Functional Groups

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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

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Halides R-X where R is any alkyl group, and X a
halogen CH3Cl - chloromethane C6H5Cl -
chlorobenzene Synthesis radical chain reaction
between an alkane and a halogen CH4 Cl2 CH3Cl
HCl Cl2 2Cl Cl CH4 ? HCl
CH3 CH3 Cl2 ? CH3Cl Cl
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• Alcohols R-OH hydroxyl functional group
• Nomenclature - use the suffix ol
• CH3-CH2-OH ethanol
• CH3-CH2-CH2OH 1-propanol

Primary alcohol
Secondary alcohol
Tertiary alcohol
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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- CH3Br ? CH3OH Br- Addition
across a double bond CH2CH2 H2O
CH3CH2OH
Charge distribution in ethanol red indicates
negative charge
300 - 400oC 60 - 70 atm
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Phenols hydroxyl group attached directly to an
aromatic ring
Phenol (C6H5OH) weak acid, Ka 1 x 10-10
stability of the phenolate ion (C6H5O-)
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Oil of thyme
Oil of clove
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• Ethers R - O - R
• C2H5 - O - C2H5 diethylether
• C6H5 - O - C2H5 ethylphenylether
• Synthesis
• 2 R-OH R - O - R H2O

Kinetics vs thermodynamics
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• Aldehydes and Ketones

carbonyl group
aldehyde
ketone
HCHO formaldehyde CH3CHO acetaldehyde CH3COCH
3 dimethlyketone (acetone)
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• Properties of aldehydes and ketones differ
  because of the aldehyde H atom
• CH3CH2OH CH3CHO
• 1o alcohol aldehyde
• ethanol acetaldehyde
• (CH3)2CHOH (CH3)2CO
• 2o alcohol
• 2-propanol dimethylketone

O2, catalyst, high temperatures
O2, catalyst, high temperatures
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almond and cherries
vanilla
cinnamon
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• Carboxylic acids -COOH functional group

HCOOH - formic acid (ant venom) CH3COOH - acetic
acid (vinegar) Carboxylic acids hydrogen bond -
dimers Synthesis Catalytic oxidation of
aldehydes CH3CHO CH3COOH
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• Esters R-COO- R

acetic acid ethanol ethylacetate
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Fats (solids) and oils (liquids) are triesters
formed from glycerol and three carboxylic acids
(fatty acids)
Tristearin animal fatty acid tri-esters CH2OHCHOH
CH2OH 3 CH3(CH2)16COOH glycerol stearic
acid
Saturated - C-C single bonds Unsaturated - one
(mono-unsaturated) or more (polyunsaturated) CC
bonds
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• Amines

ammonia
primary amine (1o)
secondary amine (2o)
tertiary amine (3o)
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• CH3NH2 methylamine
• (CH3)2NH dimethylamine
• (CH3)3N trimethylamine
• C6H5NH2 aniline

Amines are bases NicH2(aq) 2 NH3(aq) ?
Nic(aq) 2 NH4(aq) Synthesis of
amines a) Naturally occurring b) NH3 CH3Cl ?
CH3NH2 HCl
nicotine
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• Amino acids carboxylic acid containing an amine
  group
• Glycine NH2CH2COOH

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cationic form predominant in acidic solutions
anionic form predominant in basic solutions
dipolar form - zwitterion
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Amides -CONH2- group Formed by reaction between
NH3 or 1o or 2o amine and acid
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glycine glycine
diglycine H2O
Proteins polypeptides with CONH linkage between
amino acids
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