Unit 4.3 Alcohols and Phenol Flashcards
Tips wise, how do i even go abouts efficiently learning mechanisms n stuff
Don’t make the same mistake for physics
(totally unrelated to the question)
The whiteboard merchant.
What’s the difference between primary alcohols and secondary alcohols?
(2 thingies)
- Primary alcohol = OH technically on either side
- Secondary alcohol = OH on the “second” carbon
How do u convert halogenoalkanes into alcohols?
(2 similars + 1 thing)
- Nucleophilic substitution
- Hydrolysis
- Forms a primary alcohol
What are the conditions required to convert halogenoalkanes into alcohols?
(2-way)
- Heat to reflux
- with aq sodium hydroxide
Class of mechanism of converting halogenoalkanes into alcohols?
Nucleophilic substitution
Show me the equation and mechanism using potassium hydroxide and 2-bromobutane
(Halogenoalkanes into alcohols)
(Hm.)
The whiteboard buddy
C4H9Br + KOH -> C4H9OH + KBr
Show nucleophilic substitution for:
1. CN- and 1-chloropropane
2. NH3 and 1-bromobutane
(Heavily whiteboard based)
- No eqn :(
- But u could at least try form the equation right?:
H3CCH2CH2Cl + CN- -> H3CCH2CH2CN + Cl-
Couldn’t tell u for 2.
What’s the purpose of the reduction of aldehydes and ketones?
Form primary and secondary alcohols
What do u need to reduce ketones and aldehydes?
(2 compounds)
- Sodium borohydride (NaBH4)
- Lithium aluminium hydride (LiAlH4)
What’s the jig with Lithium aluminium hydride?
(2-way)
- LiAlH4 must be dissolved
- in ethoxyethane (dry)
How to tell if it’s oxidation or reduction within a chemical equation?
(2 features)
- [O] = oxidation
- [H] = reduction
What are ketones reduced to?
Secondary alcohols
Show chemical equation of the reduction of propan-2-one indicating conditions required.
(You should use a whiteboard)
CH3(C=O)CH3 + 2[H] -> CH3CH(OH)CH3
Show the mechanism of the reduction of propan-2-one
(Whiteboard?)
Where’s your whiteboard
What’s the mechanism used for the reduction of ketones?
Nucleophilic addition
What are aldehydes reduced to?
Primary alcohols
Show chemical equation of the reduction of ethanal indicating conditions required.
(You should use a whiteboard)
CH3C(=O)H + 2[H] -> CH3CH(OH)H
Show the mechanism of the reduction of ethanal
(Whiteboard?)
Where’s your whiteboard
What’s the mechanism used for the reduction of aldehydes?
Nucleophilic addition
What other compound can be reduced to primary alcohols?
Carboxylic acids
What must u use (and its conditions) to reduce carboxylic acid to primary alcohols?
(3 things)
- Lithium aluminium hydride (LiAlH4) which…
- Must be used under anhydrous conditions
- Dissolved in ethoxyethane (diethyl ether)
Show chemical equation of the reduction of propanoic acid indicating conditions required.
(You should use a whiteboard)
H3CCH2C(=O)OH + 4[H] -> H3CCH2CH2(OH) + H2O
(LiAlH4)
What is the “Lucas Test”?
(2-way)
- Test to distinguish between
- the different classes of alcohols
How is the Lucas Test performed?
(2 steps each w/ halves)
1) Small amount of zinc chloride added as catalyst
1.5) & concentrated hydrochloric acid
2) Observe cloudiness
2.5) … the formation of insoluble chloro-compound
What do u observe for primary alcohols with Lucas Test?
(2 things)
- Stays colourless
- No indication of a reaction
What do u observe for secondary alcohols with Lucas Test?
(2 things)
- Cloudiness
- Slowly appears
What do u observe for tertiary alcohols with Lucas Test?
(2 words)
- Cloudiness
- Instantaneous
Show the chemical equation for:
1. Primary alcohol reacting with HCl
(Lucas Test)
(You should use a whiteboard)
1° = H3CH2OH + HCl -> H3CCH2Cl + H2O
Show chemical equation for:
2. Secondary alcohol reacting with HCl
(Lucas Test)
(You should use a whiteboard)
2° = H3CCH(OH)CH3 + HCl -> H3CCHBrCH3 + H2O
What would u need to prepare bromoalkanes?
(3 things)
- Mixture of potassium bromide,
- and concentrated sulfuric acid
- A primary alcohol (it seems)
What is “in situ” for the preparation of bromoalkane?
(2-way)
- Produces hydrogen bromide (HBr) within reaction
- that can attack the alcohol
Chemical equation of the preparation of bromoalkanes?
(You should use a whiteboard)
H3CCH2OH +HBr -> H3CCH2Br + H2O
Chemical equation of the preparation of bromoalkanes “in situ”?
(You should use a whiteboard)
2KBr + H2SO4 -> 2HBr + K2SO4
What does the reaction of Alcohols with Ethanoyl chloride form?
(2-way)
- Allows formation of sweet smelling compounds:
- Esters
Purpose of esters?
(2 features)
- Used as solvents
- Flavourings and perfumes
Chemical equation of the reaction between propan-1-ol and ethanoyl chloride?
(You should use a whiteboard)
H3CCH2CH2OH + H3CC(=O)Cl -> H3C(=O)OCH2CH2CH3 + HCl
What does the reaction of Alcohols with Carboxylic acid form?
… Esters…
What must be needed for the reaction of Alcohols with Carboxylic acid?
(1 thing + 2-way)
- Heat
- Small quantity of concentrated sulfuric acid
- … that acts as a catalyst
How does the carboxylic acid undergo nucleophilic attack during the reaction with alcohols?
(2-thing-ies)
- Conc. sulfuric acid protonates the carboxylic acid
- Nucleophilic attack by an alcohol
How is the ester gained after the reaction of alcohols with ethanoyl chloride & carboxylic acids?
(3 things)
- Distilled off soon as they formed
- To draw equilibrium to the right hand side
- Only if they have low molecular masses
How do esters have lower boiling points than the alcohols and carboxylic acids, from which they are formed…
They don’t form hydrogen bonds
Describe phenol
(2 things + 2-way)
- Simplest aromatic alcohol
- Toxic white solid (no contact with skin)
- Forms slightly acidic solution
- …. in water
Show me a diagram explaining why phenol forms slightly acidic solution in water
Where’s your whiteboard.
“Phenol” ⇌ Phenoxide ion + H+ or H3O+
How can the phenoxide ion charge be stabilised?
(2-way)
- Via delocalisation through
- the ring system
What’s the pH of aq of phenol?
5 - 6 pH
What does the acidity of phenol allow the creation of?
Show me.
Salt:
acid + alkali = salt + water
Show the equation of phenol w/ sodium hydroxide to form sodium phenoxide
(You should use a whiteboard)
Where’s your whiteboard?
“Phenol” + NaOH -> “Sodium phenoxide” + H2O
What are 2 tests to “test” for phenol?
- Reaction with Br/Bromine water
- Reaction with iron(III) chloride solution
What’s the observation with phenol reacting with Br/Bromine water?
(2 things)
- White ppt forms
- Br solution/water decolourises
Equation of phenol reacting with Br/bromine water?
(You should use a whiteboard)
Where’s your whiteboard?
Phenol + 3Br2 -> “What.” + 3HBr
What’s the colour of FeCl3 solution (Iron (III) chloride solution)
(2-way…?)
- Red/brown
- (yellow 0.1M)
What colour complex is gained from phenol reacting with FeCl3?
Violet
Which test for phenol doesn’t do colouration to an alkyl alcohol?
Reaction with iron(III) chloride solution
(FeCl3)
Why do we need to use an acid chloride to esterify a phenol?
Doesn’t react with carboxylic acids
Show the equation of phenol with ethanoyl chloride
(You should use a whiteboard)
H3C(=O)Cl + phenol -> “Phenol ethanol” + HCl
MUST USE ur book for most equations + mechanisms.
And, always spam ppq