Organic Chemistry 1 - Homologous Series and Reactions Flashcards
Substitution Reaction
One functional group is substituted for another (eg -Cl for -OH, or -H for -Br). Two reactants and two products.
Conditions for substitution reaction between an alkane and a hydrogen halide
UV light
Substitution Reaction - Synthesis of Alcohols
Haloalkane passed through sodium hydroxide (NaOH) or potassium hydroxide (KOH) to produce an alcohol.
Why can alkenes undergo addition reactions?
Presence of a double bond
Reactants for the hydrogenation of alkenes (Addition)
alkene + hydrogen gas
Conditions for the hydrogenation of alkenes (Addition)
Ni catalyst and 150 degrees C temperature
What is produced when an alkene reacts with a hydrogen halide?
A haloalkane (eg a chloroalkane when an alkene reacts with HCl)
Conditions for reaction between an alkene and a hydrogen halide
room temperature (standard lab conditions)
Describe what happens when an alkene is bubbled through bromine water.
The alkene reacts with bromine to produce a dibromoalkane (bromine atom added to either side of the double bond)
Conditions for the Halogenation of Alkenes (Addition)
room temperature (standard lab conditions)
Conditions for the hydration of alkenes to form an alcohol
Phosphoric acid catalyst, 300 degrees C and 60-70 atm pressure
Describe the hydration of ethene (reactants and products)
Ethene reacts with steam to produce ethanol
What happens when an ester is hydrolysed in acidic conditions?
Ester link is broken and water is added, producing a carboxylic acid and an alcohol
Conditions required for hydrolysis of an ester
Aqueous acid (H+) or strong alkali (OH-)
Green Chemistry Principles
The Green Chemistry approach strives to achieve sustainability at the molecular level.
Homologous series
A series of organic compounds that have a similar chemical structure and chemical properties
Organic compounds
Compounds consisting of carbon atoms most commonly covalently bonded to hydrogen, nitrogen, phosphorus or oxygen atoms
Functional group
Specific groups of atoms within a compound that affect the properties of the compound.
Alkane General Formula
CnH2n+2
Alkene General Formula
CnH2n
Haloalkane General Formula
CnH2n+1 X
Isomers
Are organic molecules having the same molecular formula but a different structural formula.
Why do the longer hydrocarbon chains take more heat energy to change state from solid to liquid or liquid to gas?
The longer the chain, the more intermolecular forces there are between the molecules, and require more energy to break.
When the hydrocarbon goes through a state change of liquid to gas, which bonds are broke?
Weak intermolecular forces are broken when the hydrocarbon reaches its boiling point and transitions from liquid to a gas. The covalent bonds between the atoms do not beak. This would required a higher amount of energy.
What is cracking
Cracking is an example of a thermal decomposition reaction, where large organic molecules (usually alkanes) are broken down into smaller molecules (usually a smaller alkane and an alkene) using heat and a catalyst.
Compare complete and incomplete combustion (of hydrocarbons, alcohols or esters)
In complete combustion a fuel is burned in excess oxygen:
fuel + oxygen → carbon dioxide + water
In incomplete combustion the fuel is burned in limited oxygen
fuel + oxygen → carbon monoxide + water or
fuel + oxygen → carbon + water
Substitution reaction
Oneatom(or functional group) is swapped with another atom (or functional group).
Alkanesundergo asubstitution reactionwithhalogensin the presence of light.
Addition reaction
Double bond breaks and atoms are added to either side
Bromine water test (including equation, including conditions)
A test to determine whether a solution or gas contains alkenes. Performed at room temperature with bromine water (Br2(aq))
Bromine water goes from orange or brown to colourless (decolourises) when it is mixed with an alkene. There is no change upon mixing with alkanes.
Br2 + CH2CH2 → CH2BrCH2Br
Hydrogenation (addition reaction with H2) equation and conditions
Alkene + hydrogen (150degreesC and Ni catalyst)→ alkane
Hydration (addition reaction with H2O) equation and conditions
Alkene + water (steam) (phosphoric acid catalyst, 60-70 atm + 300degrees C) → alcohol
Ethanol production (including advantages and disadvantages) Fermentation of glucose
Fermentation of glucose:
C6H12O6 (yeast catalyst) → C2H5OH + CO2
Advantages: Simple method and uses renewable resources (glucose from sugar cane or sugar beet)
Disadvantages: Not a continuous process, slow reaction and produces low purity ethanol that requires purification
Ethanol production (including advantages and disadvantages) Hydration
Ethene + steam
C2H4 + H2O (g) → C2H5OH
Advantages: Continuous process, reaction is fast and produces high purity ethanol
Disadvantages: Uses non-renewable resources, equipment is expensive
Alcohol Homologous Series
Organic compounds containing a hydroxyl (R-OH) group are called alcohols
Carboxylic acid functional group and naming conventions
Functional group is R-COOH, name ends in -oic acid. Carbon in functional group is designated carbon number 1 in all cases
Alkyl Halides
Organic compounds containing halogens are called alkyl halides. The halo group is added as a prefix to the name.
Ester functional group and naming conventions
Functional group is R1-COO-R2. The carbon double bonded to oxygen is designated carbon number 1 in the main chain (the -oate, eg methanoate). The other carbon chain is designated as an alkyl group (eg methyl) and named as a prefix.
Can methyl methanal exist?
No - the methyl group would be an extension to the main chain so this would be ethanal
Can 2-ethylbutane exist?
No - the ethyl group would be classed as an extension of the main chain. This would be 3-methylpentane (draw it out!).
Differences between ketones and aldehydes
Ketones have the C=O group in the middle of the carbon chain, whereas aldehydes have the C=O group at either end. Aldehydes can be oxidised to form carboxylic acids, whereas ketones cannot be oxidised.
Designation of alcohols as primary, secondary or tertiary
Primary alcohols have zero or one carbon bonded to the carbon containing the functional group. Secondary alcohols have two carbons bonded to the carbon containing the functional group. Tertiary alcohols have three carbons bonded to the carbon containing the functional group.
Differences in oxidation of primary, secondary or tertiary alcohols
Primary alcohols can be oxidised partially to form aldehydes, or completely to form carboxylic acids. Secondary alcohols can be oxidised to form ketones but no further. Tertiary alcohols cannot be oxidised.
