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OCR Chemistry A for AS and A-Level > Module 6 > Flashcards

Module 6 Flashcards

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1
Q

What is a stationary phase (in chromatography)?

A

The phase that doesn’t move

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2
Q

What is a mobile phase (in chromatography)?

A

The phase that does move (through the stationary phase)

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3
Q

What reagents are required to halogenate benzene, and what kind of reaction is it?

A

Electrophilic substitution, requiring FeBr3 (to form Br+ electrophile), or the equivalent Fe-halogen compound

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4
Q

What reagents are required to alkylate benzene, and what kind of reaction is it?

A

Electrophilic substitution, requiring a haloalkane and a halogen carrier (e.g. FeCl3)

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5
Q

What is produced when an acyl chloride reacts with ammonia?

A

A 1” amide

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6
Q

What reagents are required to nitrate benzene and what kind of reaction is it?

A

Electrophilic Substitution reaction, requiring nitric acid and sulphuric acid (to form NO2+ electrophile)

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7
Q

How can you hydrolyse polymers?

A

Acid (NaOH + H2O) or base (H+ + H2O) hydrolysis

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8
Q

How can you turn a carbonyl into a hydroxynitrile?

A

add hydrogen cyanide (or make it in situ)

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9
Q

How can you form hydroxynitriles from a carbonyl compound?

A

Add sulphuric acid and sodium-cyanide (to form hydrogen cyanide in-situ) - good for increasing chain length

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10
Q

What effect(s) does the NO2 (nitro) group have on the benzene ring?

A

It ‘deactivates’ it, making it less able to react with electrophiles and also directing to position 3 substitutions

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11
Q

How can you reduce a Ketone?

A

2[H] (from the NaBH4) and water, to produce a secondary alcohol

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12
Q

How could ethylamine act as a base?

A

Accept a proton to become an ethylammonium ion

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13
Q

Describe the structure of the delocalised model of benzene?

A

Adjacent p-orbitals overlap sideways to form a ring of electron density above the below the plane of bonding (known as a pi-system)

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14
Q

How do you bromate phenol and what type of reaction is it?

A

Electrophilic substitution, add 3Br2, no catalyst is required

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15
Q

How can you test for a carbonyl group?

A

Add Brady’s reagent (2,4-DNP in methanol and sulphuric acid), if positive, a yellow/orange ppt forms

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16
Q

What does phenol ‘behave as if it were’?

A

A weak acid, it can partially dissociate protons from its hydroxide group

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17
Q

What is the name of the product (an ester) of the reaction between ethanoic acid and methanol?

A

Methylethanoate

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18
Q

How does a zwitterion behave at a pH higher than its isoelectric point?

A

As an acid, the inverse is true also

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19
Q

How can nitriles be hydrolysed?

A

Add water and HCl, under heat

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20
Q

What evidence is there to reject the Kekulean model of benzene?

A

Relatively unreactive
- Benzene does not undergo electrophilic addition or decolourise bromine water as it would if there were double bonds
Carbon-carbon bond length
- X-ray diffraction has shown all of the bonds to be the same length (a length in between single and double)
Hydration Enthalpies
- The enthalpy of hydrogenation is less than 3x that of cyclohexene (which would be the expected value if Kekule was right)

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20
Q

What reagents are required to acylate benzene, and what kind of reaction is it?

A

Electrophilic substitution, requiring an acyl-chloride and a halogen carrier (e.g. FeCl3)

23
Q

How can nitriles be reduced into animes?

A

Add H2 with a Ni catalyst

25
Q

In gas chromatography, what is the stationary phase and what is the mobile phase, and how are the results presented?

A

Stationary Phase: Boiling Liquid
Mobile Phase: Carrier Gas (and sample mixture)
Output is ‘retention time’

26
Q

How can carbonyls react by nucleophilic addition with NaBH4, and how with NaCN?

A

Where an intermediate is formed and then protonated, making an alcohol or a hydroxynitrile respectively

27
Q

How can you hydrolyse an ester bond?

A
  • Acid hydrolysis under reflux, with water (reversible)

- Alkali hydrolysis under reflux, with OH- ions (irreversible), produces ethanoate ions

28
Q

What are the alternate names of the 2,3 and 4 positon-substitutions?

A

2 is also known as ortho
3 is also known as meta
4 is also known as para

29
Q

How do you form a secondary anime from a haloalkane?

A

Add a primary anime then NaOH

31
Q

How does the solubility of carboxylic acids change is the chain length increases?

A

Solubility decreases, because the effect of the hydrogen bond is ‘drowned out’ by the increasing alkane chain

32
Q

How can you acylate aromatic compounds?

A

Using a halogen carrier - AlCl3 etc. and an acyl chloride (to form an aromatic keytone)

33
Q

How can you turn a haloalkane into a nitrile?

A

Add potassium cyanide

34
Q

How can you alkylate aromatic compounds?

A

Using a halogen carrier - AlCl3 etc. and a haloalkane

35
Q

How can you prepare an organic solid?

A

Reduced-pressure filtration, using a Buchner funnel and flask
Recrystallization, adding the hot-crystals to a solute and allowing it to cool out

36
Q

How can you form Acyl chlorides?

A

From carboxylic acid and SOCl2 (makes carboxyl-chloride and SO2 and HCl gas - so do it in a fume cupboard!)

38
Q

How can you reduce an aldehyde?

A

2[H] (from the NaBH4) and water, to produce a primary alcohol

39
Q

What is a zwitterion?

A

An ion with no overall charge, since the charges of the groups behaving as an acid and a base both cancel out (at the isoelectric point)

40
Q

What types of polymers can be made from condensation?

A

Polyesters and polyamides

41
Q

How can you identify a carboxyl group?

A

By reacting it with a carbonate (they are the only common organic compound sufficiently acidic to react), a positive test will show effervescence

42
Q

Why is phenol more reactive than benzene?

A

The lone pair of electrons from the p-orbital of the OH is donated into the pi-system and makes the ring more electron dense, increasing susceptibility to electrophile attack

42
Q

What is produced when an acyl chloride reacts with an alcohol?

A

An ester

43
Q

What effect(s) does the NH2 (anime) group have on the benzene ring?

A

It ‘activates’ it, allowing it to react more readily with electrophiles and also directing to positions 2 and 4 substitutions

43
Q

What is produced when an acyl chloride reacts with water?

A

A carboxylic acid

43
Q

How can you form an aromatic anime, from nitrobenzene?

A

6[H] and Sn + concentrated HCl and excess NaOH

44
Q

How can you determine melting point?

A

Melting point apparatus

Thiele tube

45
Q

How do you form a primary anime from a haloalkane?

A

Add excess NH3 then NaOH

46
Q

When phenol is nitrated (adding nitric acid), which 2 products are formed?

A

2-Nitrophenol and 4-Nitrophenol

48
Q

What is the (general) relationship between activating and deactivating groups?

A

All activating groups are 2 and 4 directing (except for halogens)
All deactivating groups are 3 directing

48
Q

What are the conditions and reagents required for the oxidation of an aldehyde, and what does it form?

A

Potassium dichromate and sulphuric acid, under reflux, to produce carboxylic acid

48
Q

How can you test for an aldehyde?

A

Add Tollen’s reagent, positive test forms silver mirror

49
Q

What is an optical Isomer?

A

Two versions of a molecule that cannot be superimposed, and are mirror images of one another

50
Q

What is produced when an acyl chloride reacts with a 1” amide?

A

A 2” amide

OCR Chemistry A for AS and A-Level (5 decks)

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