Whats In A Medicine

Question 1

What are carboxylic acids?

Answer 1

Functional group= COOH
Made of a carbonyl group (C=O) and an OH group.
When naming the suffix -anoic acid is used eg a 4 carbon chain = butanoic acid

Question 2

What are esters?

Answer 2

Functional group= COO
Named after the alcohol and carboxylic acid from which they are formed.
eg butanol + ethanoic acid = butyl ethanoate

Question 3

What are aldehydes produced from?

Answer 3

The oxidation and distillation of primary alcohols

Question 4

What is the structure of an aldehyde?

Answer 4

They have a carbonyl group at the end of the carbon chain (carbonyl group is only attached to 1 other carbon atom) which gives them the functional group CHO.

Question 5

What is the structure of ketones?

Answer 5

Contain the functional group C=O.
They have a carbonyl group in the middle of the carbon chain (carbonyl group is attached to 2 other carbon atoms).

Question 6

How are ketones produced?

Answer 6

From the oxidation of secondary alcohols with acidified potassium dichromate (VI).

Question 7

What are acid anhydrides?

Answer 7

Functional group= COOCO which consists of 2 carbonyl groups joined by an oxygen atom.

Question 8

What are ethers?

Answer 8

Functional group=O
2 alkyl chains connected to a single oxygen atom.

Question 9

What is the functional group of an alcohol?

Answer 9

OH

Question 10

What is the general formula used for an alcohol?

Answer 10

CnH2n+1OH.

Question 11

Naming alcohols

Answer 11

Suffix= -ol

Question 12

What are phenols?

Answer 12

Organic compounds containing a benzene ring with a OH alcohol group thus making them aromatic alcohols. They act as weak acids.

Question 13

How can phenol be neutralised?

Answer 13

By reacting it with sodium hydroxide.

Question 14

Will phenol react with carbonates?

Answer 14

No

Question 15

What is the test for phenol?

Answer 15

Iron (III) chloride and if phenol is present a purple solution forms.

Question 16

What is esterification?

Answer 16

Carboxylic acids react with alcohols in the presence of a strong acid catalyst (eg sulphuric acid) to form esters. Carried out under reflux conditions.
-Remove the OH from the acid and the hydrogen from the alcohol to make water then join the acid and alcohol together!!!

Question 17

Describe the properties of an ester

Answer 17

Esters are sweet smelling compounds used in food flavourings and perfumes. They have low boiling points and are good solvents for polar molecules.

Question 18

Can acid anhydrides be used to esterify alcohols?

Answer 18

Yes… it occurs in an addition-elimination mechanism. Acid anhydrides react less vigorously then acrylic chlorides and do not produce toxic HCl as a side product. Therefore, they are often preferred as a reagent in esterification.

Question 19

Can tertiary alcohols be oxidised?

Answer 19

No

Question 20

What happens when primary alcohols are heated with potassium dichromate (VI)?

Answer 20

They are oxidised to aldehydes. Distillation is required to separate the aldehyde product.

When an aldehyde is heated further with acidified potassium dichromate (VI) under reflux conditions, the aldehyde is oxidised to a carboxylic acid.

ALCOHOLS-> ALDEHYDES -> CARBOXYLIC ACIDS

Question 21

What happens when acidified potassium dichromate (VI) reacts with secondary alcohols?

Answer 21

They are oxidised to ketones.

Question 22

What is potassium dichromate?

Answer 22

Used as an oxidising agent in the oxidation of alcohols. As the alcohol is oxidised, potassium dichromate is reduced. Reduction is observed by a colour change from orange to green which indicates the alcohol has undergone oxidation. Colour change is due to change of oxidation state of the chromium ion.

Question 23

What is an elimination reaction?

Answer 23

A small molecule is removed from a larger molecule, often forming a double bond.

Question 24

How can you form alkenes?

Answer 24

From the dehydration of alcohols, where a molecule of water is removed from the molecule. The alcohol has to be heated under reflux with conc sulphuric acid or heated using Al2O3.

Question 25

What is nucleophilic substitution?

Answer 25

Allows alcohols to react with halogenating agents. The OH group of the alcohol is replaced by a halogen producing a haloalkane.

Eg Potassium bromide reacts with sulphuric acid to form HBr which then reacts with the alcohol to form a bromoalkane.

Question 26

What is recrystallisation?

Answer 26

A method of purifying an impure compound using a solvent. This method relies on the fact that the solubility of most organic solids increases with temperature. An impure solid is dissolved in the MINIMUM amount of hot solvent, as the solution is cooled the solubility of the solid decreases and crystals will form.

Question 27

Thin-layer chromatography (TLC)

Answer 27

A metal plate is coated with a thin layer of silica and the sample being analysed is dotted on the plate. These samples must be placed above the level of the solvent in the container.
Solvent is allowed to move up the plate, separating the substances within the sample. Plate is taken out the container and the solvent front is marked in pencil which is the distance the solvent has travelled.
Plate is dried in a fume cupboard to reduce toxic fumes. Chemical traces can be viewed using a UV lamp and distances travelled by substances can be measured. A developing agent can be added such as iodine to allow the colourless traces to be seen by the naked eye.

Question 28

What is heating under reflux?

Answer 28

Continually heats the flask to allow reaction such as oxidation of primary alcohols to proceed to formation of carboxylic acids. Condenser ensures vapours condense and return to flask for further heatings product vapours do not escape.

Question 29

What is distillation?

Answer 29

Seperates liquids with different boiling points. The round-bottomed flask is heated and the liquid with the lower boiling point will evaporate first. It rises out the flask into the attached tubing surrounded by a condenser which causes thee vapour to condense back into a liquid collected in a different flask.