P-Chem Functional Groups

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Nomenclature of Alcohols

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Alcohols are slightly acidic (pKa ~ 16).

Alcohol oxygen atoms behave as Lewis bases.

Alcohols can react as either bases or nucleophiles at the oxygen.

The -OH group is a poor leaving group and needs to be converted to a better leaving group before substitution can occur.

Removal of the proton generates the alkoxide.

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Halogenated Compounds

Functional group suffix =  halide (i.e. fluoride, chloride, bromide, iodide)

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Diols

HOCH2CH2OH = 1,2-ethanediol

Functional group prefix = dihydroxy-

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Phenol

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Ethers

Functional group suffix =  ether Functional group prefix = alkoxy-

Physical Properties:

The polar nature of the C-O bond (due to the electronegativity difference of  the atoms ) results in intermolecular dipole-dipole interactions.

An ether cannot form hydrogen bonds with other ether molecules since there is no H to be donated (no -OH group)

Ethers can be involved in H-bonding with systems able to donate H (e.g. water).

The implications of these effects are:

**lower melting and boiling points compared to analogous alcohols
solubility in aqueous media generally slightly less to analogous alcohols.

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Epoxides

Epoxides are just a sub-class of ethers, in that they contain the C-O-C unit. 

However, the term "epoxide" is used to describe the 3 membered heterocyclic system.

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Aldehydes and Ketones

Nomenclature: 

Aldehydes: functional group suffix = -al

Ketones: functional group suffix = -one

Physical Properties:

The polar nature of the C=O (due to the electronegativity difference of the atoms) means dipole-dipole interactions will occur.

Though C=O can not hydrogen-bond to each other, the C=O can accept hydrogen bonds from hydrogen bond donors (e.g. water, alcohols).

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Sulfur --> thiols, thioethers and disulfides

Physical Properties:

Hydrogen bonding is much weaker than that in alcohols.

Lower boiling points than similar alcohols.

Generally similar to alcohols, but bonds to S are longer and weaker than those to O.
The thiol functional group consists of an S atom bonded to a C atom and a H atom via s bonds.

The S-H bonds is less polar than that in alcohols since S is less electronegativity than O.

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Amines

The amine functional group consists of an N atom bonded either to C or H atoms via s bonds.

Both the C-N and the N-H bonds are polar due to the electronegativity of the N atom.

The trigonal pyramidal arrangement of bonds around nitrogen is shallower in aryl amines vs alkyl amines.

This is a result of resonance delocalisation of the lone pair into the aromatic p system (such delocalisation is also responsible for the decreased basicity of aryl vs alkyl amines).

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Carboxylic Acids Derivatives

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Pharmacological Amines

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Esters

Cyclic esters are called lactones

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Anhydrides

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Amides

Cyclic amides are called lactams

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Carbonates, Carbamates, and Ureas

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Functional Groups (Overview)

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