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L3 Externals > Organic Chemistry L3 > Flashcards

Organic Chemistry L3 Flashcards

If it were easy, it would be biology (euuuugh)

1
Q

What are the two kinds of reactions alkenes undergo?

A

Addition and oxidation

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2
Q

If a colourless liquid alkene was mixed with a brown solution of Bromine (Br2), what observations would you expect to see?

A

I would expect to see the brown solution (colour from bromine) declolourise due to it decreasing in concentration, as it reacts with the colourless alkene to form a colourless haloalkane.

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3
Q

What are the four kinds of addition reactions alkenes can experience?

A

Halogenation,
Hydrogenation,
Halohydrogenation,
and hydration.

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4
Q

Does Halogenation require any reagents or conditions that deviate from standard conditions to proceed, what does it produce?

A

No,
Di-haloalkanes

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5
Q

Does hydrogenation require any reagents or special conditions, and what does it produce?

A

Yes, It requires a platinum catalyst.
It produces alkanes.

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6
Q

Does hydration of alkenes require any reagents, and what does it produce?

A

Yes, It requires concentrated sulfuric acid (H2SO4).
It produces alcohols.

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7
Q

Does halohydrogenation require any special reagents, and what does it produce?

A

No. It produces haloalkanes.

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8
Q

An alkene is mixed with acidified potassium permanganate. What reaction is taking place, what is produced, and what observations would you expect to see?

A

Oxidation is happening, a diol is produced, and I would expect to see the purple permanganate decolourise, as a colourless diol is produced.

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9
Q

What two reactions are used as tests for unsaturation (a double bond being present)?

A

Halogentation and oxidation with permanganate.
In both, decolourisation is a sign of an usaturated material being present.

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10
Q

What kinds of groups tend to attach the carbon in a haloalkane reactive site? (think of electron density)

A

Nucleophiles (negative groups are attracted to the partial positive charge, due to dipole created by halogen group)

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11
Q

What substitutions can occur to a haloalkane?

A

Amine substitution and hydroxyl substitution

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12
Q

What kind of haloalkane is most likely to undergo hydroxyl substitution (as opposed to elimination)?

A

Primary haloalkanes

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13
Q

What are the products of hydroxyl substitution with haloalkanes, and are any special conditions needed?

A

An alcohol and halide (which often forms a salt with whatever cation was bonded to the hydroxyl).
Normal, low temperature, and aqueous solution make it more likely, as well as non-concentrated hydroxide.

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14
Q

What are the products of amine substitution with halogens, and are any special conditions needed?

A

An amine and a halide are produced.
Conc. NH3 needed, and an alcoholic solvent.

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15
Q

What are the products of haloalkane elimination, and what conditons (and what kind of haloalkane) make it more likely?

A

An alkene, a halide, and a water molecule (a hydroxide that accepts another hydrogen) are produced.
Alcoholic conditions, high temperature, and conc. OH- make the conditions better, and a tertiary haloalkane is more likely to be eliminated.

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16
Q

What is Zaitzev’s rule in simple terms?

A

The poor get poorer (in terms of hydrogens)

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17
Q

Say you have a primary haloalkane, but don’t know specifically what kind of halogen is bonded on. You also had NaOH and water, as well as AgNO3 (silver nitrate). How could you distinguish between the products of a chloroalkane, a bromoalkane, or an iodoalkane?

A

Hydroxyl substitution will occur, and the halogen will turn to an uncombined halide. Silver salts are mostly insoluble (a precipitate will form), and a silver halide salt will form. A silver bromide salt will be off-white, a silver chloride salt will be white, and an silver iodide salt will be pale yellow.

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18
Q

Can tertiary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?

A

They do not undergo oxidation reactions

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19
Q

Can secondary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?

A

Yes. They produce ketones, and the mixture must be refluxed (ketones have a low boiling point)

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20
Q

Can primary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?

A

Yes. If a weak oxidant (like dichromate) is used and the mixture is distilled, an aldehyde can be produced. If a strong oxidant (like permanganate) is used and the mixture is refluxed, a carboxylic acid is produced.

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21
Q

What are the two ways to substitute the hydroxyl group on an alcohol with a halide?

A

There is using conc. hydro halide,
and using thionyl chloride

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22
Q

Which is the better way to turn an alcohol into a haloalkane, and why?

A

By using thionyl chloride, as more haloalkane is produced, and the other products are easier to separate.

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23
Q

What conditions are needed to get an alcohol to eliminate into an alkene?

A

Heat and conc. H2SO4 (no water)

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24
Q

What is the difference between conditons of the alcohol-alkene and alkene-alcohol reaction?

A

In the alkene-alcohol reaction, conc. H2SO4
AND H20.
In the alcohol-alkene reaction, conc. H2SO4

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25
Q

If I had a primary alcohol and I wanted an aldehyde, how would I get it?

A

React alcohol with dichromate in a distilling setup. The distillate will be an aldehyde.

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26
Q

What kind of alcohol is needed to produce a ketone?

A

A secondary alcohol.

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27
Q

What would be an effective test for the prescence of an amine?

A

Damp red litmus paper (the dampness (i.e. water) would cause the amine to form hydroxide ions, which would turn the paper blue). Amines are the only strongly basic functional group present at L3.

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28
Q

Can amines undergo any substitution reactions? If so, what are they, and what is required for them to proceed?

A

Yes, amines can undergo substitutions with chlorine (or other halogens), and haloalkanes. Thionyl chloride is required for chlorination of amines, while a haloalkane can be substituted on to form secondary or tertiary amines (only primary amines can undergo this reaction).

29
Q

What conditions are needed for the halogenation of alkanes?

A

UV light is needed to catalyse the reaction (and a molecular halogen or a halide must be present)

30
Q

What is the reagent for reducing aldehydes and ketones?

A

Sodium bromohydride (NaBH4)

31
Q

What are two tests for the prescence of an aldehdye?

A

Tollen’s test and the use of Benedict’s solution

32
Q

If an aldehyde is present, what do you expect to see with tollun’s reagent?

A

A film of reflective silver forming around the edge of the container

33
Q

If an aldehyde is present, what do you expect to see with Benedict’s solution?

A

The blue solution will turn brick red in colour

34
Q

What chemically stets aldehydes and ketones apart (Hint: this different is what makes tollun’s and Benedicts’ test possible)

A

The reactive site on an aldehyde has a C-H bond, meaning it can be oxidised further (in tollun’s test, the aldehyde reduces silver ions into silver, while in Benedicts’ test it reduces Cu(II) ions into red CU(I) ions.

35
Q

If a ketone and sodium borohydride are combined, what reaction will occur, and what will be produced?

A

Reduction will occur, and a secondary alcohol will be produced

36
Q

If an aldehyde and sodium borohydride are combined, what reaction will occur, and what will be produced?

A

Reduction will occur, and a primary alcohol will be produced.

37
Q

How can an acyl chloride be produced form a carboxylic acid?

A

With thionyl chloride.

38
Q

What are the products of the chlorination of a carboxylic acid with thionyl chloride?

A

acyl chloride, sulfur dioxide, and hydrochloric acid

39
Q

What kind of reaction involves the combining of two molecules?

A

Condensation reaciton

40
Q

What is produced in the condensation of a carboxylic acid and an alcohol, and what reagent is used?

A

An ester is produced, as well as water, and sulfuric acid is used.

41
Q

Why is sulfuric acid used as a reagent in the condensation of alcohol and carboxylic acid?

A

It catalyses the reaction, and removes water produced. This is because esters react with water.

42
Q

What is produced in the condensation of an amine and a carboxylic acid?

A

A secondary amide.

43
Q

How does a carboxylic acid make a solution acidic?

A

A hydrogen is removed from the hydroxyl group, which combines with water to produce an acidic hydronium ion.

44
Q

What is combined with a carboxylic acid to create an ester?

A

An alcohol

45
Q

What are the two condensation reactions that can form an ester?

A

Carboxylic acid + alcohol
and Acyl chloride + alcohol

46
Q

Why is acyl chloride so reactive?

A

It has a very stable leaving group in Cl-.

47
Q

What would I need to combine to get a primary amide?

A

An acyl chloride and ammonia

48
Q

What is produced in the condensation reaction between an amine and an acyl chloride?

A

A secondary amide
(like in polyamide or protein condesnation reactions)

49
Q

When ammonia and an ethanoyl chloride are combined, a white solid and an white smoke are seen. What are they?

A

The solid is ethanamide, while the smoke is hydrochloric acid.

50
Q

What is produced when acyl chloride undergoes hydrolysis?

A

A carboxylic acid and and hydrochloric acid.

51
Q

What is hydrolysis?

A

The breakdown of a molecule due to water (usually an acidic or alkaline solution)

52
Q

What are the three ways esters can be hydrolysised?

A

With an acidic solution, with a solution basic due to a hydroxyl salt, and with a solution basic due to ammonia.

53
Q

What is the reaction of an ester in an acidic solution?

A

ester —> alcohol + carboxylic acid

54
Q

What is the basic reaction of an ethyl propanoate in a solution with conc. KOH?

A

ethyl propanoate —> ethanol + potassium propanoate
(carboxylic acid is produced, but it reacts with the OH ions to become an ion)

55
Q

What is the more common name for ester hydrolysis with conc. hydroxide salt?

A

Saponification
(Fats or oils are an ester of long-chained carboxylic acids (fatty acids) and a kind of tri-alcohol, propan-1,2,3-triol, better known as triglyceride. The whole structure is called a trilaurate. When hydrolysised with hydroxide, it forms triglyceride and long carboxylate ion, which is a kind of soap (it has an ionic side and a non-ionic, non-polar side, it sticks to all kinds of molecules)

56
Q

What is the general reaction for hydrolysis of esters with ammonia?

A

Ester —> alcohol + amide

57
Q

Can amides be hydrolysed?

A

Yes

58
Q

If ethanamide is hydrolysed in strongly basic conditions, what are the products?

A

An ethanoate ion, and ammonia (no spare H+ for ammonium ion)

59
Q

If ethanamide is hdyrolysed with conc. hydrochloric acid, what are the products?

A

Ethanoic acid, and ammonium chloride (amino group gains H+ ions from solution and forms a salt)

60
Q

What are the three kinds of condensation polymers that are studied at L3, and what kinds of bond do they have?

A

Polyesters (–R-CO-O-R–)
Polyamides (–R-CO-NH-R–)
Proteins (–R-CO-NH-R–)

61
Q

What are the monomers (or monomer) of a polyester?

A

It is either a:
Dicarboxylic acid and diol
Diacyl chloride and diol
Just a hydroxy-carboxylic acid
Just a hydroxy-acyl chloride

62
Q

Are special conditions needed to condense any of these monomers?

A

If a dicarboxylic acid is used, sulfuric acid needs to be present to dehydrate (H20 is produced) and catalyse.
This is not needed with a diacyl chloride, as no water is produce and it is more reactive.

63
Q

What are the basic reactions for polyester hydrolysis under acidic and basic conditions?

A

(H30+)
polyester –> diol + dicarboxylic acid
(OH-)
polyester –> diol + dicarboxylate ion/salt

64
Q

What are the possible monomers for polyamides?

A

Diamine + dicarboxylic acid
Diamine + diacyl chloride

65
Q

What is the main difference between the protein monomer(s) and the polyamide monomer(s)?

A

Proteins have monomers with both a carboxyl/acyl group and an amino group.
Polyamides have dicarboxyl/acyl and diamines as monomers.
(in addition, in a protein, the peptide bonds are always the same way round because of this fact)

66
Q

What are the products of polyamide hydrolysis in basic conditions?

A

A dicarboxylate (the diacid reacts with the hydroxide ions, becoming an ion or salt) and a diamine (it stays the same in basic conditions)

67
Q

What are the produces of polyamide hydrolysis in acidic conditions?

A

A diacid, and a diamine salt
(the amino groups accept a H+ ion and become charge NH3+ groups)

68
Q
A

L3 Externals (3 decks)

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