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Chemistry U3/4 > U4 AOS1: Organic Compounds > Flashcards

U4 AOS1: Organic Compounds Flashcards

Structure, nomenclature and reactions

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1
Q

Organic molecules

A
  • Molecules of carbon compounds
  • C is almost always associated with H
  • C forms four strong covalent bonds
  • Can be naturally or synthetically produced
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2
Q

Polar vs non-polar

A
  • Polar – uneven electron distribution
  • Non-polar - even electron distribution
    • C–H bond is non-polar (low electronegative difference)

NOTE: The longer the hydrocarbon chain, the more non-polar it becomes (effect of functional group on the molecule lessens).

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3
Q

Saturated vs unsaturated molecules

A
  • Saturated – contains only single C–C bonds (alkanes)
  • Unsaturated – contains 1/more double or triple C–C bonds (alkenes or alkynes)
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4
Q

Bond energy and strength

A
  • Energy – quantity of energy required to break 1 mole of covalent bonds in the gaseous state
  • Strength – bond energy is a measure of bond strenth
    • The higher the bond energy, the stronger the bond
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5
Q

Degree of unsaturation

A
  • How many double bonds/ring structures a molecule has
  • Every time a molecule forms a double bond or a ring, there will be two fewer hydrogen atoms present
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6
Q

Isomers

A
  • Molecules with the same number and type of atoms (same molecular formula), arranged in different ways
  • Can have different physical and chemical properties
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7
Q

Alkanes

A
  • General formula: CnH2n+2 (n = no. carbons)
  • Have only single C–C bonds (saturated)
  • Can form isomers when they have 4/more carbons (can form branches)
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8
Q

Cyclohexane

A
  • General formula: CnH2n
  • Alkane arranged in a closed ring (no terminal carbon)
  • Saturated molecule

NOTE: A terminal carbon is the carbon at the end of the carbon parent chain.

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9
Q

Alkenes

A
  • General formula: CnH2n
  • Have at least one C–C double bond (unsaturated)
  • More reactive than alkanes
  • Double bond causes a ‘kink’ in the carbon chain, decreasing BP due to lower dispersion forces
  • Can form structural isomers when they have 4/more carbons atoms (location of C–C double bond changes)
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10
Q

Benzene

A
  • Molecular formula: C₆H₆
  • Unsaturated cyclic compound with 6 carbons
  • Each C is bonded to one H and two adjacent C
  • Very stable structure
  • Have a circle in the middle for skeletal formula
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11
Q

Haloalkanes

A
  • Alkane-based compounds whith 1/more halogen atoms bonded to the carbon chain
  • E.g. chlorine, bromine, fluorine, and iodine
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12
Q

Primary amines

A
  • Contain an amino (−NH₂) functional group
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13
Q

Primary amides

A
  • Amide (−CONH₂) functional group on a terminal carbon
    • Carbonyl group (C=O) bonded to a nitrogen atom (NH₂)
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14
Q

Alcohol

A
  • Contain a hydroxyl (–OH) functional group
  • Primary: C bonded to -OH is bonded to 1 alkyl group
  • Secondary: C bonded to -OH is bonded to 2 alkyl groups
  • Tertiary: C bonded to -OH is bonded to 3 alkyl groups (requires branching at the C attached to the –OH)
    • Very stable structure

NOTE: O−H bonds are highly polar (negative charge shifts towards O).

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15
Q

Aldehydes

A
  • Aldehyde (–CHO) functional group on a terminal carbon
  • C attached to the aldehyde group is always C number 1
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16
Q

Ketones

A
  • Carbonyl (C=O) group within the C chain (never at the end)
  • Number is added before the suffix (-one) to indicate which carbon the carbonyl group is attached to
17
Q

Carboxylic acids

A
  • Carboxyl (−COOH) functional group on a terminal carbon
    • Made up of a hydroxyl (−OH) and carbonyl (C=O) group
  • Able to donate H+ to a solution, so can act as a weak acid
18
Q

Non-branched esters

A
  • Ester (−COOC−) functional group within the carbon chain
  • Form when alcohols react with carboxylic acids
  • Naming: [alcohol part] –yl + [carboxylic acid part] –oate
19
Q

Naming organic compounds

A
  1. Name longest carbon chain
  2. Single/double bonds
  3. Name + locate functional groups
  • Only 1 suffix (group with the highest priority)
  • Prefixes alphabetical (lower priority groups)
  • Commas separate numbers
  • Hyphens separate numbers from words
  • No space between words
20
Q

Parent chain prefixes

A
  • 1 – Meth
  • 2 – Eth
  • 3 – Prop
  • 4 – But
  • 5 – Pent
  • 6 – Hex
  • 7 – Hept
  • 8 – Oct
21
Q

Prefixes when there are multiple of the same alkyl side chain

A
  • 2 – di
  • 3 – tri
  • 4 – tetra
22
Q

Intermolecular vs intramolecular forces

A
  • Intermolecular – bonds between molecules
    • Dispersion (NP)
    • Dipole-dipole (P)
    • Hydrogen bonding
  • Intramolecular – bonds within molecules
23
Q

Dispersion forces

A
  • Weakest type of intermolecular force
  • Non-polar
  • Present in all molecules
  • Stronger in molecules that are
    • Longer (more electrons and greater surface area)
    • Regularly shaped (less kinks)
    • Saturated (can pack together more tightly)

NOTE: Alkanes and alkenes only have dispersion forces.

24
Q

Dipole-dipole

A
  • Only occur in polar molecules
  • Increase boiling point, melting point and viscosity
25
Q

Hydrogen bonding

A
  • Type of permanent dipole-dipole attraction (very strong)
  • Occurs when H is bonded to nitrogen, oxygen or fluorine
  • Increase boiling point, melting point and viscosity

NOTE: Hydrogen bonds are not chemical bonds. They are forces of electrostatic attraction between adjacent molecules.

26
Q

Melting and boiling point of alkanes and alkenes

A
  • Low as they only have weak dispersion forces
  • The longer the carbon chain, the greater the strength of dispersion forces between molecules which ↑ MP & BP

NOTE: As melting and boiling points increase, so does viscosity.

27
Q

Viscosity

A
  • Resistance to flow
  • Increases as the forces of attraction between molecules increase (therefore, longer molecules have greater viscosity)
  • Decreases as temp increases as molecules move more quickly (higher kinetic energy available to overcome forces)
28
Q

Substitution reactions

A

Occurs when an atom or functional group in a molecule is replaced by another atom or group.

  • Between an alkane and halogen
    • E.g. bromine
    • UV light or heat is required to initiate the reaction
    • Produces a haloalkane
  • Between a haloalkane and an alkali
    • E.g. sodium hydroxide (NaOH)
    • Produces an alacohol
  • Between a haloalkane and ammonia (NH3)
    • No catalyst is required
    • Produces a primary amine
  • Between a primary alcohol and ammonia
    • Requires heat and alumina (Al₂O₃) as a catalyst
    • Produces a primary amine

NOTE: Ammonia only reacts with haloalkanes NOT alkanes.

29
Q

Addition reactions

A

Occurs when a small molecule is added to the double bond of an alkene. 2 reactants combine to form 1 product.

  • Hydrogenation: alkene + hydrogen
    • Requires a metal catalyst (e.g. nickel)
    • Hydrogen is oxidised and carbon is reduced (redox)
    • Produces an alkane
  • Halogenation: alkene + halogen
    • Can proceed at room temp w/o a catalyst
    • Produces a haloalkane
    • Can be used to test for double bonds
  • Hydration: alkene + water vapour
    • Requires heat, pressure and concentrated phosphoric acid (H₃PO₄) as a catalyst
    • Produces an alcohol
  • Polymerisation: alkene monomers
    • Produces a polymer (large molecule)
30
Q

Esterification reactions

A

Type of condensation reaction where a carboxylic acid and an alcohol react to produce a water molecule and an ester.

  • Carboxylic acid + primary alcohol
    • Reversible reaction
    • Requires heat and concentrated sulphuric acid (H₂SO₄(l)) as a catalyst to speed up the reaction
    • Produces an ester
31
Q

Hydrolysis reactions

A

Water is a reactant and is used to break the bonds in a molecule to produce new compounds. It is the reverse of an esterification (condensation) reaction.

  • Ester + water
    • Cannot occur at SLC
    • Requires heat and a dilute acid as a catalyst
    • Produces a carboxylic acid and an alcohol

TIP: Hydro means water and lysis is to break apart.

32
Q

Oxidation of primary alcohols

A

The primary alcohol is first oxidised to an aldehyde which is then further oxidised to a carboxylic acid.

  • Primary alcohol → aldehyde
    • Requires MnO₄⁻ (oxidant) and H+
    • Limit the heat of the reaction
    • Limit the oxidant available in the reaction
    • Remove the aldehyde as it’s being produced by distillation
  • Aldehyde → carboxylic acid
    • Requires MnO₄⁻ and H+
    • Higher temperatures
33
Q

Transesterification reactions

A

Process of exchanging an ester’s organic functional group with the organic group of an alcohol.

  • Triglycerides + alcohol (methanol)
    • Requires a catalyst (KOH)
    • Produces biodiesel and glycerol
34
Q

Condensation reactions (formation) of biomolecules

A
  • Proteins (polypeptides)
    • Peptide link joins amino acids
    • Water is released
  • Carbohydrates
    • Glycosydic link (−COC−) joins monosaccharides
    • Water is released
  • Lipids (fats and oils)
    • 3 long chain fatty acids react with glycerol
    • Water is released
35
Q

Hydrolytic reactions (break down) of biomolecules

A
  • Proteins
    • Requires water and enzymes
    • Peptide bond breaks, causing the protein to be broken down into individual amino acids
  • Carbohydrates
    • Requires water and enzymes
    • Carbs are broken down into monosaccharides
    • This produces glucose (main energy source)
  • Lipids (fats and oils)
    • Requires water and enzymes
    • Triglycerides broken down into fatty acids and glycerol

Chemistry U3/4 (17 decks)

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