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Chem - A level (units 1 -10) > What's in a Medicine - Unit 5 > Flashcards

What's in a Medicine - Unit 5 Flashcards

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1
Q

What is some alchohols solubility with water?

A

Missible (mixable) with water

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2
Q

What alcohols are not missible with water and why?

A

1 - Ocatn-1-ol (long chain alcohols)

2 - Because lot’s of hydrogen bonds need breaking in the water

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3
Q

Describe the oxidation of a primary alcohol to carboxylic acid? (5)

A

1 - The oxidising agent, K2C2O7 / H+ is added to a primary alchohol

2 - The orange C2O72- is reduced to green Cr3+

3 - The OH group in the alcohol is converted into a C=O group

4 - The reaction mixture turns from orange to green

5 - An Aldehyde is produced which is then oxidised into a carboxylic acid in the presence of excess oxidisning agent

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4
Q

What are primar, secondary and tertiary alcohols oxidised to?

A

1 - Primary - Aldehydes –> carboxylic acids

2 - Secondary - Ketones

3 - Tertiary - Don’t oxidise

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5
Q

Describe the reaction conditions for the oxidation of secondary alcohols?

A

Heat under reflux in the presence of an oxidising agent

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6
Q

In the oxidation of secondary alcolhols, why is the ketone not oxidised further?

A

As not enough energy can be supplied to break covalent C-C bond

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7
Q

Why don’t tertiary alcohols oxidise?

A

because they don’t have a H atom on the C to which the OH group is attched

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8
Q

What is the final colour of the recation mixture in the oxidation of primary, secondary + tertiary alcohols?

A

1 - Primary -green

2 - Secondary - green

3 - Tertoary - orange - no oxidation

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9
Q

What is the suffix of ketones?

A

One e.g propanone

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10
Q

What is the suffix of aldehydes?

A

Al e.g ethanal

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11
Q

What are the reaction conditions for the dehydration of alchols to alkenes? (3)

A

1 - Industrially - 300oc + Al2O3 catalyst

3 - Lab - conc. sulfuric acid + heat under reflux

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12
Q

What is meant by an elimination reaction?

A

A reaction where a small molecule is removed from a larger molecule leaving an unsaturated molecule

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13
Q

What is dehydration an example of?

A

An elimination reaction

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14
Q

What conditions are needed for the nueclophillic substituion reaction of alcohols and what is produced? (4)

A

1 - Alcohols undergoe nucleophillic substition with halide ions

2 - In the presence of a strong acid

3 - Halolalkanes produced

4 - water is released

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15
Q

What are the two ways of converting alcohols into esters?

A

1 - Esterfication - Using an acid anhydride - React with alcohol or phenol to form ester

2 - Esterfication - Using a carboxylic acid - Only react with alchols to form ester

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16
Q

Describe the reation conditions for the esterfication of alcohols using caroxylic acid? (2)

A

1 - Small amount of conc. sulfuric acid/ conc. HCl

2 - Heated under reflux

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17
Q

In the esterification of alcohols using carboxylic acid, how is the ester collected? (2)

A

1 - Using distillation, ester is separted from mixture

2 - Ester then purified

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18
Q

How are esters named?

A

Ethanoate

  • Ethan- from ethanol
  • oate - from ethanoate
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19
Q

Describe the esterfication of alcohols using an anhydride? (2)

A

1 - React completely with an alcohol on warming

2 - Gives a higher yeild of ester than esterfication with carboxylic acid

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20
Q

What is this called Cr2O72-

A

dichromate (VI)

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21
Q

What compounds are part of the carbonyl group?

A

Any compound with C=O

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22
Q

What type of esterfication would you use and why? (3)

A

1 - Using acid anhydride

2 - Because it is faster

3 - Has a higher % yeild

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23
Q

How are ethers similar to alcohols?

A

structural isomers of alcohols

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24
Q

How are ethers different to alcohols?

A

Ethers more volatile than alcohols because they have no hydrogen bonding

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25
Q

How do carboxylic acids react with carbonates?

A

Form salt, water, CO2

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26
Q

How do carboxylic acids react with Na carbonates? (2)

A

1 - Sodium salt produced

2 - Fizzes as CO2 is released

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27
Q

What is a phenol?

A

OH group on a benzene ring (C6H5OH)

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28
Q

How do phenols compare with alcohols?

A

1 - Phenols are acidic whereas alcohols are not

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29
Q

What are the key features of phenols? (4)

A

1 - Turn Universal indicator paper red

2 - Don’t react with carbonates

3 - Are acidic

4 - Don’t form esters with alcohols or acids

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30
Q

How do you make esters from phenols? (2)

A

1 - Phenols do not react with carboxylic acids

2 - Therefore phenol + acid anhydride = ester

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31
Q

What is the test for phenols? (2)

A

1 - Add neurtal FeCl3 (aq)

2 - If phenol present then it will turn purple

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32
Q

What are the tests for carboxylic acids? (2)

A

1 - Added to aqeuous solution - turns it slightly acidic

2 - React with alcohols to produce esters - (have strong fruity/flower smells)

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33
Q

Whar are the three different environments that hydroxyl group can occur in? (3)

A

1 - In COOH group in carboxylic acids

2 - Attched to a benzene ring in phenols

3 - Attched to a alkane chain in alcohols

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34
Q

How does an OH group react with water?

A

A small no. of water molecules donate H+ ions to other water molecules, the water behaves as an acid

35
Q

How do OH groups reaction with water and phenols react?

A

Phenol + OH - The equilibirum lies further to the right than water as phenol is more acidic than water

36
Q

How do carboyxlic acids + phenols react with sodium hydroxide? (2)

A

1 - Forms sodium salts

2 - Form water

37
Q

What are alchols reactions with carbonates and hydroxyls?

A

They don’t

38
Q

What are the two ways of esterifying salicylci acid, products and features of products?

A

1 - The phenol group can react with an acid anhydride

  • Product = Aspirin
  • Soluble in water

2 - The COOH group can react with an alcohol

  • Product = methyl - 2 - hydroxybenzoate
  • Lipid soluble
39
Q

What is an aromatic compound?

A

has a benzene ring

40
Q

What is an Aliphatic compound?

A

carbon chains without benzene rings

41
Q

What is the structure for answering an exam Q on what the compound is from it’s Infared spectra?

A

1 - Strong absorbance at (wavenumber) which indicates (type bond) in an (compound)

2 - All this info can be taken from data sheet

42
Q

Why is mass spectrometry carried out in a vaccum?

A

So the ions have a free path and don’t collide with air molecules

43
Q

How do you produce a mass spectrum? (5)

A

1) Sample vaporised
2) High energy e- fired at the gas particles causing them to lose e- and become positive ions (ionisation)
3) The positive ions are accelerated by an electrical field

4) Time taken for positive ion to reach the detector is measured
- Light, highly charged ions take less time
Heavy, small charged ion take longer

5) A mass spectrum is then produced for the sample

44
Q

Describe infared spectroscopy? (2)

A

1 - Substances are exposed to radiation

2 - This makes vibrational energy chnages occur in the molecules, which absorb infared radiation of specific frequencies

45
Q

In an infared spectra, why are the frequncies absorbed different for each molecule? (2)

A

1 - Because the energy needed to excite a vibration depends on the bond strength

2 - Stronger bond = High frequency

46
Q

What does an infared spectrometer actually do?

A

Detects the absorbions and produces an infared spectra

47
Q

What determines the intesnity of an absorption?

A

More polar bond = more intense absorption

48
Q

What happens when simple diatomic molecules vs complex molecules absorb infared radiation? (2)(1)

A

Simple

1 - The atoms pull apart and then push together - stretching

2 - For these molecules there is only one vibrational infared absorbtion which corresponds to the molecules changing from a lower vibrational energy state to a higher vibrational energy state

More complex

1 - Have many vibrational modes - rocking, tiwsting etc

49
Q

What is the prupose of the fingerpirnt region in an Infared spectra?

A

For identification pruposes as is characteristic of that particular molecule e.g comparing it with another fingerprint region to see if the spectra is of the same compound

50
Q

What can mass spectroscopy be used for?

A

To find out the atomic mass of elements

To fidn out the relative abundances of isotopes in an element

51
Q

In mass spectroscopy, what is m/z equivilent to?

A

The molecular mass of the ion causing the peak

52
Q

Why is the m/z value for the molecular ion useful?

A

Helps chemists determine the molecular mass of the compound being analysed

53
Q

What is the fragmentation pattern?

A

The way in which a parent ion fragmets into smaller ions is characteristic of that compound

54
Q

What s the base peak?

A

The strongest detetcor signal of 100%

55
Q

What causes a peak at 1+ m/z of parent ion? (2)

A

Caused by the M+ ion with a C13 atom present in each ion being detected

56
Q

What is the size of the M+1 peak comapred to the peak caused by the molecualr ion?

A

The M+1 peak is smaller as there proportionally a smaller number of C13 atoms over C12

57
Q

What is the use of the fragmnetation pattern?

A

Allows you to identity which isomer the spectra belongs to as the fragments are characteristic of only one compound

58
Q

What can an absorption spectra be used for?

A

To decide which fucntional groups are present in an organic molecule

59
Q

What do the absorptions on an absorpion spectra represent?

A

They are characteristic of the bonds within the molecule

60
Q

Describe the steps in recrystalisation to purify an organic solid? (4)

A

1 - Dissolve organic solid in a minimum amount of hot solvent

2 - filter the solution to remove insoluble inpurities

3 - Allow to cool and crystalise

4 - Vacuum filter to remove soluble impurities - Wash crytsals with cold solvent and allow to dry

61
Q

What is the Mpt of an impure vs pure sample?

A

Pure - Sharp Mpt

Inpure - High range and Lower Mpt than pure sample as is a mixture

62
Q

What is a key point in recrystalisation?

A

Minimum amount of hot solvent is used

63
Q

What is an ideal feature of a solvent in recrytsalisation?

A

The organic solid dissolved in it readily when the solvent is hot

64
Q

How do you carry out Mpt determination? (5)

A

1 - Seal the end of a capillary tube using a bunsen flame

2 - Transfer small amount of sample onto a watch glass and press the open end of the tube onto the solid

3 - This will transfer some of the solid into the cappilary tube

4 - Flick tube to get solid to bottem and place in Mpt apparatus

5 - Record the temperature which it starts and fisnihes melting at to get a Mpt range

65
Q

When producing a product what are the key things you want? (4)

A

1 - High % yeild

2 - High atom economy

3 - Few number steps - more steps = less product

4 - How easily the product is purfied

66
Q

What happens in the stationary phase?

A

Something doens’t move

67
Q

What happens in the Mobile phase?

A

Something moves

68
Q

In Thin layer chromotography why is pencil use?

A

Ink would blur and move

69
Q

In TLC what is the stationary phase?

A

The plate

70
Q

In TLC what is the mobile phase?

A

The solvent/liquid

71
Q

Describe TLC chromotography? (8)

A

1 - Draw a pencil line 5mm from bottom of plate

2 - Dot the samples on seperate spots on the line

3 - Place plate in a beaker with solvent below the pencil line

4 - Put a lid on the beaker - stop solvent evaporating

5 - Allow solvent to travel up the plate, taking it out before it reaches the top

6 - Mark solvent front + dry plate

7 - Develop uisng I2 crystals or by U.V radiation

8 - Calulate Rf values

72
Q

What does similar R.F values mean?

A

The samples are the same compound

73
Q

How dou identify fragments with a lower mass? (2)

A

1 - They are usually due to small fragments of the hydrocarbon chain in the original molecule

74
Q

How do you identify fragments with larger masses?

A

1 - Look at the difference between the mass of this peak and the mass of the M+ peak

75
Q

What is the definition for the molecular ion?

A

An ion formed by the removal of an e- from a molecule without fragmentation of the molecular structure.

76
Q

In mass spectroscopy why are some peaks higher than others? (2)

A

1 - It’s the commonest fragment because:

  • There are sereval ways it can be produced
  • It’s the most stable ion

2 - This results in a higher peak

77
Q

What is green chemisrty?

A

Developing chemical products and processes that are environmentaly friendly and sustainable

78
Q

What are the 12 key pricniples of green chemisrty?

A

1 - Better atom economy - more product, less waste

2 - Prevention of waste products -

3 - Less hazardous chemical synthesis - use less hazardous reagants

4 - Design safer chemical products -

5 - Use safer solvents - minimise use of organic solvents

6 - Low energy usage - lower temp + pressure

7 - Use renewable feedstocks

8 - Reduce reagants used + no. steps

9 - Use catalysts + more selective catalysts - these reduce energy usage + waste

10 - Design chemical products for degradation - should break down

11 - Employ real time process monitoring - this reduces waste

12 - Use safer chemical processes

79
Q

What are some downfalls of the implemeting the 12 key pricnples of green chemistry? (3)

A

1 - Are less hazardous reagnts more expensive

2 - Is the new reagnat used to increase atom economy, more hazaroud

3 - Lower temp decrease reaction rate

80
Q

What can TLC be used for? (3)

A

1 - Seperate small quantities of organic compounds

2 - Check the purity of organic substances

3 - Follow the progress of a reaction over time

81
Q

How do you know whether a compound is pure is Mpt detrmination?

A

The compound should melt within 0.50c of it’s published true Mpt

82
Q

What is Mpt dtermination used for? (2)

A

1 - To measure how pure a sample is

2 - Help identiy a sample

83
Q

What’s a carbonyl compound?

A

Contains a O=

84
Q

What is meant by heating under reflux?

A

Liquid boiled, condensed and returned to flask

Chem - A level (units 1 -10) (14 decks)

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