Unit 2 - Organic Chemistry Flashcards
What is a mechanism?
A mechanism shows the movement of electrons in a chemical reaction.
What does nucleophilic substitution produce?
Alcohols from haloalkanes, or amines from haloalkanes.
Give 2 examples of sources of hydroxide ions.
KOH and NaOH.
Give a source of CN (cyanide).
Potassium Cyanide.
Why is hydrogen cyanide (HCN) not a good source of cyanide.
It is extremely dangerous so it is far safer to use other sources.
What does elimination produce?
Alkenes from simple haloalkanes.
What are the conditions for elimination?
Heated under reflux.
How do we test between ketones and aldehydes?
Fehling’s solution: Ketone: No change to the blue solution (due to Fehling’s being a weak oxidising agent, hence no change with a ketone); Aldehyde: Brick-red precipitate of copper (I) oxide.
How do we distinguish between a tertiary and a primary/secondary alcohol?
Acidified Potassium Dichromate: Primary/Secondary: Orange to green; Tertairy: No visible change, solution remains orange.
What is the functional group of a carboxylic acid?
-COOH (with a double bond between the carbon and one of the oxygens).
Give the functional group of an aldehyde.
=O at the END of a carbon chain.
Give the functional group of a ketone.
=O somewhere in the middle of a carbon chain.
What do we call a C=O?
A carbonyl group.
What sort of alcohols can be oxidised under the conditions that we have?
Primary and secondary alcohols.
How do we acidify potassium dichromate?
We use concentrated sulphuric acid.
How do we test if we have an alcohol in a solution?
If an alcohol is present, it will react with phosphorus (V) chloride to produce a burst of steamy acidic HCl fumes.
How do we differentiate between an aldehyde and a ketone?
Fehling’s Solution or Tollen’s Reagent. With Fehling’s: Aldehyde: From blue solution, produces dark red precipitate of copper (I) oxide; Ketone: No visible change (blue solution remains blue). With Tollen’s: Aldehyde: Grey precipitate of silver forms in test tube (silver mirror); Ketone: No change in the colourless solution.
What is the functional group of an aldehyde, and how is one produced?
A C=O (and H) at the end of the carbon chain (remember like A is at the start of the alphabet, so the functional group of an Aldehyde is at the start (or end) of a chain).
An aldehyde is produced by partial oxidation of a primary alcohol using acidified potassium dichromate:
CH3CH2OH + [O] → CH3CH=O + H2O
(Note the O is double bonded to the C, not the H)
To prevent the aldehyde fully oxidising to make a carboxylic acid, we distil off the aldehyde as soon as it forms.
What is the functional group of a ketone and how is one produced?
A ketone has a C=O somewhere in the middle of a carbon chain.
They are made by an oxidation by acidified potassium dichromate of a secondary alcohol to form a ketone and water:
CH3CHOHCH3 + [O] → CH3COCH3 + H2O
