix “ol” CH 3 -CH 2 -OHethanol CH 3 -CH 2 -CH 2 OH1-propanol Primary alcohol Secondary alcohol Tertiary alcohol

Presence of OH group allows hydrogen bonding As the C chain becomes longer the OH group becomes less important Synthesis of alcohols Hydrolysis of a alkyl halide with a strong base OH - + CH 3 Br  CH 3 OH + Br - Addition across a double bond CH 2 =CH 2 + H 2 O CH 3 CH 2 OH Charge distribution in ethanol; red indicates negative charge o C atm

Phenol (C 6 H 5 OH) weak acid, K a = 1 x ; stability of the phenolate ion (C 6 H 5 O - ) Phenols: hydroxyl group attached directly to an aromatic ring

Oil of thyme Oil of clove

Ethers: R - O - R C 2 H 5 - O - C 2 H 5 diethylether C 6 H 5 - O - C 2 H 5 ethylphenylether Synthesis: 2 R-OH R - O - R + H 2 O H 2 SO 4 CH 3 -CH 2 -OH + H 2 SO o C CH 3 -CH 2 -O-CH 2 -CH 3 + H 2 O H 2 SO o C 2CH 2 =CH H 2 O Kinetics vs thermodynamics

Aldehydes and Ketones carbonyl group aldehyde ketone HCHO: formaldehyde CH 3 CHO: acetaldehyde CH 3 COCH 3 : dimethlyketone (acetone)

Properties of aldehydes and ketones differ because of the aldehyde H atom CH 3 CH 2 OH CH 3 CHO 1 o alcohol aldehyde ethanol acetaldehyde (CH 3 ) 2 CHOH (CH 3 ) 2 CO 2 o alcohol 2-propanol dimethylketone O 2, catalyst, high temperatures O 2, catalyst, high temperatures

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Carboxylic acids: -COOH functional group HCOOH - formic acid (ant venom) CH 3 COOH - acetic acid (vinegar) Carboxylic acids hydrogen bond - “dimers” Synthesis Catalytic oxidation of aldehydes CH 3 CHOCH 3 COOH O 2, Mn 2+

Esters:R-COO- R’ acetic acid + ethanol ethylacetate

Tristearin: animal fatty acid tri-esters CH 2 OHCHOHCH 2 OH + 3 CH 3 (CH 2 ) 16 COOH glycerol stearic acid Fats (solids) and oils (liquids) are triesters formed from glycerol and three carboxylic acids (fatty acids) Saturated - C-C single bonds Unsaturated - one (mono-unsaturated) or more (polyunsaturated) C=C bonds

Amines: ammonia primary amine (1 o ) secondary amine (2 o ) tertiary amine (3 o )

CH 3 NH 2 methylamine (CH 3 ) 2 NHdimethylamine (CH 3 ) 3 Ntrimethylamine C 6 H 5 NH 2 aniline Amines are bases: NicH 2 + (aq) + 2 NH 3 (aq)  Nic(aq) + 2 NH 4 + (aq) Synthesis of amines a) Naturally occurring b) NH 3 + CH 3 Cl  CH 3 NH 2 + HCl nicotine

Amino acids: carboxylic acid containing an amine group Glycine: NH 2 CH 2 COOH

cationic form predominant in acidic solutions anionic form predominant in basic solutions dipolar form - zwitterion

Amides: -CONH 2 - group Formed by reaction between NH 3 or 1 o or 2 o amine and acid

Proteins: polypeptides with CONH linkage between amino acids glycine + glycine diglycine + H 2 O