6: Organics I Flashcards
Hydrocarbons definition
Molecules consisting of only hydrogen and carbon atoms
Empirical formulae definition
The lowest whole number ratio of atoms
Molecular formulae definition
The actual number of each type of atom
General formulae definition
The algebraic formula for a homologous series
Structural formulae definition
A minimal detail layout that shows the arrangement of atoms
Displayed formulae definition
A drawing showing all covalent bonds
Skeletal formulae definition
Simplified organic formulae without hydrogen atoms on alkyl chains
Addition reaction definition
Two molecules react together to produce one
Elimination reaction definition
The removal of a small molecule (often water) from the organic molecule
Substitution reaction definition
Swapping a halogen atom for another atom/group of atoms
Hydrolysis reaction definition
Adding water to an organic molecule
Polymerisation reaction definition
Two molecules added together to form 1 longer chain
Structural isomers definition
Same molecular formula but different spatial arrangement of atoms
Homologous series definition
Families of organic compounds with the same functional group and general formula
Functional group definition
An atom or group of atoms which cause molecules to have similar chemical properties
Shape of a Z-isomer
C
Shape of an E-isomer
Z
General formula for alkanes
C(n)H(2n+2)
How are alkane fuels obtained?
The fractional distillation of crude oil
Reforming definition
Turning straight chain hydrocarbons into branched chain alkanes and cyclic hydrocarbons
Benefits of reforming
Allow for more efficient combustion
Harmful chemicals produced during combustion of alkane fuels and associated danger
CO toxic, NO toxic and can form smog, NO2 toxic and forms acid rain, SO2 forms acid rain, C global dimming and respiratory problems, unburnt hydrocarbon form smog
Benefits of catalytic converters for waste gases
Cause CO2 and NO; hydrocarbons and NO; to react together, forming N2 and other products which are less harmful
Advantages of biofuels
Renewable, Allows fossil fuels to be used for other purposes, no risk of large scale pollution
Disadvantages of biofuels
Less space for food crop, shortage of fertile soil
Free radicals definition
Species with an unpaired electron
Formation of free radicals
Formed from homolytic fission of a covalent bond
Combustion of ethane
2(C2H6) + 7(O2) → 4(CO2) + 6(H2O)
(T) Free radical substitution of alkanes equations
Use ethane: 1 initialisation, 2 propagation, 3 termination
Reason for low yield of free radical substitutions
Further substitutions can occur
General formula for alkenes
C(n)H(2n)
Bonding in a C=C bond
1 σ and 1 π bond
Electrophile definition
An electron pair acceptor
Conditions and type of reaction for: alkene + hydrogen → alkane
- Addition/reduction
- Nickel catalyst
Use of hydrogenation
Hydrogenating C=C bond in vegetable fats and oils to produce margarine
Conditions and type of reaction for: Alkene + halogen → dihalogenoalkane
-Electrophilic addition
(T) Alkene + halogen → dihalogenoalkane
-π bond induces dipole in X(2)
(T) Alkene + hydrogen halide → dihalogenoalkane
-Major product formed via more stable carbocation
Conditions, reaction, use and type of reaction for: Formation of alcohol from alkene
-Alkene + steam + [O] → alcohol
-KMnO4 in acidified solution
-Purple MnO4(-) ions turn colourless
Test for alkenes
Reaction and use of reaction for: Alkene + bromine water
- C2H4 + BrOH → CH2BrCH2OH
- Bromine water turns colourless
- Can be used to test for alkenes
Reaction, type of reaction and conditions for: hydration of alkene
- Alkene + H2O → alcohol
- Hydration, electrophilic addition
- 70atm, 300-600°C, Conc H3PO4 catalyst
Methods for disposing of waste polymers
- Incineration
- Recycling
- Feedstock for cracking
Benefits and negatives of incinerating waste polymers
+Releases energy for electricity production
+Greatly reduces volume of rubbish
-Some toxins released
Benefits and negatives of recylcing
+Saves raw materials
-Expensive to sort polymers
Benefits and negatives of feedstock for cracking
+Polymers broken down into small, more useful molecules
+Saves raw materials
Examples for what are biodegradable polymers made from
Maize and starch
Nucleophile definition
An electron pair donor
Reaction, type of reaction and conditions for: Formation of alcohol from halogenoalkane
- Halogenoalkane + KOH(aq) → alcohol
- HUR
- In aqueous solution
- Nucleophilic substitution
(T) Halogenoalkane + KOH(aq) → alcohol for primary and tertiary halogenoalkane
Primary → SN1, Secondary → SN2
Reason for for different paths for Halogenoalkane + KOH(aq) → alcohol
The methyl groups prevent the OH(-) from attacking the halogenoalkane, Primary don’t do SN1 as they would form and unstable carbocation - tertiary is stabilised by surrounding methyl groups
Reaction for: halogenoalkanes(haloethane) + silver nitrate(ethanol)
CH3Ch2X + H20 → CH3CH2OH + H(+) + X(-); X(-) + Ag(+) → AgX
Colours for AgI, AgBr, AgCl
AgI - yellow precipitate, AgBr - cream precipitate, AgCl - white precipitate
Reaction, type of reaction and conditions for: formation of a nitrile from halogenoalkane
- halogenoalkane + KCN → nitrile
- Nucleophilic substitution
- HUR
- Same as halogenoalkane + KOH(aq)
Reaction, type of reaction and conditions for: formation of amine from halogenoalkane
- halogenoalkane + NH3 → nitrile
- Nucleophilic substitution
- Heat under pressure in sealed tube (Not HUR)
(T) Halogenoalkane + NH3 → nitrile
-Further substitutions
Reaction, type of reaction and conditions for: formation of alkene from halogenoalkane
- halogenoalkane + KOH(ethanol) → alkene
- In ethanol
- Heat
- Elimination
- CH3CH2CH2X +KOH(ethanol) → CH3CH=CH2 + KX + H20
How to determine rates of hydrolysis in halogenoalkanes
Time taken for precipitate to form when silver nitrate is added
Halogenoalkane reactivity trends
iodo>bromo>chloro>fluoro
Reaction, type of reaction and conditions for: formation of chloroalkane from alcohol
- Ch3Ch2OH + PCl5 → CH3CH2Cl + POCL3 + HCl
- HCl given off → test for alcohol
Reaction, type of reaction and conditions for: formation of bromoalkane from alcohol
- CH3CH2OH + HBr → CH3CH2Br + H20
- HBr formed by 50% conc H2SO4 + KBr
Reaction, type of reaction and conditions for: formation of iodoalkane from alcohol
- 3(CH3CH2OH) + PI3 → 3(CH3CH2I) + H3PO3
- PI3 produced in situ by red phosphorus and iodine
Reaction, type of reaction and conditions for: oxidation of primary alcohols
- Primary alcohol → aldehyde → ketone
- CH3CH2CH2OH + 2[O] → CH3CH2COOH + H20
- HUR
- Reagent: K2Cr2O7 + dilute H2SO4
- Orange Cr2O7(2-) → green Cr3+
Reaction, type of reaction and conditions for: oxidation of secondary alcohols
- Secondary alcohol → aldehyde
- CH3CH(OH)CH3 + [O] → CH3C(O)CH3 + H2O
- Reagent: K2Cr2O7 + dilute H2SO4
- Orange Cr2O7(2-) → green Cr3+
Reaction, type of reaction and conditions for: oxidation of tertiary alcohols
No reaction
