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Chemistry A2 > Organic > Flashcards

Organic Flashcards

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1
Q

Define chiral carbon

A

A carbon atom that is bonded to 4 different groups, tetrahedrally arranged

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2
Q

How many hydrogen atoms are bonded to 1 carbon atom in a benzene ring

A

1

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3
Q

Define optical isomer

A

Molecules that contain chiral carbons so that the two enantiomers are non-superimposable mirror images

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4
Q

What is used to measure the rotation of polarised light?

What is it called if the light:
Rotates right?
Rotates left?

A

Polarimeter

Dextrorotatory

Levorotatory

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5
Q

Define racemic mixture

A

A mixture containing equal amounts of two enantiomers which produce equal but opposite rotation of polarised light so no overall rotation is observed

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6
Q

Why is the product formed from the nucleophilic addition of cyanide a racemic mixture?

A

Because the cyanide ion is equally likely to attack the carbon atom from the left or the right
And the carbonyl group is planar

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7
Q

Tests for aldehydes or ketones

A

Tollens reagent
Silver mirror when warmed with aldehyde
Ketone remains colourless

Fehlings solution
Brick red precipitate formed with aldehyde
Remains blue with ketone

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8
Q

What is the reducing agent in the nucleophilic addition reaction with a COOH or Aldehyde or ketone?

What is a stronger reducing agent than this one?

A

NaBH4 in aqueous solution

liAlH4

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9
Q

Outline the 2 stage nucleophilic addition reaction of a COOH

What type of alcohol does NaBH4 reduce
An aldehyde into?
A ketone into?

A

CH3COOH + 2[H] > CH3CHO + H2O

CH3CHO + 2[H] > CH3CH2OH

1 degree OH
2 degree OH

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10
Q

How is an ester named?

A

Ethyl methanoate

Ethyl is from OH
Methanoate is from COOH

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11
Q

What is the reaction for esterification?

What type of reaction is an esterification reaction?

A

OH + COOH > ester + H2O
H+
Reflux

Reversible reaction
Conc H2SO4 homogenous acid catalyst

Condensation reaction

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12
Q

Define homogenous catalyst

A

A catalyst which is in the same physical state as the reactants

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13
Q

What is the disadvantage of esterification?

A

It is a reversible reaction is a low yield is produced

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14
Q

What are the properties of an ester?

A

Volatile (evaporates easily) - produces sweet smell

No hydrogen bonds - lower b.p than reactants and is insoluble in water

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15
Q

Test for OH/COOH using esters

A

Esterification reaction - if fruity smell, OH/COOH is present

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16
Q

The reaction for the acid hydrolysis of an ester

Why must NaOH be in excess

A 
Ester + water > OH + COOH
                       H+ reflux
                       conc H2SO4 
                       Or NaOH as catalyst 
Reversible reaction

To prevent formation of salt with COOH

17
Q

The reaction for base hydrolysis of an ester

What happens to the reactant as a result of the base?

A

ester + OH- > carboxylate ion- + OH

Carboxylate ion- bonds with Na+ to form salt
I.e sodium ethanoate

18
Q

What’s another name for glycerol?

A

Propan-1,2,3-triol

19
Q

How are veg oils and animal fats produced?

Define saturated. What is the effect of this on the melting point?

Define unsaturated. What is the effect of this on the melting point?

Which product is saturated and which product is unsaturated?

A

Esterification of glycerol to produce a triester (which are the animal fats and veg oils)

Single bonds between carbon atoms
Lower SA, more VDW forces = higher m.p

Double bonds between carbon atoms
Lower SA, less VDW forces = lower m.p

Fats are saturated, oils are unsaturated

20
Q

What is the reaction for the hydrolysis of fats and oils?

A 
Triester + 3NaOH > glycerol + 3RCOO-Na+
Sodium salt (soap) produced
21
Q

Reaction for the conversion of soap back into free fatty acids

A 
RCOO-Na+ + H+ > RCOOH + Na+
                        Strong acid(I.e HCl)
22
Q

What are the uses of esters?

A

Sweet smell and taste = perfumes and food flavouring
They are Polar molecules = polar organic solvents dissolve in them
Low b.p = volatile so good glue solvents
Flexible = used as plasticisers for polymers, which is added during polymerisation

23
Q

What is a disadvantage of a plasticiser?

A

Plasticiser molecules escape over time so the polymer becomes brittle and stiff

24
Q

What is a different way of drawing a benzene ring?

A

With alternating carbon carbon double bonds

25
Q

Why are benzene rings very stable

Long explanation

A

Each carbon atom is bonded to only 1 hydrogen atom
So there is a lone electron on each carbon atom
These lone delocalised electrons are in the p orbital
All the p-orbitals combine to make a ring of electrons above and below the structure
Electron density is shared across the entire structure

26
Q

What is the order of bond lengths between carbon atoms?

A

C=C 135pm
Benzene 140pm
C-C 147pm

27
Q

Define electrophile

A

A species that accepts a pair of electrons

28
Q

What property of an electrophile makes it suitable for reactions with benzene? Why is it suitable?

A

It is very reactive

Which is required because benzene is so stable

29
Q

Outline the 2 step reaction for the production of a nitronium ion

Why can this reaction occur?

A

H2SO4 + HNO3 > HSO4- + H2NO3+
H2NO3+ > NO2+ + H20

Because HNO3 acts as a base because it is less reactive than H2SO4

30
Q

What is produced as a result of the electrophilic substitution of a nitronium ion

A

Nitrobenzene and a hydrogen ion

31
Q

What is the final reaction step in the nitration of benzene?

A

Reformation of catalyst

H+ + HSO4- > H2SO4

32
Q

What are the uses of nitrobenzene?

A

Nitro compounds decompose violently when heated - explosives
Nitrobenzene can be converted to phenylamine which can be used for dyes

33
Q

Outline the reaction of the formation of an acyl carbocation?

What is the catalyst of this reaction known as?

This is the first step of what reaction?

A

AlCl3 + RCOCl > AlCl4- + RCO+

Halogen carrier catalyst

Friedel-crafts Acylation

34
Q

What is produced in the electrophilic substitution of an acyl carbocation?

What are the conditions of this reaction?

A

Phenylketone + HCl +AlCl3

Reflux
AlCl3 catalyst

Chemistry A2 (8 decks)

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