alcohol's Flashcards
oxidation
-add acidified potassium dichromate
-primary alcohols get mildly oxidised to aldehydes so colour change form orange to green
-secondary alcohols get mildly oxidised to ketones so colour change from orange to green
-tertiary alcohols do not get oxidised so no colour change and remains orange
oxidation of primary alcohols
-add acidified potassium dichromate
-primary alcohols get mildly oxidised to aldehydes so colour change form orange to green
oxidation of secondary alcohols
-add acidified potassium dichromate
-secondary alcohols get mildly oxidised to ketones so colour change from orange to green
oxidation of tertiary alcohols
-add acidified potassium dichromate
-tertiary alcohols do not get oxidised so no colour change and remains orange
reaction to produce alcohols (electrophilic addition)
reaction type:
electrophilic addition
reagents:
alkene and steam
conditions:
heat and H3PO4 catalyst
products:
alcohol
reaction to produce Diol (oxidation)
reaction type:
oxidation
Reagents:
alkenes, cold dilute KMnO4
Conditions:
shaking of reagents
product:
diol
reaction to produce alcohol (nucleophilic substitution)
reaction type:
nucleophilic substitution
Reagents:
halogenoalkanes, aqueous NaOH
Conditions:
heat
product:
alcohol
reaction to produce primary/secondary alcohol (reduction)
reaction type:
reduction
Reagents:
aldehydes/ketones
Conditions:
NaBH4 or LiAlH4
product:
primary/ secondary alcohols
reaction to produce a primary alcohol (reduction)
reaction type:
reduction
Reagents:
carboxylic acid
Conditions:
NaBH4 or LiAlH4
or
H2, Ni catalyst and heat
product:
primary alcohol
reaction to produce alcohol (hydrolysis)
reaction type:
hydrolysis
Reagents:
esters
Conditions:
dilute acid or alkali heat
product:
alcohol
oxidation of primary alcohols
-oxidised to form aldehydes which can be oxidised to form carboxylic acids
oxidation of ketones
cannot be oxidised
oxidation of secondary alcohols
oxidised to form ketones only
oxidation of tertiary alcohols
cannot be oxidised
acidified potassium dichromate as an oxidising agent
-orange oxidising agent
-gets reduced in order for it it be an oxidising agent which requires H+ ions provided by the acidic medium
-when oxidised colour change from orange to green
Acidified potassium manganate as an oxidising agent
colour change from purple to colourless when oxidised
testing for oxidation products using Fehling’s solution
-Fehling’s solution is an alkaline solution contain copper(II) ions which act as the oxidising agent
-when warmed with an aldehyde it is oxidised to a carboxylic acid
-the clear blue solution turns opaque red due to the formation of a copper(1) oxide precipitate
-ketones cannot be oxidised so give a negative result
testing for oxidation products with tollens’ reagent
-Tollens’ reagent is an aqueous alkaline solution of silver nitrate in excess ammonia solution
-when warmed with an aldehyde, the aldehyde is oxidised to a carboxylic acid and a sliver mirror forms
-ketones cannot be oxidised and therefore give a negative result and no silver mirror forms
equation for combustion of alcohols
alcohol + oxygen → carbon dioxide + water
how can ethanol be produced
fermentation of sugars
problems with using ethanol as fuels
-ethanol has a lower density than gasoline so cars that run on ethanol must have a larger fuel tank or be filled up more often
how to overcome ethanol’s low energy density
-blending ethanol with gasoline or diesel increases the energy density and makes it safter in case of fires as fames are easier to see
conditions for dehydrating alcohols
-600 degrees c catalyst of aluminium oxide powder or porous pot
-excess hot, concentrated sulfuric acid or phosphoric acid can also be used as a catalyst (say this one as on ms it syas this as conditions for elimination reaction)
how do dehydration reactions work
-water molecule if formed form the -OH group of the alcholhol and the H+ from the acid catalyst
-the neighbouring hydrogen is then lost as a H+ ions, which regenerates the acid catalyst
oxidation of a primary alcohol to a aldehyde
-add to oxidising agent and warm
-distilled as aldehyde has a lower boiling point than alcohol
how do you oxidised a primary alcohol to a carboxylic acid
refluxing with excess oxidising agent
