Organic Chemistry I Flashcards
Which alcohols make carboxylic acids when oxidised?
Primary Alcohols
Which alcohols make ketones when oxidised?
Secondary Alcohols
What 4 reactions can alcohols do?
Combustion
Halogenation
Oxidation
Elimination
Describe the solubility of alcohols.
- alcohols are miscible in water because of the O-H group
- this depends on the length of the non-polar part of the hydrocarbon
- however longer hydrocarbon chains decrease solubility as they cannot hydrogen bond with water
What is a primary, secondary, and tertiary alcohol?
- primary alcohols are bonded to a carbon that is bonded to 1 other carbon
- secondary alcohols are bonded to a carbon that is bonded to 2 other carbons
- tertiary alcohols are bonded to a carbon that is bonded to 3 other carbons
What happens in the combustion of alcohols?
Alcohols burn to produce CO2 and H2O (if its complete)
What happens in chlorination of alcohols?
PCl5 is added to the alcohol, where any OH’s will be replaced by Cl.
e.g. PCl5 + C2H5OH -> C2H5Cl + POCl3 + HCl
- the POCl3 must be separated from the product using fractional distillation and the HCl will produce misty fumes
What conditions must chlorination take place under?
- with dry ether (anhydrous conditions)
- because PCl5 will react with water
Are primary or tertiary alcohols easier to chlorinate and why? (visualise)
- tertiary are easier
- because tertiary are more reactive
- the CH3 groups push e- towards the central carbon and there fore weaken the C-O bond
- so the O will fall off more easily
What happens in bromination of alcohols?
This is a TWO STEP reaction.
- add a mixture of KBr and concentrated H2SO4 to the alcohol
1. KBr + H2SO4 -> KHSO4 + HBr
2. HBr + C2H5OH -> C2H5Br + H2O
This is a nucleophilic substitution reaction.
What happens in iodination? This is a TWO STEP reaction.
- add a mixture of red phosphorus and iodine
- then heat under reflux
1. 2P + 3I2 -> 2PI3
2. 3C2H5OH + PI3 -> 3C2H5I + H3PO3
What conditions are needed for the elimination of alcohol? (aka dehydration)
- heat with concentrated phosphoric (V) acid
- OR heat with NaOH/KOH in ethanolic solution
- this makes alkenes
What is a Z isomer
when both groups with the higher priority lie on the same side (top or bottom) of the C=C double bond
What is an E isomer
When both groups with the higher priority lie on opposite sides (top and bottom) of the C=C double bond
Whats a hydrocarbon
a compound made of hydrogen and carbon only
What is a skeletal formula
shows how the atoms are arranged, but without showing carbons
whats a homologous series
compounds with the same functional group that differ in formula only
what is a functional group
a group of atoms within a molecule that has specific chemical properties
whats an isomer
molecules with the same molecular formula but whose atoms are arranged differently
whats a structural isomer
molecules with the same molecular formulae but different structural formula
what are the three kinds of structural isomerism
positional
functional
chain
what is stereoisomerism
molecules with the same structural formula but with different arrangements in space
What kinds of stereoisomerism are there
E-Z
Optical
whats catalytic cracking
using a zeolite catalyst and heat to break long hydrocarbons into shorter hydrocarbon chains and small alkenes such as ethene
whats a biofuel
fuels made form plant components
what is a free radical
a species with an unpaired electron
whats homolytic fission
where a bond breaks and one electron goes to each atom that was participating in the bond, forming free radicals
whats heterolytic fission
where a bond breaks and both electrons in the bond go to one atom that was participating in the bond, forming ions
free radical substitution steps
initiation - formation of free radicals using UV light
propagation - free radical reacts a non-free-radical species, forming more free radicals as well as new molecules
termination - two free radicals meeting and forming a bond
whats a carbocation
species with positively charged carbon
whats a primary, secondary and tertiary carbocation
one,two and three alkyl group/s directly bonded to positively charged carbon
what is the trend in carbocation stability and explain jjt
it increases as the alkyl group number increases
because of the positive inductive effect from the alkyl groups, as they push their electrons towards other things, in this case the positive carbocation
therefore, the positive charge is reduced and the carbocation becomes more neutral, more stable
