amines, amino acids and polymers
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what are amines?
organic compounds derived from ammonia, NH3, in which one or more hydrogen atoms in ammonia have been replaced by an organic group (alkyl group)
what are the different types of amine?
primary, secondary, tertiary and quaternary
what is an aliphatic amine?
the nitrogen atom is attached to at least one straight or branched carbon chain
what is an aromatic amine?
the nitrogen atom is attached to an aromatic ring
Why are amine bases?
lone pair of electrons on nitrogen atom can accept a proton
How do amines bond?
proton bonds to amine via a dative covalent (coordinate) bond. Both electrons in the bond originate from the lone pair on the nitrogen
The strength of the amine base is dependent on what?
dependent on the availability of the lone pair of electrons on the nitrogen. The higher the electron density, the more readily available the electrons are.
The electron density on nitrogen in an amine is dependent on what?
dependent on the type of group attached to the nitrogen
How are aliphatic amines made?
-reacting a halogenoalkane with excess ammonia -ammonia acts as a nucleophile in a substitution reaction with a haloalkane. -ammonium salt is made and then aqueous alkali is added to generate the amine from the salt.
what are the products formed during amine formation using NaOH?
amine + salt + water
what are the essential conditions needed for the preparation of amines?
-ethanol is used as a solvent. This prevents any substitution of the haloalkane by water to produce alcohols -excess ammonia is used. This reduces further substitution of the amine group to form secondary and tertiary amines.
What is the disadvantage of making primary amines in this way?
as the product still contains a lone pair of electrons on the nitrogen, it can react further with the haloalkane to produce a secondary amine. Further substitution can occur producing tertiary and quaternary salts too - impure products
how is the secondary amine obtained?
salt reacts with NaOH products: secondary amine, salt and water
what are the two ways in which aliphatic amines are made?
-by reacting a halogenoalkane with excess ammonia -by reducing a nitrile
what are the two ways in which aliphatic amines are made?
-by reacting a halogenoalkane with excess ammonia -by reducing a nitrile
How are aliphatic amines made by reducing a nitrile?
two amine are used
How are aromatic amines made?
by reducing nitro compounds (e.g nitrobenzene).
Why are aromatic amines useful?
used to make dye stuffs and pharmaceuticals
What are the steps when producing aromatic amines?
step 1- heat (under reflux) nitrobenzene with concentrated HCl and Sn to form a salt such as C6H5NH3+Cl- step 2- salt produced in step 1 is reacted with an alkali (NaOH) to produce an aromatic amine such as phenylamine.
What are amides?
derivatives of carboxylic acids and have a functional group of -CONH2
Describe the structure of a secondary amide?
one of the nitrogens attached to a hydrogen, in the amide group, is replaced by an alkyl group.
Describe amino acids?
-amino acids have an amino group (-NH2) and a carboxyl group (-COOH) -amino acids are amphoteric meaning they have acidic and basic properties -general formula: RCH(NH2)COOH -amino acids (except glycine) are chiral compounds
What is the R-group of glycine?
hydrogen
what are chiral molecules?
molecules where central carbon atom is attached to four different groups. They rotate plane polarised light.