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chemistry > amines, amino acids and proteins > Flashcards

amines, amino acids and proteins Flashcards

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1
Q

what is an amine

A

an amine is an organic compound derived from ammonia in which one or more hydrogen atoms have been replaced by a carbon chain or ring

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2
Q

what is an aliphatic amine

A

an aliphatic amine has the nitrogen atom attached to atleast one straight or branched carbon chain

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3
Q

what is an aromatic amine

A

aromatic amines have the nitrogen atom attached to an aromatic ring

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4
Q

why are amines important

A
  • intermediates in the production of dyestuffs , explosives and drugs
  • amines and derivatives are used as drugs to treat malaria and sleeping sickness
  • amines are used to make some plastics eg . nylon
  • fish oils contain amines
  • carboxylic acids with amine groups are called amino acids
  • quaternary amine salts are used in detergents
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5
Q

how do we name primary amines

A
  • alkyl chain attached is a prefix and add amine after
    eg - methylamine
  • unless nitrogen atom is attached elsewhere on the chain of the alkyl group eg carbon 2 then it becomes
    2- amino (alkyl) eg 2-aminobutane
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6
Q

how do we name secondary amines

A
  • if they have the same alkyl group we use di + alkyl group + amine eg dimethylamine

-with different groups N is used and it is named as an N substituted derivative of the larger group so first we name normally with larger group eg propylamine and then add N- alkyl
eg N-methylpropylamine

( it is not in alphabetical order )

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7
Q

how do we name tertiary amines

A
  • if it is the same group we use tri + alkyl group eg trimethylamine
  • if it is different groups we look for the longest chain , then we order the next two alkyl groups alphabetically using N,N eg N-ethyl,N-methylpropylamine
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8
Q

why are amines bases

A

they have a lone pair which means they can accept protons , when they accept a proton , a dative covalent bond is formed between the nitrogen atom and the proton

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9
Q

what forms when an amine reacts with a H+ ion

A
  • an ion is formed
  • to name we add ammonium ion to the origonal name
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10
Q

what happens when an amine reacts with an acid

A

a salt of the amine is formed

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11
Q

reaction of methyl amine and HCl makes what

A

methylammonium chloride
(CH3NH3+Cl-)

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12
Q

reaction of methyl amine and sulfuric acid makes what

A

methylammonium sulphate
(CH3NH3+)2 SO42-

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13
Q

how do we make a primary aliphatic amine

A
  • gentle warming with a halogenoalkane
  • excess concentrated ammonia (NH3)
    -use ethanol
    -nucleophillic substitution
  • produces an ammonium salt which we then react with NaOH to deprotonate and generate the amine
  • this produces water and NaCl
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14
Q

why is an excess of concentrated ammonia used

A
  • reduces further substitution of the amine group and formation of secondary and tertiary amines
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15
Q

why is ethanol used as a solvent

A

to prevent any substitution of the haloalkane by water to produce alcohols

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16
Q

why is this classed as a nucelophillic subsitution reaction

A

ammonia has a lone pair of electrons and therefore can act as a nucleophile

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17
Q

how do we form a secondary aliphatic amine

A

we use the primary amine formed which will still contain a lone pair of electrons so can attack the carbon on another halogenoalkane to produce a salt which is then deprotonated

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18
Q

how do we form a tertiary amine

A
  • the secondary amine produced still contains a lone pair of electrons so can attack another halogenoalkane
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19
Q

how do we make aromatic amines

A
  • reduction of nitrobenzene using
    tin and concentrated HCl
    ( conc. hcl and sn)
    heated under reflux to form the ammonium salt which is then reacted with excess sodium hydroxide to form the aromatic amine phenylamine
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20
Q

why is making aromatic amines much harder than aliphatic amines

A
  • ammonia reacts much more slowly with chloroarenes than chloroalkanes
  • ammonia is a nucelophille and the delocalised pi eletron cloud of a chloroarene repels the lone pair of an approaching ammonia molecule
  • also the c-cl bond is stronger in the chloroarene due to delocalisation of electron density from the ring with the bond
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21
Q

how many different amino acids are there

A

20

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22
Q

what functional groups does an amino acid contain

A
  • a basic amine group
    -an acididc carboyxl group
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23
Q

what are alpha amino acids

A
  • amine group and carboxyl group are attached to the same carbon atom
24
Q

what is the general formula for an amino acid

A

RCH(NH2)COOH

25
Q

why are amino acids amphoteric( can act as an acid or a base)

A
  • they possess acidic and basic properties due to their amine and carboxyl functional groups
26
Q

how do amines form salts

A
  • the amine group is basic and therefore this reacts with acids to form salts . the amino acid is behaving as a base to accept a proton from the acid , this forms a positively charged ion
    -eg amino acid + HCl–> ammonium salt + cl-
27
Q

how does it produce salts from the carboxyl group

A
  • the carboyxlic acid group can react with alkalis to form salts ( the H from the OH- is replaced with a metal ion and h20 is also produced )
  • it can also react with alcohols to form esters
28
Q

how do amino acids form esters

A
  • heat amino acid and alcohol with a small amount of concentrated sulfuric acid
    -the carboxylic acid group is esterified , producing an ester and water
    -the acidic conditions also protonate the basic amino group of the ester.
29
Q

what happens to amine groups when in acidic conditions

A
  • the basic amino group is protonated
30
Q

how do amines and ammonia act as nucleophiles

A

by donating their lone pair of electrons on the nitrogen atom to an electron deficient species ( eg the c=o bond of an acyl chloride)

31
Q

how do you determine whether an amide is primary , secondary or tertiary

A
  • depending on the number of carbon atoms attached to the nitrogen - the double bond carbon is 1 of these
32
Q

what is optical isomerism

A

a type of stereoisomerism

33
Q

what are the features of optical isomerism

A

-occurs in organic molecules containing a carbon atom attached to 4 different atoms or groups of atoms
-this is known as a chiral carbon or chiral centre
- two mirror image arrangements possible
-arrangements are non -superimposable , called optical isomers or enantiomers
-they are chemically identical but rotate plane -polarised light in different directions.

34
Q

what is the key definition for a chiral carbon

A
  • a carbon atom attached to 4 different atoms or groups of atoms
35
Q

what is the key definition for optical isomers/ enantiomers

A
  • stereoisomers that are non -superimposable mirror images of each other
36
Q

how do you draw optical isomers

A
  • tetrahedral shape around the carbon atom. draw mirror images and draw a dotted vertical line between them to show that they are mirror images , making sure to swap alkyl groups round eg CH3 is now H3C
37
Q

what do all alpha amino acids have in common ( apart from glycine )

A

they all contain a chiral carbon
- this can also be known as ‘optically active’

38
Q

what is a racemic mixture

A

a mixture with equal amounts of each isomer , it therefore has no effect on plane polarised light as the rotations cancel each other out

39
Q

how do you calculate the number of optical isomers

A

when the molecule is unsymmetrical and contains ‘n’ chiral carbon atoms , the total number of optical isomers is 2^n

40
Q

what is the definition for polymerisation

A

a reaction in which small molecules called monomers join together to make large molecules consisting of repeating units

41
Q

what are the two types of polymerisation

A

condensation and addition

42
Q

what are the differences between condensation and addition polymerisation

A
  • addition involves an alkene where the pi bond is broken enabling connecting covalent bonds to be formed
    -forms a continuous backbone of carbon atoms
    -involves no loss of atoms /molecules
  • atom economy is 100%
  • condensation requires monomers with two different functional groups
    -this is because a functional group on one monomer unit bonds to a different functional group on another monomer unit.
    -polyesters and polyamides are common condensation polymers
    -a small molecule is produced / eliminated
43
Q

what is condensation polymerisation

A

a reaction in which two small molecules react together to form a larger molecule , with the elimination of a small molecule such as water or HCl

44
Q

how do you form a polyester

A

monomer units are bonded by ester linkages and these monomers have functional groups carboxyl and hydroxyl ( cooh and oh)
- water is eliminated
-this can be done by either reacting two different monomer units ( one is a doil and one is a diocacid )
-or polyesters can be formed by reacting just one type of monomer together containing both an alcohol and carboxyl group.

45
Q

when forming a polyester from diol and dicarboxylic acid monomers how many water molecules are produced

A
  • (2n-1)H20 , where n is the number of each polymer
46
Q

how many water molecules are produced from one monomer type

A

(n-1)H20

47
Q

what is the key definition for a repeat unit

A

the specific arrangement of atoms that occurs in the structure over and over again . repeat units are included in brackets , outside which is letter n

48
Q

when making a polyester , what other compound could we use with a diol instead

A

we could use a diacyl chloride with a diol , this would produce the polyester and HCl as a small molecule

49
Q

how do you form polyamindes

A

polyamides are formed from monomers that contain a carboxyl group and an amine group or an acyl chloride instead of a carboxyl group
- you can do this by either reacting two different monomer units , 1 being a diamine and the other a dicarboxylic acid or one monomer with both functional groups

50
Q

what bond do polyamides contain

A

an amide bond , this is C=O-NH

51
Q

how do you hydrolyse polyamides and polyesters

A
  • either acid hydrolysis using hot , aqeous acid or base hydrolysis / alkaline hydrolysis using hot aqueous alkali
52
Q

what is produced from the base hydrolysis of polyesters

A
  • carboxylate salt and alcohol , any carboxyl groups are deprotonated
53
Q

what is produced from the acid hydrolysis of polyesters

A

-an alcohol and a carboxylic acid

54
Q

what is produced from the base hydrolysis of polyamides

A

carboxylate salt and amine

55
Q

what is produced from the acid hydrolysis of polyamides

A

carbpxylic acid and all NH groups are protonated

56
Q

describe how polyesters and polyamides are biodegradable

A

Polyesters and polyamides are biodegradable polymers for a number of reasons
One such reason is their ability to breakdown with the use of light
Carbonyl groups (C=O) along polymer chains are able to absorb energy from the Electromagnetic Spectrum, in particular ultraviolet (UV) light
Absorbing UV light weakens the carbonyl areas of polymers and breaks them down into smaller molecules

chemistry (24 decks)

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