alcohols Flashcards
what are alcohols
have the functional group of OH
what are the different types of alcohol
primary alcohols, secondary alcohols, tertiary alcohols (depending on number of alkyl groups)
alkenes can be made … from alcohols providing that …
sustainable
the alcohol has been made via fermentation of glucose from plants
what is dehydration
eliminating water
you can use it for eliminating water from alcohol to produce alkene
what is the non sustainable way of making alkenes
from crude oil
how to dehydrate alcohols
involves the use of an acid catalyst- sulfuric or phosphoric acid
ethanol => ethene and water
elimination mechanism- dehydration of alcohols
lone pair of oxygen will attach to H+ which comes from catalyst
the intermediate formed has a +1 charge on oxygen and the oxygen pulls electrons in C-O bond to break bond leaving unstable carbocation intermediate
carbocation loses a H+ and the electrons in C-H move to form C=C
ethene and water and hydrogen ion formed
dehydration of non primary alcohols
can lead to 2 different alkenes
dehydration of alcohols is conducted via … because dehydration leads to a ..
distillation
impure product
how do you purify the alcohol
distillation operate chemical by bpt
separation funnel and drying agent can remove any water
how to make cyclohexene
made from cyclohexanol by distillation, separation and purification
distillation-
add concentrate sulphuric and phosphoric acid and cyclohexanol into round bottomed flask and add anti-bumping granules to smooth boiling process
use heating mantle to warm reactants to 83 degrees not a bunsen burner as cyclohexanol is flammable
chemicals with bpt less than 83 degrees will evaporate and enter condenser to turn back to liquid as condenser has cold water running through wall
seperation-
add products into a separating funnel and add water to dissolve soluble impurities and create an aqueous solution
settling creates a 2 layer to form top layer- impure cyclohexene bottom layer-drain aqueous layer containing water soluble impurities- drain aqueous layer off
purification-
the impure cyclohexene and add to round bottom flash and add anhydrous calcium chloride and this will remove any substances remaining. invert flask and leave for 20-30 mins
hydration of alkenes
alcohols are produced
use steam and acid catalysts with a phosphoric acid catalyst
temp of 300 degrees and 60atm
fermentation
a sustainable alternative to ethene and steam when making ethanol
fermentation uses yeast in anaerobic conditions and the reaction is exothermic
glucose=>ethanol+carbon dioxide
what is yeast and what does it do
an enzyme and it converts glucose into CO2 and ethanol
optimum temperature- 30-40 degrees
what do you need to do to obtain pure ethanol after fermentation
fractional distillation
