Chapter 22 - Families of Organic Compounds Flashcards
What is a tetrahedral carbon?
Carbon that has four single bonds
Chloroalkane
Compound in which one or more of the hydrogen atoms in an alkane molecule have been replaced by chlorine atoms
How do you name a chloroalkane?
- Select longest carbon chain
- Name after parent alkane
- Indicate number of chlorine atoms by prefixes
- Use numbers to indicate position
Uses of chloroalkanes
- Chloroform was one of the earliest anaesthetics (trichloromethane)
- Solvents: tipex, removes oil stains
- CFCs
- Paint stripper
Solubility of chloroalkanes
- Non-polar molecule
- Not soluble in polar water
- Soluble in non-polar solutions
Intermolecular bonding of chloroalkanes
- Rarely found in nature
- Mostly liquid at room temperature
- Low boiling point due to Van der Waals forces between molecules
What is the general formula for alcohols?
CₙH₂ₙ₊₁OH
What is the functional group of alcohols?
hydroxyl (hydroxide) group
-OH
Functional group
Atom or group of atoms which is responsible for the characteristic properties of an organic compound or series of organic compounds
How do you name an alcohol?
- Select longest chain of carbon atoms to which the -OH group is attached
- Name after parent alkane, but change -e to -ol
- Number from end that gives lowest value to the carbon attached to the -OH
- Indicate the position of -OH with a number e.g butan-2-ol
Primary alcohol
Carbon atom joined to the -OH group is attached to only one other carbon atom e.g ethanol
Secondary alcohol
Carbon atom joined to the -OH group is attached to two other carbon atoms e.g propan-2-ol
Tertiary alcohol
Carbon atom attached to the -OH group is attached to three other carbon atoms e.g 2-methylpropan-2-ol
What do industrial alcohols have in them to prevent consumption?
Have methanol as an additive (denaturing) plus a purple dye. e.g methylated spirits
Uses of ethanol
- Only alcohol you can drink
- Large quantities can cause coma, vomitting and death
- Relaxes muscles and slows reactions
- Is addictive and can lead to liver disease and brain damage
- Perfumes, aftershaves, deoderant
- Polishes, varnishes, dyes
- Solvents
- Fuel
What is the legal blood/alcohol limit for driving?
20mg per 100cm³ blood
Intermolecular bonding of alcohols
- Higher boiling point than corresponding alkanes
- Liquid at room temperature
- Higher boiling point due to presence of polar -OH group which forms hydrogen bonds between alcohol molecules and requires more energy to break
Solubility of alcohols
- Miscible with water due to both being polar → hydrogen bonds
- Mix so well that distillation cannot separate effectively → have to use calcium oxide to dry out fully
- Solubility decreases as chain gets longer as the man chain is non-polar even though the -OH is polar
What is a planar carbon?
When a carbon has less than four single bonds, and a double or triple bond
What is the functional group of aldehydes?
-CHO
O=C-H
How do you name aldehydes?
Named from alkanes
Name ends in -a
Functional group must be at the end of the carbon chain
What is the general formula for aldehydes?
CₙH₂ₙ₊₁CHO
Aldehyde uses
• Methanal (formaldehyde) dissolved in water is called formalin and is used in embalming
What is the only aldehyde that’s gas at room temperature?
methanal
What is the name of the aldehyde that smells like almonds?
benzaldehyde
Intermolecular bonding of aldehydes
- Carbonyl group (C=O) is very strongly polar due to difference in electronegativity values
- No hydrogen bonding exists as H is not bonded to an electronegative element
- Permanent dipole-dipole exists between the O of one molecule and the C of another
Boiling points of aldehydes
- Due to d-d bonds, boiling points are much higher than alkanes
- Lower than corresponding alcohols as there is no hydrogen bonding
What are ketones?
Similar to aldehydes except the functional group is joined to two carbons, and is not at the end of the chain like aldehydes
How do you name ketones?
Names end in -one
Uses of ketones
- Butanone is a strong plastic liquid glue, designed for ABS plastics especially
- Solvents
- Nail polish remover
Intermolecular bonding of ketones
- C=O is polar, rest is non-polar
* dipole-dipole
Solubility of aldehydes
- Lower members soluble in both polar and non-polar
- Soluble in water due to polar C=0 forming hydrogen bond with the H⁺ in water molecule
- Solubility decreases as chain length increases
- All aldehydes are soluble in non-polar solvents
Boiling points of ketones
- Higher boiling points than alkanes
- Lower than alcohol
- Due to d-d
Solubility of ketones
- Soluble in polar and non-polar for same reasons as aldehydes
- As chain length increases solubility decreases
- Longer chains only soluble in non-polar
What is the functional group of carboxylic acids?
carboxyl functional group -RCOOH
How do you name carboxylic acids?
ending in -oic acid
What are carboxylic acids made up of?
A C-OH from an alcohol and C=O from an aldehyde or ketone
Uses of carboxylic acids
- Methanoic acid (formic acid) found in stings of nettles and ants
- Ethanoic acid (acetic acid) in vinegar
- Propanoic acid and benzoic acid are food preservatives
What causes the smell of rancid butter?
butanoic acid
What causes the smell of human sweat?
Mix of carboxylic acids
What causes the smell of smelly socks?
butanoic acid
Intermolecular bonding in carboxylic acids
- Two hydrogen bonds are very strong (at room temperature)
* Form clusters called dimers
Boiling point of carboxylic acids
High boiling point due to two hydrogen bonds
Solubility of carboxylic acids
- Short chains soluble in water (due to hydrogen bonding with the water molecules) and non-polar
- Solubility decreases as the non-polar chain length increases
What is the functional group of esters?
Just like carboxylic acids except the H on the -OH is replaced by R’ to give -OR’ (but there is still a C=O bond)
How do you name an ester?
The original acid group changes from -oic to -anoate and the -R group that replaced the -H on the acid is listed as an alkyl substitute,
The carboxylic acid gives the main chain of the esters name and the alcohol gives the side chain
Esterification
The formation of an ester. Made by reacting an alcohol with a carboxylic acid in the presence of a catalyst (usually concentrated sulfuric acid). It is an example of a condensation reaction
Condensation reaction
Chemical reaction in which two molecules combine to form a larger molecule with the loss of a smaller molecule such as water
Where does the single oxygen in the ester come from?
The alcohol, not the carboxylic acid
Uses of esters
- Smells in nature
- Perfumes
- Fats and oils
- Used to make soap
- Polyesters
Bonding in esters
- Permanent dipoles between O and C
- O bonds with the C of another molecule
- Van der Waals between the Hs of molecules
Boiling point of esters
- Medium boiling points
* Lower members are volatile
Solubility of esters
- Short chains are soluble in both
* Long chains not soluble in polar water but are soluble in non-polar
Describe the arrangement of electrons in a benzene ring
- Each carbon has four electrons in their outside shell - three in sigma bonds and one in pi
- P orbitals all overlap with the orbitals next to them to form electron clouds above and below the plane
- The six electrons are delocalised
- This gives extra stability and the benzene doesn’t react like other alkenes do
Delocalised electrons
Free to move around the full cloud; not restricted to any atom
Is benzene a polar or non-polar molecule?
All the C-C bonds are the same length, hence benzene is non-polar planar molecule
Uses of benzene
- Organic solvent (but is carcinogenic so methylbenzene is used)
- Aromatic compounds used in making dyes, detergents, insecticides, chemical indicators
- Cocaine, heroin, aspirin, morphine, paracetamol
What is the organic natural aromatic product in almonds?
Benzaldehyde
What is the organic natural aromatic product in tea?
Caffeine
What is the organic natural aromatic product in cigarettes?
Nicotine
What is the organic natural aromatic product in poppies?
Opium
What is the organic natural aromatic product in orange peel?
Limonene
What is the organic natural aromatic product in cinchona trees?
Quinine
What is the organic natural aromatic product in mould?
Penicillin
Steam distillation
Separation process used to isolate compounds at temperatures below their decomposition temperatures. It is carried out by bubbling steam through the material and distilling off the immiscible liquids
What is the main constituent of clove oil?
eugenol
Emulsion
Dispersion of small droplets of one liquid in another liquid in which it is not soluble
Principal of Steam Distillation
A mixture of two immiscible liquids boils at a temperature that is below the boiling point of each of the individual liquids. The hot mixture of water vapour (from the steam) and oil (from the plant) is passes through a condenser and the distillate collected contains a mixture of water and oil
What colour is the emulsion that collects in the graduated cylinder at the end of the distillation in the clove oil experiment?
milky
Liquid-liquid extraction
A technique in which two immiscble liquids (eg oil of cloves and water) are separated using a solvent (eg cyclohexane) in which one of the components of the mixture (in this case the clove oil) has slightly higher solubility than the other (in this case the water), i.e the organic component is removed from the emulsion by dissolving this organic component in an organic solvent
Why is a white powder added into the conical flask containing the organic layer in the liquid-liquid extraction part of the clove oil experiment? What was this white powder
The magnesium sulfate forms clumps that stick to the sides and bottom of the conical. It is a drying agent and absorbs water
