Organics 6 Flashcards
Organics
The study of carbon compounds (except CO, CO2, CO3)
Carbon atoms have the unusual property of being able to …
… join with other carbon atoms to form chains
Homologous series of organic chemicals have
- compounds with the same general formula
- members with similar chemical properties
- members that show a trend in physical properties
- members which differ from each other by a CH2 unit
Function group
The part of the molecule that determines which homologous series it is a member of
• an atom or group of atoms which, when present in different molecules, causes them to have similar chemical properties
Highest precedent group…
- taxes suffixes
- all others take prefixes
RCOOH > aldehydes > ketones > alcohols > alkenes > halogenoalkanes
Alkanes
- hydrocarbons that contain only single bonds
- fully saturated
- CnH2n+2
Hydrocarbons
Compounds of hydrogen and carbon only
Cycloalkanes
- hydrocarbons joined in rings
- saturated
- two hydrogens less than the corresponding straight-chain alkane
Isomerism
When two molecules of the same molecular formula have a different arrangement of atoms
Structural isomerism
When atoms are arranged in a different order
Fuels
- released heat energy when burned
* one of the main uses of alkanes; readily, highly exothermic
Crude oil
- a mixture of a large number of hydrocarbon compounds
* undergoes fractional distillation to obtain fractions, then reformation to obtain fuels
Fractions
Consist of mixtures of hydrocarbons that boil within particular ranges
More useful fractions are those with
- lower boiling ranges
- generally occur in smaller proportions
- higher demand
- valuable
To solve the problem of supply and demand, we use
Catalytic cracking -> breaking C-C bonds
• 650°C (strong covalent bonds)
• Al2O3 catalyst
Cracking products
Alkanes break into smaller alkanes and alkanes, which can be used to make polymers
Engines
- straight chain alkanes do not burn very evenly, causing ‘knocking’ in a car engine
- cyclohydrocarbons burn more smoothly, giving fuel a higher octane number (more appropriate)
- solved by reforming
Reforming - description
- the process used to convert straight chained alkanes into ringed compounds (aromatic hydrocarbons)
- 500°C, platinum/rhodium catalyst
- e.g. benzene, methylbenzene
Reforming - definition
The processing of straight chain hydrocarbons into branched chain alkanes and cyclic hydrocarbons for efficient combustion
Aka. Isomérisation
Climate change
- hydrocarbon fuels produce CO2 when they burn
* CO2 is a greenhouse gas
Greenhouse gases
- when IR radiation from the sun hits the earth’s surface, it is absorbed and then re-radiated at a lower frequency
- a greenhouse gas absorbs this and concerts it to heat energy, warming the atmosphere
- burning fossil fuels increases the concentration of greenhouse gases in the atmosphere, causing climate change
Car engine pollutants
- in an engine, the fuel and air mix is passed into the combustion chamber and ignited
- powerful initial reaction is followed by less energetic processes
- to achieve maximum power, the gases are expelled from the chamber before combustion is complete
- results in CO and unburned hydrocarbons to be eject, causing pollution and smog
CO
- poisonous
* binds almost irreversibly to Hb, reducing O2 transport around the body
Photochemical smog
- unburned hydrocarbons tend to be react with the air, especially in the presence of sunlight
- can cause serious breathing problems o
Sulfuric acid rain
- fuels such as coal in power stations of contain sulfur
- converted to sulfur dioxide in combustion
- dilute sulfuric acid in atmosphere, dissolving
Nitric acid rain
- combustion in engines tjs replace at high temperatures and has sparks, allowing atmospheric oxygen and nitrogen to form nitrous oxides
- breaks the N2 triple bond
- forms dilute nitric acid
- forms NO-> toxic, smog
Pollutant carbon particulates
- produced by Diesel engines and unturned petrol engines
- caused global dimming (reflection of sun’s light)
- breathing problems
Catalytic converters
- rémove CO, NOx and unburned hydrocarbons form exhaust engines
- help to combat engine pollutants
- ceramic honeycomb coated w thin layer of catalyst metals (Pt, Pd, Rh) to give large SA
- catalyst provides th resurface to enable oxidisers (e.g. nitrous oxides) to react w reductants (e.g. unburnt hydrocarbons) to form less harmful CO2, N2 and H2O
- do not deal with CO2 effects
Reducing CO2
- no fossil fuels
* alternative fuels
Alternative fuels
- biofuels (biodiesel)
* alcohols formed from renewable resources
Biofuels
- formed by plants that absorb atmospheric CO2 to form the plant materials that are used; renewable
- carbon-neutral; no large-scale pollution
Bioethanol production
- requires fertilisers and pesticides that have taken energy (from oil) to make
- requires distillation
Biodiesel
- smaller carbon footprint, does not require distillation
* reacting vegetable oils w/ alkali + methanol
Combustion of alkanes
- react with oxygen to produce CO2 and H2O
* incomplète CO/C + H2O (less energy/mole)
Free radical substitution
- halogénation (Cl/Br) if alkanes (halogen substitués H atoms)
- because C-C and C-H relatively strong
- alkanes are v. Unreactive; photochemical réaction caused by UV light
- cyclical due to halogen regeneration at the termination stage
Free radical
- a reactive species which possesses an unpaired electron
- every time it finds another e-, it pings and creates another free radical
- so reactive that can cause cancer
Simplified equation of free radical substitution
- CH4 + X2 -> CH3X + HX
- the réaction does not necessarily stop at one substitution can produce dihalogeno-, trihalogeno- and tetrahalogeno- etc. with excess halogen
Production of free radicals
- homolytic fission
- a covalent bond breaks, and the atoms originally joined by the bonds each take one electron
- 2x unpaired electron shown as a dot ; no charge
- shows by a single headed curly arrow
Initiation
- only ever 1 stage
* halogen -uv-> 2x halogen free radicals
Why is it the halogen that undergoes homolytic fission?
- always the halogen, because diatomic halogen bind has lower bind energy than C-H bond, so the UV light breaks it first preferentially
- requires less energy to break
- not enough to break C-H
Propagation
- always two stages, with free radicals in reactants and products
- halogen free radical + alkane -> alkane free radical + hydrogen halide
- alkane free radical + halogen -> halogenoalkane + halogen free radical
- hydrogen halide bond forms because it has a higher bond energy
- chain reaction due to regeneration of halogen free radicals
Termination
- can be any number of steps
- reacts any free radicals to remove them
- causation if free radical does not generate firther free radicals; chain is terminated
- used structyral, not molecular formulae in equations
- 2x halogen free radicals -> halogen (regeneration)
- 2x alkane free radicals -> alkane (by-product)
- Halogen free radical + alkane free radical -> halogenoalkane (product)
If a question asks for the halogen to be substituted into w middle carbon in the chain
It is important to show the free radical on the correct carbon at the propagation stages
Alkenes
- hydrocarbons that contain one double bond
- unsaturated
- CnH2n
- functional: C=C (one σ and one π)
Cycloalkenes
- unsaturated
* CnH2n-2
Remember, when position isomers can occur…
… number need to be added to the name
σ bond
- normal bond
- electron cloud likes between the two atoms
- firmed by one sp2 orbital from each (overlapping)
- rotation can occur around the bond
- end-on overlap (forms a denser cloud)
- region of really high electron density (shared-pair)
π bond
- electron cloud lying above and below the planes two atoms
- side-on overlap of two p orbitals in each C atom
- rotation is restricted (stopped)
- weaker than the σ because it is not over the nuclei; doesn’t pull them together -> fast reaction
- overlap is less efficient because the highest e- density is not directly between nuclei
- resultant high e- density above and below the lines between the two nuclei
Nomenclature of alkenes
- multiple double bonds are indicated by ‘diene’ or ‘triene’, stem ends in a
- ‘en’ can go before other suffixes
Stereoisomerism
- e.g. E-Z isomerism, cis-trans isomerism (geometric isomerism)
- same structural formula, different spatial arrangement of atoms
E-Z isomerism
- due to restricted rotation around C=C that doesn’t exist around C-C
- needs two different groups/atoms attached to both end each of the double bonded Cs
Entgegen (E)
- higher priority groups on opposite sides of E
* looks like a Z
Zussamen
- higher priority groups on the same side of the C=C
* looks like an E
Naming E-Z isomers
- determined the priority groups on both sides of the double bond
- determined by atomic number
cis-trans isomerism
- a specific case of E-Z isomerism
* two of the substituent groups are the same
If asked to name an organic reaction…
… think REDOX
Alkene reactions
- more reactive than alkanes because of the double bond
* possible for the double bond to break, allowing each C to form a new bond (often energetically favourable)
Addition reactions in alkenes
- a reaction where 2 molecules react to produce 1
* double bond breaks, 1 species joins each side
Alkene addition with hydrogen
- hydrogenation
- reagent: hydrogen (bombard)
- conditions: nickel catalyst, heat
- functional group: alkene -> alkane
- réaction: addition/reduction (+H2)
Alkene addition with halogens
- halogénation
- reagent: Cl2/Br2 (dissolved in organic solvent)
- conditions: room temp and pressure, not UV light
- functional group: alkene -> dihalogenoalkane
- mechanism: electrophilic addition
- type of reagent: electrophile (Clδ+, Brδ-)
- type of bond fission: heterolytic
Alkene addition with hydrogen halides
- reagent: HCl/HBr
- conditions: room temperature
- functional group: alkene -> halogenoalkane
- mechanism: electrophilic addition
- type of reagent: electrophile (Hδ+)
- type of bond fission: heterolytic
- if the alkene is not symmetrical, the hydrogen adds to the carbon that’s already has the most hydrogen
Alkene addition with potassium managanate (VII)
- acidified KMnO4
- conditions: room temperature/cold -> not too vigorous
- type of reaction: oxidation
- observation: purple -> colourless
- used to test for the alkene functional group; would not change for alkanes
- functional group: alkene -> diol
KMnO4
- acidified solution
- oxidising agent
- provides oxygen in conjunction with a water molecule to produce two -OH groups which add across the double bond
Alkene addition with bromine water
- reagent BrOH (bromine dissolved in water)
- conditions: room temperature
- observation: orange -> colourless
- also used to test for the alkene functional group
- functional group: alkene -> halogenoalcohol
Alkene addition with steam
- reagent: steam
- conditions: 300-600°C, high pressure (70atm), conc. H3PO4 catalyst
- functional group: alkene -> alcohol
- reaction: hydration
- industrial: no waste products; high atom economy, easier and cheaper
Hydration
- water is added to a molecule
* H + OH add
Electrophilic addition premise
electron rich area in the double which allows the initial attack on the alkene by the electrophile
Electrophile
- a species attracted to an area of negative charge
* an electron pair acceptor
Formation of carbocation in electrophilic halogénation of alkenes
- alkenes pushes e-s in the π bond to bromine
- induces à dipole because the π electrons repel the e- pair
- Br2 becomes polar and electrophilic (Brδ+)
Electrophilic addition of hydrogen halide to alkenes
- Hδ+ is attracted to high e- density of double bind, drawing an e- pair out and forming a bond
- bond between bromine and hydrogen breaks; both e-s go to bromine (heterolytic fission)
- HBr is already polar due to electro negativities
- a carbon will only have 3 bonds, creating positive charge - carbocation
- bromide donates electron pair to carbocation, forming a bond
When addition reactions involve larger alkenes…
…. there can be multiple possible intermediates, depending on which carbon the hydrogen from the hydrogen halide joins
Markovnikov’s rule
During addition reactions, you predominantly form the most stable cation
Carbocations are stabilised by..
… induction; the positive charge on the C attracts e-s from connecting atoms, causing the charge to spread
Methyl groups have a
… higher inductive effect because they are higher in electron density (electron releasing, reduce charge on C)
Which carbocation will be the most stable?
- the more carbons attached to the positively charged carbon
* greater inductive effect
Heterolytic bond fission
- produces ions (which can be electrophiles or nucleophiles)
- nucleophile
- both electrons from the covalent bonding pair go to one atom
Addition polymers
Formed when monomers containing double bonds are polymerised
Polyalkenes
Are unreactive due to strong C-C and C-H bonds
Éthene uses and properties
- plastic bags
- bottles
- flexible
- easily moulded
- waterproof
- chemical proof
- low density
Propène uses and properties
- rope
- carpet
- stiffer
Disposal of polyalkenes
- no groups are susceptible to attack by water or natural organisms
- not décomposed by natural processes
- non-biodegradable, build your at landfills
Recycling of polyalkenes
- polymers sorted into type (automatically or with IR)
- melted and remoulded
- saves crude oil
- expensive in energy and manpower
Incinération of polyalkenes
- burnt at a high temperature
- used for energy generation
- high temperature prevents poisonous gases entering the air (e.g. HCl)
- emits greenhouse gases
- volume of rubbish is greatly reduced
Feedstock for cracking
- decomposition
- polymer is heated without oxygen
- decomposes into smaller molecules that can be used as fuel
Life cycle assessment
- materials and energy used to make them
- materials and energy used to maintain them
- materials, space and energy used to dispose of them
Improvements to disposal of polyalkenes
- rénove any waste gases produced during incineration
* make plastics which are biodegradable (e.g. polyethanol)
Halogenoalkanes
Functional group: halogen
Classification
Depends on the number of carbon groups attached to the carbon with the halogen (X) group
Preparation of halogenoalkanes
- react the appropriate alcohol with the halogenating
- chloro- : phosphorous pentachloride
- bromo- : potassium bromide, 50% H2SO4
- iodo- : red phosphorus w/ iodine
Test for OH
- phosphorus pentachloride (s) reacts with alcohols at room temperature
- used to prep chloroalkanes
C2H5OH + PCl5 -> C2H5Cl + HCl + POCl3
Preparation of bromoalkanes
- heat under reflux
- 50/50 mix
- H2SO4 + KBr -> HBr + KHSO4
- liberates hydrobromic acid
- HBr + C3H7OH -> C3H7Br + H2O
Preparation of iodoalkanes
- heat under reflux
- P + 3/2I2 -> PI3
- PI3 + 3ROH -> 3RI + H3PO3
PI3
- (phosphorus(III) iodide)
* has a lone pair - trigonal pyramidal
Conc. H2SO4 cannot be used …
… to make bromoalkanes or iodoalkanes as the halide ion is oxidised o the halogen
Heating under reflux
- stops solvent evaporating
* keeps réactions going
Halogenoalkane reactions
- v reactive!
- carbon-halogen bond is polar due to the electronegativity of H (draws e-s away from the carbon to which it is attached, leaving it δ+)
- δ+ attract negative ions, or molecules with negativity charged regions -> nucleophilic
Nucleophile
- a species attracted towards a region of positive
- an electron pair donor
- always have a lone pair
- e.g. OH-, H2O, CN-, NH3
Nucleophilic substitution
• swapping a halogen atom for another atom/ group of atoms
Aqueous potassium hydroxide nucleophilic substitution
- substitution with aqueous alkalis
- halogen is substituted by an OH group
- conditions: heat under reflux
- functional group: halogenoalkane -> alcohol
- role of reagent: nucleophile, OH-
- products: alcohols + halide ion
Why is OH- a stronger nucleophile than water?
It’s has a full negative charge leading to a stronger attraction to Cδ+
Silver nitrate solution nucleophilic substitution
- silver nitrate made by dissolving the solid in water
- halide ions react with silver ions, producing a silver halide precipitate
- precipitate only forms when the halide ion has left the halogenoalkane; rate of formation of precipitated used to compare halogenoalkane; rate of formation of precipitate used to compare halogenoalkane reactivity
Ethanol as a cosolvent
in the presence of water, halogenoalkanes hydrolyse (poor nucleophile)
• much slower because water and halogenoalkanes are immiscible; low collision rate
• ethanol can interact both water (hydrogen bonding) and halogenoalkanes (polar and non-polar regions) acting as an emulsifier
• allows water and halogenoalkanes to mix, increasing reaction rate
Hydrolysis
The splitting of a molecule by a reaction with water
Comparing halogenoalkane
- the quicker the precipitate is formed, the faster the substitution reaction, the more reactive the halogenoalkane
- reaction rate depends on the C-X bond energy; the lower the energy the reaction
Results of silver nitrate solution rate comparisons
- chloroalkane: no precipitate forms
- bromoalkane: precipitate forms after 15mins
- iodoalkane: precipitate forms after 5 mins
Iodoalkanes > bromoalkanes > chloroalkanes
C-I is the weakest of the three; most easily broken
Ammonia solution nucleophilic substitution
- reagent: NH3 dissolved in ethanol
- conditions: heating under pressure in a sealed tube
- type of reagent: nucleophile NH3
- products: amine + hydrogen halide
- hydrogen halide then reacts with remaining ammonia to produce ammonia halide
- further reaction can occur, leading to a lower yield of smoke; using excess ammonia prevents
Why is ammonia a strong nucleophile
The nitrogen is highly electronegative
Potassium cyanide nucleophile
- reagent: KCN
- conditions: ethanolic, heated under reflux
- type of reagent: nucleophile (CN-)
- products: nitrile
- extends the carbon chain
Nitrile
R-C=_ N
Nucleophilic substitution 1 - mechanism
- halogenoalkanes are susceptible to attack by nucleophiles
- the halogen is electronegative draws bonding electron pair towards itself creating Cδ+
- Cδ+ invites nucleophilic attack
- 1st step is the slow step
- carbocation is planar; nucleophilic attack from either side
Nucleophilic substitution 2 - mechanism
- transition state - not an actual substance, just a representation of the middle of the reaction
- attaching a catalytic antibody attaching to TS to lower Ea
How to tell which nucleophilic substitution mechanism will occur
- consider carbocation states; 3° is the most stable and therefore best for Sn1
- consider steric hindrance
- 1°: Nu- lone pair not hindered
- 3°: Nu- lone pair is sterically hindered by bulky methyl groups
- 2° could be either
- 1° does not do Sn1 because it would form an unstable primary carbocation
Halogenoalkane élimination
- reagent: KOH/NaOH in ethanol
- role of reagent: base, OH-
- condition: heat (boiling)
- functional group: halogenoalkane -> alkene
- products: alkene + hydrogen halide + water
- structurally, the halogen and the H of the adjacent C are eliminated (unsymmetrical 2° and 3° can have structural isomers)
How do halogenoalkane structure affect reaction?
- 1° halogenoalkane tend towards substitution
* 3° halogenoalkane tend towards elimination
Uses of halogenoalkanes
- refrigerants, fire retardants, pesticides, aerosol propellants
- chloro- , chlorofluoro- used as solvents
- CH3CCl3 -> solvent used in dry cleaning
- low flammability
- many uses have been stopped due to toxicity and effect detrimental effect on ozone layer
Test for halogenoalkanes
- heated with aqueous NaOH (release halide ions)
- RX + OH- -> ROH + X-
- excess dilute nitric acid (removes remaining OH- ions)
- AgNO3
- Ag+ (aq) + X- (aq) -> AgX (s)
Reactivity of halogenoalkanes
- 3° halogenoalkanes react fastest because although there is no wait time for collision during Sn1
- in Sn2 nucleophile must be correctly oriented and collide by coming from opposite
Alcohols
- functional group: OH
- CnH2n+1OH
- suffix: -ol
- hydroxy- (used in RCOOH, remember to show number!)
Carbonyl groups
- involves in alcohol oxidation
* C=O
Ketone
- simplest: propanone
- 5 or more means it’s necessary to add the number
- -one
Aldehyde
- C=O is at the end of the carbon chain
- no number needed
- -al
Properties of carbonyls
- very flammable (like all other organic compounds); illustrated by whoosh bottle
- used as fuels because they burn v. quickly
- used as solvents because they evaporate v. quickly
- liquid at room temperature because of the hydrogen bonding between molecules (higher BP to corresponding alkanes)
- as chain length increases, dipole-dipole and H bonding loses relevance compound to London forces
Small alcohols intermolecular forces
- dipole-dipole
- hydrogen
- London
Soluble
Large alcohols
- dipole-dipole
- hydrogen
- much more London
Less soluble
Combustion of alcohols
- conditions: clean flame
* products: CO2 + H2O
Alcohol reactions with sodium
- observations: effervescence (H2), mixture gets hot, sodium dissolves, white solid produced
- white solid = sodium alkoxide
- uses: test for alcohols
Sodium alkoxide
Ethoxide -> pale yellow solid, ionic properties, soluble
Oxidation of alcohols - basics
- loss of hydrogen
- hydrogens attached to the C adjacent to the OH group must be lost
- reagents: 0.3mol H2SO4 and K2Cr2O7 (aq)
0.3mol H2SO4 + K2Cr2O7
[O] -> oxidising agent, is reduced
H2SO4 -> provides H+ ions, reduced to H2O
K2Cr2O7 -> easily controllable
(Cr2O7)2- + 14H+ + 6e- -> 2Cr3+ + 7H2O
Partial oxidation of alcohols - primary
- alcohol -> aldehyde
- conditions: limited amount of dichromate (excess), warm gently
- method: add one reagent dropwise to the other, distill off the aldehyde as it forms
- orange solution -> green solution
- Cr2O7)2- -> 2Cr3+
- products: aldehyde + water
Why must the aldehyde be distilled off?
To prevent further oxidation into a carboxylic acid
Full oxidation of primary alcohols
- doesn’t always happen, need other right conditions
- excess dichromate, heat under reflux
- products: RCOOH + water
- orange solution -> green solution
- Cr2O7)2- -> 2Cr3+
Full oxidation of secondary alcohols
- only H attached to the adjacent C, produces ketone, cannot oxidise further
- excess dichromate, heat under reflux
- products: ketone + water
- orange solution -> green solution
- Cr2O7)2- -> 2Cr3+
- ketone can be distilled off because it is a volatile product in a involatile mixture (BPs of 50°C)
Heating under reflux - diagram labels
- open top to prevent pressure build up and explosion
- Liebig condenser
- cold water in at bottom and out at the top
- pear-shaped flask
- solvent, reactants and anti-bumping granules
- heat (Bunsen/heating mantle)
Anti-bumping granules
- provide a large SA for bubbles to form on
- prevents vigorous boiling and splashes caused by bumping by allowing smaller bubbles
- smooth boiling
Why use a heating mantle?
Flammable substances
How does heating under reflux work?
- as the reactants are heated, the volatile liquids boil off
- converted back into liquid in the condenser and return to the flask
- allows heating for longer, increasing reaction time
Why can’t tertiary alcohols be oxidised with acidified dichromate?
There are no hydrogens attached to the carbon adjacent to the OH group
Fehling’s (Benedict’s)
- used to distinguish between carbonyls
- reagent: contains Cu2+ ions (blue) + 2,3-dihydroxybutanedioic acid
- conditions: heat gently
- only aldehydes oxidise, reducing Cu2+ to copper(I) oxide (Cu2O)
- observations -> blue solution -> red ppt
- ketones do not react
Tollens’
- used to distinguish between carbonyls
- ammoniacal silver nitrate
- observations: aldehyde produces silver mirror through reduction of Ag+
ammoniacal silver nitrate
Solution of silver nitrate, sodium hydroxide and ammonia solution
General indicator of carbonyls
- 2,4-DNPH
* produces a yellow-orange precipitate
Alcohol elimination
- reagent: conc. H3PO4 (acid-catalysed, dehydrating agent)
- conditions: heat under reflux
- functional group: alcohol -> alkene
- some 2° and 3° alcohols can give more than one product, when the double bond forms between different carbon atoms (E-Z isomerism)
- provides a possible route to polymers without using monomers derived from oil
Dehydrating agents
Do what you think.. remove water molecules from larger molecules
Na2SO4 anhydrous
- insoluble in organic liquid
- not react w/ organic liquid
- drying agent
Distillation
• used to separate an organic product from it’s reacting mixture
Purification
- solvent extraction
- put the distillate of impure product into separating funnel
- wash product with NaHCO3, inverting and releasing pressure from CO2 produced
- wash product NaCl (aq)
- allows layers to separate through inversion in the funnel, holding the stopper
- run and discard aqueous layer
- run organic layer into clean, dry conical flask; add 3 spatulas of anhydrous Na2SO4
- devant liquid into distillation flask
- distill for pure product
NaHCO3
Neutralises any remaining reactant acid/acid catalyst
NaCl (aq)
Helps separate organic layer from aqueous layer
Solvent extraction
1) mix organic solvent and oil-water mixture in a separating funnel; separate oil layer
2) distil to separate oil from organic solvent
3) add anhydrous CaCl2
4) decent to remove
Prior to purification
1) materials and reagents are mixed and heated under reflux
2) crudely distilled (w/out thermometer)
After drying
1) filter liquid through small tuft of mineral wool into a pear-shaped flask
2) distill w/thermometer - bulb adjacent to still-head side-arm
3) collect product over particular temperature range
Measuring BP
- determines liquid purity and identifies product
- distill/boil in a heating oil bath
- constant and standard pressure
- thermometer above the level of the surface of the boiling liquid; measuring the temperature of the saturated vapour
- not very accurate -> several substances have the same BP
General nomenclature
- if the suffix starts with a vowel, remove e from stem
- if it is a consonant, or multiple groups, do not remove e
- functional groups take precedence over branched chains in giving lowest number
- multiple functional groups or side are given in alphabetical order
Chain isomers
Same molecular formula, different carbon skeleton structure
Position isomers
Same molecular formula, different structures due to different positions of the same functional groups on the same carbon skeleton
Functional group isomers
- same molecular formula
* atoms arranged to give different functional groups
Carboxylic acids
- RCOOH
- -oic acid
- no number necessary because acid group is always at the end of the chain
- can have -dioic acid
Test for RCOOH
- Na2CO3
* effervescence (CO2)
Disadvantages of biofuels
- less food crops may be grown
- rain forests cut down to provide land
- shortage of fertile soils
