26.1- 26.4 Flashcards
What are carbonyls
- compounds with the C=O functional group like aldehydes and ketones
What is the difference between aldehydes and ketones
- the position of the C=O group
Where is the C=O group on aldehydes
- at the end
- prefix= -al
Where is the C=O group on ketones
- in the inner/middle carbon
- ending= -one
What are aldehydes oxidised to
- carboxylic acids
Reagent: K2Cr2O7
Catalyst: H2SO4
What are ketones oxidised too
- nothing, they can’t be oxidised
What do we use Tollen’s reagent for
- to distinguish between aldehydes and ketones
What is Tollen’s reagent made of
- silver nitrate solution
- few drops of NaOH
- few drops of dilute ammonia
Why do we use a a hot water bath for the reaction Tollen’s reagent with aldehydes and ketones and not a Bunsen burner
- as aldehydes and ketones are flammable
If an aldehyde is present in Tollen’s reagent what do we get
- a silver mirror is produced
If an ketone is present in Tollen’s reagent what do we get
- nothing
How do we test for carbonyls and what do we see for positive results
- using 2,4 DNP
- if a carbonyl groups exists a yellow-orange precipice is formed
- you can dry the precipitate and recrystallise it and find its melting point and compare it to know melting points to see if its an aldehyde or ketone
When aldehydes are reduced what do they form and what reagent is used
- primary alcohols
- Reagnent: NaBH4
When ketone are reduced what do they form and what reagent is used
- secondary alcohols
- Reagent: NaBH4
What reactions do carbonyls undergo
- nucleophilic addition
What do potassium cyanide compound reacts with carbonyls to make in nucleophilic addition
- hydroxynitrile ( molecules contains OH and CN groups)
What are the risks when using potassium cyanide
- KCN is an irritant very dangerous if ingested or inhaled
- KCN reacts with moisture it can form a toxic gas, hydrogen cyanide
How do we reduce the risks of KCN
- wear a lab coat
- wear safety goggles at all times
- use a fume cupboard to prevent exposure to toxic fumes
- wear gloves while handling
What is the functional group of carboxylic acids
-COOH
- contains both carbonyl group (C=O) and a hydroxyl group (OH)
- ending -oic acid
What is the solubility of carboxylic acids and why
- can dissolve in polar solvents like water
- because they can hydrogen bond with water molecules
What does the bigger the hydrocarbon part in a carboxylic acids mean
- as the hydrocarbon is non-polar it will decrease the carboxylic acid
What type of acids are carboxylic acids
- weak acids-> partially dissociates
- equilibrium favours the backwards reaction so leis on the left
When carboxylic acids react with carbonates what do they produce
- salt, carbon dioxide and water
What do carboxylic acids form when they react with alkalis
- salt and water
What do carboxylic acids form when they react with metal oxides
- salt and water
What do carboxylic acids form when they react with metal and what will you be able to observe
- salt and water
- can observe bubbling from the hydrogen
What are the derivates of carboxylic acids
1) acyl chlorides
2) acid anhydrides
What is the functional group of acyl chlorides
-COCl
What is the prefix of acyl chlorides
-oyl chloride
How are acyl chlorides made and what other products are made
- by reacting carboxylic acids with thinoyl chloride (SOCl2)
- other products: SO2 and HCl
What 4 things do acyl chlorides react with and in each of these reactions what happens
- they react with:
1) water
2) ammonia
3) alcohols
4) primary amines
-in each reaction Cl is substituted for either oxygen or nitrogen
What are the products of this reaction:
Ethanoyl chloride + water
And what is this reaction called
- ethanoic acid (carboxylic acids)
- HCl (produces white misty fumes)
Called: NUCLEOPHILIC- ADDITION ELIMINATION
What are the products of this reaction:
Ethanoyl chloride + ammonia
And what is this reaction called
- ethanamide (amide)
- HCl (white misty fumes produced)
Called: NUCLEOPHILIC ADDITION- ELIMINATION reaction
What are the products of this reaction:
Ethanoyl chloride + alcohol
And what is this reaction called
- methyl ethanoate (Ester)
- HCl (white misty fumes)
CALLED: NUCLEOPHILIC ADDITION-ELIMINATION REACTION
What are the products of this reaction:
Ethanoyl chloride + primary amines
And what is this reaction called
- N-methyl ethanamide (N- substituted amides)
- HCl (white misty fumes)
CALLED: NUCLEOPHILIC ADDITION-ELIMINATION
What are acid anhydrides
- a molecule made from 2 carboxylic acids that are the same
How do you name acid anhydrides
- name the known carboxylic acid
- and removing -acid and adding -anhydride on the end
What is produced when acid anhydrides react with alcohols
- esters
- carboxylic acid
What is reacted with acyl chlorides to form esters and how is this better than the normal way of making esters
- phenols
- because it is faster at room temperature
How are esters normally made, what is the catalyst and why is this method not as good
- by reacting carboxylic acid and alcohols (phenols)
- H2SO4
- because it reacts slowly
What is esterification
- the formation of esters
What functional groups do esters have
-COO-
(Ester link)
Other than esters what does the reaction of carboxylic acids and alcohol produce and what type of reaction it is
- water
- reversible reaction
How are esters named
- the first bit is named from the alcohol ( take -oic acid off and put -yl)
- the second bit it named from the carboxylic acid ( remove the -oic acid and put -oate)
Name this ester:
Ethyl 2-methylpropanoate
What does hydrolysis of water involves
- removing water
How is 2 ways hydrolysis of esters can be sped up
- using and acid (acid hydrolysis)
- using a base (base hydrolysis)
Describe acid hydrolysis:
Products made?
Catalyst used?
Under what?
- use dilute acids to split an ester into CARBOXYLIC ACID and ALCOHOL
- use sulfuric hydrochloric acids
- under reflux
Where is the bond broken in acid hydrolysis
- Between the alcohol and the carboxylic acid (C-O bond)
What does an acid hydrolysis of esters look like
Describe base hydrolysis:
Products made?
Catalyst used?
Under what?
- carboxylate ion and alcohol
- sodium hydroxide
- reflux
Where is the bond broken in base hydrolysis
- between the alcohol and and the carboxylic acid (O-C bond)
What does a base hydrolysis of esters look like