amines, amino acids and polymers Flashcards

1
Q

what are amines?

A

organic compounds derived from ammonia, NH3, in which one or more hydrogen atoms in ammonia have been replaced by an organic group (alkyl group)

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2
Q

what are the different types of amine?

A

primary, secondary, tertiary and quaternary

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3
Q

what is an aliphatic amine?

A

the nitrogen atom is attached to at least one straight or branched carbon chain

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4
Q

what is an aromatic amine?

A

the nitrogen atom is attached to an aromatic ring

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5
Q

Why are amine bases?

A

lone pair of electrons on nitrogen atom can accept a proton

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6
Q

How do amines bond?

A

proton bonds to amine via a dative covalent (coordinate) bond. Both electrons in the bond originate from the lone pair on the nitrogen

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7
Q

The strength of the amine base is dependent on what?

A

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.

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8
Q

The electron density on nitrogen in an amine is dependent on what?

A

dependent on the type of group attached to the nitrogen

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9
Q

How are aliphatic amines made?

A

-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.

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10
Q

what are the products formed during amine formation using NaOH?

A

amine + salt + water

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11
Q

what are the essential conditions needed for the preparation of amines?

A

-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.

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12
Q

What is the disadvantage of making primary amines in this way?

A

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

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13
Q

how is the secondary amine obtained?

A

salt reacts with NaOH
products: secondary amine, salt and water

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14
Q

what are the two ways in which aliphatic amines are made?

A

-by reacting a halogenoalkane with excess ammonia
-by reducing a nitrile

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15
Q

what are the two ways in which aliphatic amines are made?

A

-by reacting a halogenoalkane with excess ammonia
-by reducing a nitrile

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16
Q

How are aliphatic amines made by reducing a nitrile?

A

two amine are used

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17
Q

How are aromatic amines made?

A

by reducing nitro compounds (e.g nitrobenzene).

18
Q

Why are aromatic amines useful?

A

used to make dye stuffs and pharmaceuticals

19
Q

What are the steps when producing aromatic amines?

A

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.

20
Q

What are amides?

A

derivatives of carboxylic acids and have a functional group of -CONH2

21
Q

Describe the structure of a secondary amide?

A

one of the nitrogens attached to a hydrogen, in the amide group, is replaced by an alkyl group.

22
Q

Describe amino acids?

A

-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

23
Q

What is the R-group of glycine?

A

hydrogen

24
Q

what are chiral molecules?

A

molecules where central carbon atom is attached to four different groups. They rotate plane polarised light.

25
Q

what are a-amino acids?

A

where both NH2 and COOH are attached to the same carbon. These are the most common amino acids.

26
Q

Amino acids react with acids and alkalis to form what?

A

salts

27
Q

Describe the reaction between amino acids and alkali?

A

alkalis react with the carboxylic acid group in amino acids to form a conjugate base- RCH(NH2)COO- which combines with a positive ion to form an amino salt and water

28
Q

Describe the reaction between amino acid and acid?

A

acids react with amino group (NH2) to form a conjugate acid

29
Q

Describe the reaction between amino acids and alcohols?

A

alcohol reacts with the carboxylic acid group in amino acids to form an ester. Sulphuric acid catalyst is used.
amino acid + alcohol -> ester + water

30
Q

what is optical isomerism?

A

form of stereoisomerism, they have the same structural formula but different arrangement of atoms in space. Optical isomers are mirror images and have a chiral carbon atom.

31
Q

What are enantiomers?

A

mirror images of each other and are non-superimposable.

32
Q

amides are products of what reaction?

A

reaction between acyl chlorides with ammonia and amides

33
Q

How are optically active isomers detected?

A

standard light oscillates in all directions. When light is passed through a Polaroid filter it oscillates in one direction. Optically active isomers will rotate the plane polarised light- one enantiomer rotates clockwise and the other, anticlockwise.

34
Q

chiral carbon atom is labelled with what?

A

asterisk

35
Q

Describe addition polymers

A

-alkenes are monomers which join to form addition polymers
-poly(alkenes) are saturated molecules, normally non-polar and hence unreactive

36
Q

What is condensation polymerisation?

A

2 different monomers with at least 2 functional groups react together. When they react, a link (amide or ester link) is made and water is eliminated (condensation)

37
Q

What are the two types of polymers which can be synthesised from condensation polymerisation?

A

polyamides- formed by reacting diamines with dicarboxylic acids
polyesters- formed by reacting a diol(two hydroxyl groups) and carboxylic acid together

38
Q

Describe the hydrolysis of condensation polymers

A

-water can be used to produce the original monomers
-alkali or acid can be used

39
Q

How can a condensation polymer contain amide and ester links?

A

molecules with amine and alcohol groups can react with dicarboxylic acids

40
Q

how can condensation polymers be formed from one type of monomer?

A

molecules with a carboxylic acid and either an alcohol or amine group can react with itself