3. Organic AS Flashcards
define homologous series
a group of organic compounds that have the same functional group, but each successive member differs by CH2
define structural formula
shows how the atoms are bonded to each carbon atom in a molecule
define displayed formula
2D representation of an organic molecule showing all its atoms and their bonds
define skeletal formula
simplified display formula with all the carbon and hydrogen bonds removed
what is the general formula of alcohols?
C(n)H(2n+1)OH
what is the general formula of aldehydes?
C(n)H(2n+1)CHO
what is the general formula of ketones?
C(n)H(2n)O
what is the general formula of carboxylic acids?
C(n)H(2n+1)COOH
what is the general formula of esters?
C(n)H(2n)O2
what is the general formula of amines?
C(n)H(2n+1)NH2
what is the general formula of nitriles?
C(n)H(2n+1)CN
define molecular formula
shows the number and type of each atom in a molecule
define empirical formula
shows the simplest whole number ratio of the elements present in one molecule of the compound
define aliphatic compound
straight or branched chain and also includes cyclic organic compounds that do not contain a benzene ring
what are structural isomers?
compounds that have the same molecular formula but different structural formula
what is chain isomerism?
when compounds have the same molecular formula, but their longest hydrocarbon chain is not the same e.g. pentane and 2,2-dimethy propane
what is positional isomerism?
arise from differences in the position of a functional group in each isomer. the functional group can be located on different carbons. e.g butanol and 2-butanol
what is functional group isomerism?
same molecular formula but different functional group e.g. butanol and ethoxyethane
how does cracking work?
large hydrocarbon molecules are fed into a steel chamber and heated to a high temp and passed over aluminium oxide catalyst
what are the products of complete combustion?
co2 and h2O
what are the products of incomplete combustion?
CO/C and H2O
what is the initiation step of free radical substitution?
what is homolytic fission?
when each atom takes one electron from the covalent bond
what is the propagation step?
what is the termination step?
what are the products from nucleophilic substitution?
a halogen is substituted for another atom or group of atoms. products formed are alcohols, amines, and nitriles
what are the products from elimination?
a hydrogen halide is eliminated and an alkene is formed
what are the reagents and conditions for the formation of alcohols undergoing nucleophilic substitution?
reagents: aqueous NaOH or KOH with ethanol
conditions: warm
what are the reagents and conditions for the formation of nitriles undergoing nucleophilic substitution?
reagents: ethanolic solution of KCN
conditions: heated under reflux
what are the reagents and conditions for the formation of amines (primary) undergoing nucleophilic substitution?
reagents: ethanolic solution of excess ammonia
conditions: heated under pressure
what are the reagents and conditions for elimination?
reagents: ethanolic NaOH
conditions: heated
give the free radical substitution for when CFCs react with the ozone
describe the sigma and pie bonds in ethene and how they arise
1)Each carbon atom uses three of its four electrons to form σ bonds
2)Two σ bonds are formed with the hydrogen atoms
One σ bond is formed with the other carbon atom
3)The fourth electron from each carbon atom occupies a p orbital which overlaps
sideways with another p orbital on the other carbon atom to form a π bond
4)This means that the C-C is a double bond: one σ and one π bond
how are sigma bonds formed?
from the end to end overlap of atomic orbitals
how are pie bonds formed?
sideways overlap of adjacent p orbitals
what is the positive inductive effect?
Alkyl groups push electron density towards the carbocation making it energetically more
stable; the more alkyl groups the carbocation is bonded to, the more stabilised it is (tertiary>secondary>primary)
what are the reagents, conditions and products of hydrogenation (electrophilic addition)?
what are the reagents, conditions and products of electrophilic addition with steam?
what are the reagents, conditions and products of electrophilic addition with hydrogen halides?
what are the reagents, conditions and products of electrophilic addition with halogens?
how do you test whether a compound is unsaturated?
mix with bromine water which should decolorise
why are the disposal of polymers a challenge?
due to their unreactivity, non-biodegradability and formation of harmful combustion when burnt
what are some of the solutions of plastic pollution?
feedstock recycling, mechanical recycling,
what are primary alcohols oxidised to and how?
aldehydes and using acidified K2Cr2O7
what is the colour change when primary and secondary alcohols are oxidised using K2Cr2O7?
orange to green
what are secondary alcohols oxidised to and how?
ketones and using acidified K2Cr2O7
how can you form an alcohol using electrophilic addition?
reagents: alkene and steam conditions: heat Phosphoric acid catalyst
how can you form an alcohol using oxidation?
reagents: alkenes and cold dilute KMnO4
conditions: shaking of reagents
how can you form an alcohol using nucleophilic substitution?
reagents: halogenoalkanes and aqueous NaOH
conditions: heat
how can you form an alcohol using reduction?
reagents: aldehydes and ketones
conditions: NaBH4 or LiAlH4
how can you form an alcohol using hydrolysis?
reagents: esters
conditions: dilute acid or alkali and heat
what can primary alcohols be oxidised to?
aldehydes and then further oxidation to carboxylic acids
what is the oxidising agent for alcohols?
acidified K2Cr2O7 or acidified KMnO4
how can you test for an aldehyde?
Fehling’s (blue to brick red) or Tollen’s reagent (silver nitrate in excess ammonia, form a silver mirror)
what happens if you test ketones using Fehling’s or Tollen’s reagent?
no change as they cannot be oxidised further
what are the reagents and conditions of elimination reaction of alcohols?
reagents: hot catalyst Al2O3 powder/excess hot conc H2O4/H3PO4
how do you test for carboxylic acids?
add NaHCO3 and CO2 gas is formed
