Chapter 27: Amines, Amino Acids, and Proteins (27.1 - 27.3) Flashcards

1
Q

Formula of ammonia

A

NH3

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2
Q

What are amines

A

Amines are an organic compound formed when one or more hydrogen atoms in ammonia has been replaced by a carbon chain or ring

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3
Q

What is an aliphatic amine

A

The nitrogen atom is bonded to at least one alkyl group (straight or branched carbon chain)
Simplest is methylamine, CH3NH2, with one methyl group attached to the nitrogen

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4
Q

What is an aromatic amine

A

Nitrogen atom is attached to an aryl group (aromatic ring)

Simplest is phenylamine, C6H5NH2, with a phenyl group attactehd to the nitrogen atom

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5
Q

How are amines classified

A

Primary: R-NH2. N at attached to 1 R group
Secondary: N attached to 2 R groups (and 1 H)
Tertiary: N attatched to 3 R groups

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6
Q

How do you make a polyester from one monomer?

A

The monomer must contain both a hydroxyl and a carboxyl group

Carboxylic acid reacts with alcohol, forming an Ester linkage and water

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7
Q

How are polyesters made from two monomers?

A

When one monomer is a diol and one is a carboxylic acid

A hydroxyl group reacts with the carboxyl group, forming an Ester link and water

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8
Q

What two ways can you make a polyamide From one monomer?

A

With an amino acid which has an amine group and a carboxylic acid - forms a Peptide bond and water

Monomer with an amine group and an acyl chloride - forms an Peptide bond and hydrogen chloride

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9
Q

Which two ways can you make a polyamide from two monomers?

A

Reacting a dicarboxylic acid with a diamine.

Reacting a diacyl chloride with a diamine

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10
Q

Why are polyamides and polyesters strong?

A

They will have hydrogen bonds between chains and they have very strong London forces as they are long and have lots of points of contact

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11
Q

How do you hydrolyse a polyester?

A

1) With hot aqueous alkali e.g NaOH and water - makes a dicarboxylate salt (COO-Na+) and a diol
2) With hot aqueous acid e.g HCl and water - makes a diol and a dicarboxylic avid

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12
Q

How do you hydrolyse a polyamide?

A

NaOH and water - makes a diamine and a dicarboxylate salt (COO-Na+)

H+/H2O - makes a dicarboxylic acid and a compound with an NH3+ group on either end

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13
Q

how do amines behave as bases

A

The lone pair of electors on the N atom accepts a proton

A dative covalent bond forms between the lone pain of the N atom and the H+

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14
Q

amine + acid –>

A

amine + acid –> salt
amines neutralise dilute acids to form salts
eg CH3CH2NH2 + HCl –> CH3CH2NH3+Cl-

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15
Q

aliphatic amines are prepared by:

A

1) substitution of haloalkanes with excess ethanoic ammonia to form a salt:
CH3CH2NH2 + NH3 –> CH3CH2NH3+Cl-

2) Excess ammonia substitutes the halide
CH3CH2NH3+CL- + NH3 —> CH3CH2NH2 +NH4CL

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16
Q

the use of ethanol in the preparation of aliphatic amines

A

Ethanol is a solvent, used to prevent substitution of the haloalkane by water to produce alcohols

17
Q

Aromatic amines are prepared by:

A

1) reduction of nitroarenes by refluxing with tin and concentrated hydrochloric acid

18
Q

what is an amino acid?

A

an organic compound containing both amine (NH2) and carboxylic acid (COOH) functional groups.
Because they contain both an acidic COOH and a basic NH2 functional group, amino acids have similar reactions to both carboxylic acids and amines

19
Q

what is an α-amino acid? (alpha-amino)

A

an amino acid with the NH2 and COOH groups attached to the same α-carbon atom

NH2-CH(R)-COOH
[ normally written as RCH(NH2)COOH ]

20
Q

amino acid reaction with alkalis

A

COOH group reacts with aqueous alkali to form salt and water

H2N-CH2-COOH + NaOH –> H2N-CH2-C(O)O-Na+ + H2O

21
Q

esterification of amino acids

A

COOH group can be esterified by heating with an alcohol with a concentrated H2SO4 catalyst
The acidic conditions protanone the basic NH2 to form -NH3+
H2N-CH2-COOH + C2H5OH + H+ –> H3N+-CH2-COOC2H5 + H2O

22
Q

amino acids reaction with acids

A

NH2 groups neutralise an acid to form a salt.

eg reaction with HCl would change NH2 group to NH3+ and leave a Cl- ion

23
Q

how are amides classified

A

Primary: 1 carbon atom bonded to N
Secondary: 2 carbon atoms bonded to N
Tertiary: 3 carbon atoms bonded to N

24
Q

Two types of stereoisomers?

A

2 types: optical and E/Z

25
Q

optical isomerism

A

Found in molecules that contain a chiral centre

  • a chiral carbon atom is attached to 4 different atoms or groups of atoms, often labelled with an asterisk * in diagrams
  • optical isomers are when the 4 groups attached to the chiral carbon are arranged in space as two non-superimposable mirror images
  • each chiral carbon atom in an organic molecule has one pair of optical isomers
26
Q

why do α-amino acids have optical isomers

A

all α-amino acids (except glycine H2NCH2COOH) contain a chiral carbon atom

27
Q

what is an amide?

A

R-CO-N(R’)-R’’

organic compounds that are derivatives of carboxylic acids

28
Q

hydrolysis of polyesters

A
  • acid hydrolysis produces carboxylic acid + alcohol

- alkaline hydrolysis produces carboxylate salt + alcohol

29
Q

hydrolysis of polyamides

A
  • acid hydrolysis produces carboxylic acid + ammonium salt

- alkaline hydrolysis produces carboxylate salt + an amine

30
Q

types of hydrolysis to break down a substance

A
  • Acid hydrolysis: hot aqueous acid eg. HCl (aq)

- Alkaline hydrolysis: hot aqueous alkali eg. NaOH (aq)

31
Q

Why might a polymer not have the same Mr as expected?

A

It is likely that the polymer has 2 groups on it which can react together to form a ring

32
Q

If you want one optical isomer from a synthesis what method should you use?

A

1) use enzymes or bacteria

2) Chiral catalyst