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LAST MINUTE CHEM > Final deck part 2 ennit > Flashcards

Final deck part 2 ennit Flashcards

1
Q

Homologous series?

A

Organic compounds which have the same functional group and general formula
Each member differs by CH2

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2
Q

What’s an aromatic compound?

A

Contain a Benzene ring

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3
Q

What’s an aliphatic compound?

A

Contains Carbon and Hydrogen bonded together in straight lines, branched chains, or non aromatic rings

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4
Q

What can you call an alpiphatic chain with a non aromatic ring?

A

Alicyclic

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5
Q

What’s an isomer?

A

When 2 molecules have the same molecular formula, but the atoms are arranged differently

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6
Q

What are the 2 types of isomers?

A

Structural isomers and stereoisomers

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7
Q

What are the 3 types of structural isomers?

A

Chain
Positional
Functional group

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8
Q

What’s a chain isomer?

A

Carbon skeleton can be arranged differently, straight or branched

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9
Q

What’s a positional isomer?

A

Carbon skeleton and functional group the same, except functional group bonded at a different carbon

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10
Q

What’s a functional group isomer?

A

The same atoms can be arranged into different functional groups

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11
Q

What’s heterolytic bond fission?

A 
Bond breaks unevenly, with one of the bonded pairs receiving both electrons
A cation (+) and an anion (-) are formed
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12
Q

What’s homolytic fission?

A

Bond breaks evenly, and each bonding pair receives an electron
Two neutral radicals are formed ( have an unpaired electron)

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13
Q

What occurs in initiation stage?

A

Free radicals are produced
Cl2 = (UV light) 2Cl# = photodissocation
So has been split homolytically
#= radical symbol

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14
Q

What occurs in propagation stage?

A 
Cl# + CH4 = #CH3 + HCl
#CH3 + Cl2 = CH3Cl + Cl#
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15
Q

Termination reactions?

A 
Cl# + #CH3 = CH3Cl
Cl# +Cl# = Cl2
#CH3 + #CH3 = C2H6
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16
Q

What’s a sigma bond?

A

Forms when 2 s orbitals overlap in a straight line, this gives the highest possible electron density between the 2 nuclei, this is a single covalent bond
The high electron density between the nuclei means there is a strong electrostatic attraction between the nuclei and shared pair of electrons

Strongest type of covalent bond

Draw these by having 2 spheres with a dot in the middle for a nucleus, and draw them overlapping in a diablo shape

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17
Q

What’s a pi bond?

A

Formed from the sideways overlap of 2 adjacent p orbitals
It’s bellow and above the molecular axis, because the pi orbitals that overlap are dumbbell shaped
Pi bonds are weaker than sigma bonds because electron density spread above and bellow the nuclei, so weaker electro static attraction between nuclei and shared pair of electrons, so break easier than sigma bonds

Draw this by having 2 dumbell shapes with curved lines connecting each top of the dumbell

Which forms 2 dots with a curved pi bond above and bellow

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18
Q

When does stereoisomerism occur?

A

When the two double bonded carbon atoms have each have 2 different atoms or groups bonded to them

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19
Q

What’s a Z isomer?

A

When the same atom/group with the priority are both above or both bellow on each side

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20
Q

What’s an E isomer?

A

When the same atom/group with the priority are on diagonal sides

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21
Q

What’s a cis isomer?

A

If the same groups are on the same side on each side of the C=C bond (don’t have to be priority)

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22
Q

What’s a trans isomer?

A

If the same groups are on different sides of the C=C bond (don’t have to be priority)

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23
Q

How do you produce an Alkane from an Alkene?

A

Add hydrogen gas

Ni catalyst and temperature around 150 degrees

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24
Q

What’s the mechanism of halogens being reacting with alkenes to form dihaloalkanes?

A

Draw the alkene eg ethane, and draw the halogen eg bromine molecule near the double bond, the closer bromine atom will have a delta positive charge, as electrons have been repelled away by double bond, making the other Br molecule delta negative

Draw curly arrow from double bond to Delta + Br
Draw curly arrow from bond between Br’s to the delta negative Br

Draw the double bond now split to a single bond, and one C has a Br molecule attached, the other C will have a positive charge, and draw the other Br molecule with a negative charge and a lone pair with a curly arrow to the positively charged carbon

Draw the final dihaloalkane

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25
Q

How do you make ethanol from Ethene?

A

Add water as steam at 300 degrees
60-70 atm
Phosphoric acid catalyst

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26
Q

How do you produce a haloalkane from an alkene?

A

Add a hydrogen halide

It’s an addition reaction

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27
Q

when a hydrogen halide reacts with an unsymmetrical alkene how do you know which is the major and minor product?

A

Major product is more stable so the halide ion will bind to the Carbon which is bonded directly to the most other Hydrogens( least amount of carbons)

Minor product is less stable, so the halide ion will bind to the Carbon which is bonded directly to less hydrogens(more amount of Carbons)

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28
Q

How would you draw a pi and sigma bond together?

A 
Have the carbon atoms with a spherical Sigma bond between them (hot dog)
Have the (bun) pi bonds above them, with 2 hydrogen s coming of each Carbon
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29
Q

what can OH be swapped for to produce a Haloalkane, and what catalyst is required?

A

halogen in a substitution reaction

acid catalyst

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30
Q

what can be done to alcohols to form alekenes?

A

can be dehydrated, in a elimiation reaction

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31
Q

Whats the reaction mechanism for nucleophillic substitution reaction?

A

Draw the halolkane with a delta positve charge on Carbon, and delta negative on halogen

draw an OH- ion with a lone pair near it, and a curly arrow going from lone pair to the delta positive carbon

this forms an alcohol and the halogen forms with a lone pair and a negative charge

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32
Q

How can you show that iodalkanes have the weakest bonds (due to largest atomic radius) and Chlorine have the strongest?

A

react R-Cl, R-Br and R-I each with silver nitrate solution (prvides silver ions), and ethanol as a solvent

white percipitate will forms slowest

yellow preciptate will form fastest

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33
Q

How is Ozone formed?

A

O2 = 2O# radicals due to UV light

O2 + O# = O3

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34
Q

How do CFC’s destroy the Ozone?

A

Chlorine free radicals are formed when the Cl-Cl bonds in CFC’s are broken down by UV light
eg. CF2Cl2 = (UV) CF2Cl + Cl#
Then Cl# + O3 = O2 + ClO#
ClO# + O = O2 + Cl#

So overall reaction is O3 + O = 2O2 and Cl# is the catalyst

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35
Q

Equations for NO# breaking down ozone?

A

NO# + O3 = NO2 + O2

NO2 + O = NO# + O2

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36
Q

What is special about the OH peak in a carboxylic acid?

A

Much broader

37
Q

How can a mass spectrum be used to identify compounds?

A

The molecules in the sample are bombarded with electrons to form a molecular ion, M+(g)
Can create graph with relative abundance on y axis, and mass/charge on x axis
To find the relative mass of a compound find the molecular ion peak which will be value furthest up the x axis
(Be careful of M+1 peak, which is formed by presence of Carbon isotope C13)

38
Q

How can the molecular ion be broken into smaller fragments and what can you tell from this?

A

Bombrading of electrons causes some molecular ions to split
The molecular ion can split in 2 ways show 2 different molecular ions can form
However if one forms then other one is going to be a free radical and is “lost”

39
Q

What’s different with addition reactions with benzene rather than alkenes?

A

For it to work with Benzene require hot Benzene and ultraviolet light, as Benzene is far more stable due to delocalised electrons

40
Q

Equation for Haloalkane with a halogen carrier?

A

R(delta +) - Cl(delta -) + AlCl3 = R+ (carbocation) + AlCl4 -

41
Q

How would you draw Bromine reacting with Benzene with aid of AlCl3 catalyst?

A

Draw the bromine molecule with one end delta + and one delta -
Draw Benzene
Write AlCl3
Have a curly arrow going from Br-Br bond to AlCl3, and a curly arrow from the delocalised electrons from ring to delta + Br
This produces benzene ring where delocalised ring as hole in it, is positively charged and has Br and a H visibly bonded to it
Also produces AlCl3Br-
Finally forms Bromobenzene + HBr + AlCl3

42
Q

General formula for an alkylation Fridel craft reaction?

A

C6H6 + R-X =(AlCl3 catalyst + reflux) C6H5R + HX

R= alkane part of halogen
X= Halogen
43
Q

General formula for an acylation reaction?

A

C6H6 + RCOCl = ( AlCl3 catalsyt + Relfux) C6H5COR + HCl

COR = Carbon doubled bonded to Oxygen, then bonded to a Carbon Chain (R)

44
Q

How does Nitric Acid act as an Electrophile with a sulfuric acid catalsyt?

A

Nitronium ion is formed
HNO3 + H2SO4 = H2NO3+ + HSO4-
H2NO3+ = NO2+ +H2O

45
Q

How to draw Nitric acid reacting with Benzene with a sulfuric acid catalyst?

A

Benzene ring with curly Arrow going to NO2 + (nitronium ion)
Delocalised ring broken, Benzene also has + charge
NO2 and H bonded to ring
Nitrobenzene formed, H+ ion reacts with HSO4 - to reform the catalyst

46
Q

How do functional groups affect the position of substitution?

A

In an unsubstituted ring all Carbons just as likely as e- density the same everywhere

Electron donating groups (OH and NH2), direct substiution to Carbons 2, 4 and 6, as orbitals overlap increasing the e- density specifically at these Carbons

Electron withdrawing groups (NO2) direct substiution to Carbons 3 and 5, has no overlapping orbitals and it’s electronegative so withdraws e- density from ring, most specifically on carbons 2, 4 and 6

47
Q

What do you get if you react phenol with Bromine water?

A

2,4,6-tribromophenol is formed aswell as 3HBr

Bromine water is decoulourised
Insoluble in water and precipitates out of the mixture, smells of antiseptic

48
Q

What’s produced when Phenol is Nitrated with Dilute Nitric acid?

A

2-nitrophenol or 4-nitrophenol and water

49
Q

What happens if you react Phenol with NaOH?

A

Sodium phenoxide (benezene ring bonded to O- which is bonded to Na+) is formed and water

50
Q

Describe the reaction mechanism of the reducing agent NaBH4, dissolved in water with methanol reducing an aldehyde to a primary alcohol, or a Ketone to a secondary alcohol and what type of reaction is it?

A

It’s a nucleophillic addition reaction

NaBH4 provides a H- ion with a lone pair, the carbonyls groups carbon will have a delta positive charge, and the oxygen will have a delta negative charge

H- ion will have a curly arrow going from the lone pair to the delta + carbon, and there will be a curly arrow going from the double bond in the carbonyl group to the delta negative oxygen

This will form a carbon bonded to the 2 other original elements, a hydrogen and a single bonded to a negative oxygen with a lone pair

Now draw a water molecule, with 2 delta positive hydrogens, and a delta negative oxygen

Draw a curly arrow going from lone pair on oxygen to a delta positive hydrogen, and a curly arrow going from the bond between the delta postive hydrogen, and the delta negative oxygen to the oxygen

This will form an OH- ion, and either a primary or secondary alcohol

51
Q

Describe how hydrogen cyanide will react with aldehydes or ketones to form hydroxynitriles and what type of reaction is it?

A

Nucleophillic reaction

Hydrogen cyanide is a weak acid so HCN will dissociate into H+ and CN- ions

Draw N triple bonded to C(-) and draw the aldehyde or ketone with a delta negative oxygen double bonded to the delta positive carbon

Draw a curly arrow going from the lone pair on Carbon to the delta positive carbon, and also a curly arrow from the double bond in the carbonyl group, to the delta negative oxygen

This will form a carbon bonded to it’s 2 original elements, a carbon triple bonded to a Nitrogen, and single bonded to an oxygen with a lone pair and a negative charge.

The lone pair on the oxygen will have a curly arrow going to the H+ remaining from the dissociation of the hydrogen cyanide, making it so the carbon is now bonded to an OH group, which is the hydroxynitrile

52
Q

How do you test for Aldehydes and Ketones, and also which specific one is?

A

When 2-4 DNP (brady’s reagent) is dissolved in methanol and sulfuric acid, it will react with carbonyl groups to form a bright orange precipitate

Can then determine then melting point of the orange precipitate and compare it to a database to find which exact carbonyl compound it is

53
Q

How do you test for aldehydes only?

A

Heat test substance with tollens reagent, in water bath (silver nitrate dissolved in aqueous ammonia)

If present aldehyde present it will be oxidised, and silver ions are reduced to form a silver mirror

54
Q

What is an acyl chloride, and how do you name them?

A

Same as carboxylic acid, except replace the OH group with a Cl, name them by putting at the end “oyl chloride”

55
Q

How do you make an acyl chloride?

A

React a carboxylic acid with SOCl2, to produce an acyl chloride, SO2 and HCl

56
Q

What happens when acyl chlorides react with cold water?

A

Produce a carboxylic acid and HCl

57
Q

What happens when acyl chlorides react with alcohols?

A

Produce an ester and HCl

58
Q

What happens when acyl chlorides react with Ammonia?

A

Primary amide and HCl

59
Q

What happens when acyl chlorides react with amines?

A

Secondary amide and HCl

60
Q

What type of reaction are all the reaction with acyl chloride?

A

Nucleophillic addition-elimination

All reactions are with the chlorine

61
Q

What happens when acyl chlorides react with phenol?

A

An ester and HCl

Reversible reaction

62
Q

How do you make an ester and water from alcohols and carboxylic acids?

A

Heat them together in the presence of sulfuric acid catalyst

It’s an esterfication reaction

Reversible reaction, so need to heat under reflux and use fractional distillation to separate the ester from other compounds

63
Q

How do you name an ester?

A

Look at the alkyl group that came from the alcohol (the bit single bonded to the oxygen) and add yl to end of it, eg ethane = ethyl

Look at bit from carboxylic acid (bit bonded to the carbon double bonded to the oxygen (include that carbon aswel)) and find the name of it and replace oic acid with oate, eg ethanoic acid = ethanoate

Put the 2 parts together, eg = ethyl ethanoate

64
Q

2 ways esters are hydrolysed to form alcohols?

A

Acid hydrolysis:
Reflux the ester with sulfuric acid, and H2O, will produce a carboxylic acid and an alcohol

Base hydrolysis:
Reflux the ester with NaOH, to get a carboxylate salt (instead of H in OH group of carboxylic acid, it’s a Na) and an alcohol

65
Q

What’s an amine?

A

If or more of the hydrogens in ammonia are replaced by an organic group

66
Q

How can you make aliphatic amines, and the second step you have to do aswell?

A

Heating a haloalkane with an excess of ammonia dissolved in ethanol

Will produce a mixture of primary, secondary, tertiary amines, and quaternary ammonium salts, as more than one hydrogen is likely to undergo nucleophillic substiution

So have to separate products using fractional distilation

67
Q

How can you make aromatic amines?

A

Heat a mixture of a nitro compound, tin metal, and concentrated HCl under reflux which creates a salt

To get the aromatic amine, have to then add NaOH

68
Q

What’s an amide?

A

Carboxylic acid derivative

So it’s a C double bonded to an oxygen, and single bonded to a Nitrogen which is bonded to 2 hydrogens

Becomes a secondary amide if one of the hydrogens bonded to the nitrogen is an organic group

69
Q

Optical isomers are optically active, what does this mean?

A

They rotate plane-polarised light, one optical isomers rotates it in a clockwise direction, the other rotates it the same amount, but in an anticlockwise direction

70
Q

2 types of condensation polymer, and what bond links the 2 monomers together?

A

Polyester (-COO-), an ester link

Polyamide (-CONH-) an amide link

71
Q

How are the condensation polymers broken down and what needs to added to a polymamide, and what needs to be added to a polyester?

A

Hydrolysis, water molecules are added to break the bonds.

In practice far too slow, so add an acid for a polyamide, and a base for a polyester

72
Q

What do you react to create a polyamide?

A

A dicarboxylic acid (COOH group at both ends) and a diamine (NH2 group at both ends)

73
Q

What do you react to create a polyester?

A

A dicarboxylic acid (COOH group at both ends) and a diol (OH group at both ends)

74
Q

Describe the reaction mechanism of Cyanide ions reacting with haloalkanes via nucleophillic substitution and the reaction mechanism to extend the carbon chain?

A

Conditions are ethanol and reflux

Draw the haloalkane, with a delta positive charge on the carbon bonded to the halogen, and a delta negative on the halogen. Have the C-(lone pair)(triple bonded to)N by the side

Draw a curly arrow from the bond between the carbon and the halogen to the halogen forming a negative ion. And have a curly arrow from the C- to the delta positive C

Forming the alkane now bonded to another C which is triple bonded to a N (THIS IS A NITRILE), and a halogen ion

75
Q

Describe the nucleophillic addition reaction mechanism of Carbonyl compounds with Hydrogen Cyanide to extend the carbon chain?

A

Draw the carbonyl compound with a delta positive carbon double bonded to a delta negative Oxygen. And draw the cyanide ion (C-(lone pair) triple bonded to N)

Draw a curly arrow from the double bond in the carbonyl group to the delta negative oxygen, and draw a curly arrow from the lone pair on the carbon to the delta positive carbon

This will form the carbon in the carbonyl compound single bonded to an O- and bonded to another carob which is triple bonded to a Nitrogen

The H+ ion will then react with the O- to form an OH group

A HYDROXYNITRILE IS FORMED, the carbon from the carbonyl group is now single bonded to an OH group and single bonded to a carbon which is triple bonded to a nitrogen

76
Q

What can you add to Nitriles or Hydroxynitriles to reduce them to primary amines?

A

Lithium Aluminium hydride (LiAlH4)
Dilute acid

Or Sodium metal and ethanol

77
Q

How are nitriles or hydroxynitriles reduced to primary amines industrially as Sodium and LiAlH4 are too expensive?

A

Catalytic hydrodgenation

Hydrogen gas with a nickel catalyst at high temp and pressure

78
Q

How do you get an aldehyde, and then a carboxylic from a primary alcohol?

A

For an aldehyde (apple smelling), gently heat a primary alcohol with potassium dichromate solution and sulfuric acid in a distillation apparatus, so aldehyde is immediately distilled off. Colour change of orange to green

For a carboxylic acid (vinegar smell), vigorously heat a primary alcohol with potassium dichromate solution and sulfuric acid under reflux. Colour change of orange to green

79
Q

How do you get a ketone from a secondary alcohol?

A

Reflux and heat secondary alcohol with pottassium dichromate solution, and sulfuric acid to produce a ketone. Colour change from orange to green

80
Q

How can you remove any water soluble impurities from a compound?

A

Use separation, if the product is insoluble and want to remove any impurities that do dissolve in water

Once the reaction is complete, the mixture is poured into a separating funnel, and water is added

The funnel is shaken and then allowed to settle, the organic layer is less dense that the aqueous layer so should float on top

Any water soluble impurities should have dissolved in the lower aqueous layer, so can run off funnel into only left with the organic layer

The organic layer will now contain trace amounts of water, so it has to be dried

Add an anhydrous salt such as magnesium sulphate, which will act as a drying agent

Then filter the product to remove the solid drying agent

81
Q

Describe how organic solids can be purified by recrystallisation?

A

Very hot solvent is added to the impure solid, until it just dissolves

This provides a saturated solution ( maximum amount of solid dissolved)

The solution is left to cool down slowly. Crystals of the product form as it cools, the impurities stay in solution, as they are in much smaller quantities so they take much longer to crystalise out

The crystals are removed via filtration under reduced pressure and washed with ice cold solvent

They are dried, leaving with you product much cooler than the orginal

82
Q

Describe how the melting point and boiling point will differ the more impure a substance is?

A

The melting point is lowered more

The boiling point increases

83
Q

How do you test for phenols?

A

First add sodium hydroxide as its a strong base to test for weak acid nature of phenols

So if the solid dissolves and a colourless solution of a sodium salt forms, then it’s acidic

Then add sodium carbonate to test that it’s a strong acid and not a weak acid, as it will only react with a strong acid

So now if there’s no effervescene then our susbtance but be phenol as it’s a weak acid

84
Q

How do you test for carboxylic acids?

A

Add sodium carbonate, The solution will fizz, the CO2 gas produced will turn limewater cloudy

85
Q

Describe the basics of how NMR spectroscopy works?

A

A sample of a compound is placed in a strong magnetic field and exposed to a different range of frequencies of radio waves

The nuclei of certain atoms within the molecule absorb energy from the radio waves

The amount of energy that a nucleus absorbs at each frequency will depend on the environment that it’s in

The pattern of these absorptions gives you information about the posistion of certain atom within the molecule,, and how many there are in within the molecule.

So can work out it’s structure

86
Q

What does a peak represent on a Carbon 13 NMR spectrum?

A

A carbon environment, so the amount of peaks = the amount of environments

87
Q

Why is tetramethylsilane (Si(CH3)4) used as a standard for NMR (it’s value is 0)?

A

It produces a single absorption peak in both types of NMR because all it’s carbon and Hydrogen nuclei are in the same environment

It’s absorption peak is lower than everything else

88
Q

What’s the number of neighbouring hydrogens if the peak is split into a doublet (2 peaks) a triplet (3 peaks) or a quartet (4 peaks)?

A

N + 1 rule

Doublet = one hydrogen on the neighbouring carbon
Triplet = 2 hydrogens on the neighbouring carbon
Quartet = 3 hydrogens on the neighbouring carbon
89
Q

How can OH and NH protons be indentified by proton exchange using D2O?

A

The chemical shift produced by protons attached to O or N is very variable

Run 2 spectra of the molecule, one with Dueterium oxide added (D2O)

If an OH or NH proton is present, it will swap with deuterium and the peak will dissapear as deuterium dosen’t aborb the radiowave

Can compare spectra and work which ones are the NH and OH peaks

LAST MINUTE CHEM (4 decks)

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