3.5 alcohols Flashcards
State name of H2C(OH)CN
2-hydroxyethanenitrile
State name of H2C(OH)CH2NH2
2-hydroxyethylamine
State name of H3CCH2CHO
propanal
*it is a aldehyde as the carbonyl is bonded to another hydrogen atom
State name of CH3COCH2CH2CH3
2-pentanone
*It is a ketone as carbonyl compound is bonded to two other carbon atoms
State name of H3CCH2COOH
Propanoic acid
*it is a carboxylic acid as carbonyl is bonded to an OH group
State the reaction equation of Direct hydration and state the reagents and conditions
CH2=CH2(g) +H2O (g) -> CH3CH2OH
Reagent : H2O
Conditions : concentrated phosphoric acid / SiO2 coated in H3PO4 catalyst
& High temperature & High pressure
Two main method for ethanol production
Direct hydration of ethene
Fermentation of glucose
State the reaction equation for fermentation
Also state the conditions needed
C6H12O6 -> 2CH3CH2OH + 2CO2
Conditions : enzymes from yeast
No air / no oxygen
Temperature of 30 - 40 degrees
Explain why neither a low temperature nor a high temperature is suitable for fermentation
Temperature too low: reaction too slow
* Temperature too high: destroys or denatures yeast enzyme
Give name of type of reaction involved in formation of the two alkenes
Elimination or dehydration
Butan-2-ol reacts with concentrated sulfuric acid to prodcue three isomeric alkenes
State mechanism
Explain how this reaction can lead to the formation of each of the three alkenes
Elimination
H+ ion is lost from the C, the carbocation that is adjacent to +C to which the -OH was attached to
Loss of H+ ion from the 1st carbon in the chain leads to but-1-ene
Loss of H+ ion from the 3rd carbon leads to but - 2 -ene
But-2-ene is formed as a mixture of E/Z isomers
Alcohol A is (CH3)2CHCH(OH)CH3. Name IUPAC name of structure of isomer A that cannot be dehydrated to form an alkene by reaction with concentrated sulfuric acid
H3CC(CH3)2CH2OH
A compound has the structural formula CH3CH2CH=CHCH2CH2OH
Give structural formula of organic product formed when this compound is dehydrated using concentrated sulfuric acid
CH3CH2CH=CHCH=CH2
Use equations to show that ethanol produced by fermentation is carbon neutral meaning no CO2 emissions are released into the atmosphere when using bio-ethanol as a fuel
- Photosynthesis:
6CO2 + 6H2O → C6H12O6 + 6O2 - Fermentation:
C6H12O6 → 2CH3CH2OH + 2CO2 - Combustion:
2CH3CH2OH + 6O2 → 4CO2 + 6H2O
* 6CO2 are taken in during photosynthesis
* A total of 6CO2 are released during fermentation and combustion of ethanol
(use ethanol)
Write reaction equation for oxidation of a primary alcohol into into an aldehyde and an aldehyde turning into a carboxylic acid
State reagents and conditions for each reaction
Primary alcohol → Aldehyde
CH3CH2OH + [O] → CH3CHO + H2O
Reagent : acidified potassium dichromate (K2Cr2O7) - is represented by capital [O]
Conditions : Heat under distillation
Aldehyde → Carboxylic Acid
CH3CHO + [O] → CH3COOH
Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux
(Use ethanol)
The oxidation of a primary alcohol to a carboxylic acid is a two-step process, but both steps can be done in one go. Show reaction equation, state reagents and conditions of a primary alcohol turning into a carboxylic acid
Reaction equation : CH3CH2OH + 2[O] → CH3COOH + H2O
Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux, excess oxidising agent
Secondary alcohols can only be oxidised to ketones.
Show reaction equation, state reagents and conditions of oxidation of secondary alcohols (use propan-2-ol)
Reaction equation : CH3CH(OH)CH3 + [O] → CH3COCH3 + H2O
Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux or distillation
Which alcohols cant be oxidised
Tertiary alcohols
State formula for when CH3CH2CH(OH)COOH reacts with acidified potassium dichromate (VI)
CH3CH2COCOOH
Butan-1-ol reacts with acidified potassium dichromate (VI). State the type of reaction that occurs and the change in colour of the
potassium dichromate(VI) solution.
Type of reaction is oxidation
Colour change : orange to green
State formula for butanedioic acid
HOOCCH2CH2COOH
Write an equation for this oxidation reaction of butane-1,4-diol into butanedionic acid (HOOCCH2CH2COOH)
HOCH2CH2CH2CH2OH + 4[O] -> HOOCCH2CH2COOH + 2H2O
*Hydrogens and oxygens must both be balanced
Explain why a water bath is used to heat a mixture of ethanol and acidified potassium dichromate and why it is preferred over a bunsen burner
Eliminate / reduce fire risk
as the alcohol is flammable
State purpose of glass beads in a flask
to prevent bumping