Mod 7: Organic Chemistry Flashcards
What is a hydrocarbon?
Hydrocarbons are the simplest organic compounds, made up of only carbon and hydrogen.
How do alkanes, alkenes and alkynes differ?
Alkanes are saturated molecules, alkenes and alkynes are not. This is because all carbon-carbon bonds in alkanes are single, while alkenes have at least on double bond, and alkynes have a triple.
General formula for an alkene?
What type of organic compound representation is this?
Structural - shows the bonds between all the atoms
General formula for an alkane?
General formula for an alkyne?
What is an alkyl?
Alkyl groups are substituents or branches on organic molecules
What type of organic compound representation is this?
Empirical - the simplest ratio of atoms
What type of organic compound representation is this?
Condensed structural formula - arrangement of atoms without bonds
What type of organic compound representation is this?
Molecular - Number of atoms in a molecule
What is an isomer?
An isomer is a different structural configuration of the same chemical formula.
What is the molecular formula?
Molecular formula outlines all of the atoms in a molecule, without showing its structure
What is the empirical formula?
Empirical formula gives the simplest ratio of atoms in the molecular formula.
What is the structural formula?
The structural formula shows all of the bonds and atoms in a molecule.
What is the condensed structural formula?
The condensed structural formula shows the structure and atoms of a molecule, without showing the bonds.
What is skeletal formula?
Skeletal formula shows the carbon skeleton of a molecule, with as well as functional group bonds.
What is a functional group?
Chemical term used to describe a specific atom or group of atoms attached to an organic compound, that determines its chemical properties.
Are hydrocarbons polar or non-polar molecules? Explain with reference to the bonds present in a hydrocarbon.
Hydrocarbons are non-polar. This is because:
- Generally symmetrical
- Dipoles cannot be formed as the electronegativity difference is too low.
What’s carbonyl group?
A carbon double bonded to an oxygen.
What’s carboxyl group and its important property?
A carbonyl attached to a hydroxyl group. It is always attached to the end of a molecule.
What’s ester group?
Carboxyl group, but it cannot be at the end of a carbon chain.
What are the two types of isomers? Then what are the types of types of isomers and what they are.
Two types of isomers are structural and stereo.
There are three types of structural:
- Chain, a rearrangement of the carbon skeleton
- Position, a rearrangement of functional groups
- Functional group, a different type of functional group is present
How do you determine the boiling point of organic compounds?
Look at the intermolecular forces present - stronger is higher
Look at the shape of the molecules - straighter is higher
Look at size - bigger is higher
List the IUPAC priority list for functional groups. (10)
From strongest to weakest:
Carboxyl, amide, aldehyde, ketone, hydroxyl (alcohol), amino, alkene, alkyne, halogen and alkyl.
What is a haloalkane?
An alkane, but with one or more hydrogens replaced with a halogen.
What is an alcohol?
When the hydroxyl function group (OH) is attached to a saturated carbon atom.
How does classification of alcohols work?
Primary, Secondary and Tertiary: Number of alkyl groups bonded to the ASSOCIATED carbon atom.
What is a primary amine?
When amino functional group (NH2) is attached.
How does the classification of primary amines work?
Primary, secondary and tertiary based on the number of alkyl groups attached to the nitrogen atom.
What is the difference between an aldehyde and a ketone?
Aldehydes always have carbonyl groups at the end of a molecule.
Ketones always have the carbonyl group within the molecule.
What is a carboxylic acid and its special property?
It has a carboxyl group at the end of the molecule.
What is a primary amide?
A molecule containing a carbonyl attached to an amino group.
How do you name esters?
The first word is based on the carbon atoms attached to the oxygen atom, with suffix (-yl)
The second is based on the carbon atoms containing the carbonyl, with suffix (-anoate)
Suffixes of every functional group
Carboxyl: -oic acid
Amide: -amide
Aldehyde: -al
Ketone: -one
Hydroxyl: -ol
Amino: -amine
Alkene: -ene
Alkyne: -yne
Haloalkane: None
Prefixes/alternative names of every functional group
Carboxyl: None
Amide: carbamoyl-
Aldehyde: formyl-
Ketone: oxo-
Hydroxyl: hydroxy-
Amino: amino-
Alkene: -an- becomes -en-
Alkyne: -an- becomes -yn-
Haloalkane: halo-
Compare a soap and a detergent.
Both are surfactants, materials that decrease the surface tension of liquids. Soaps are a type of detergent, called anionic detergents, derived from non-petrochemically derived sources. The polar head of a soap will always be negatively charged and a carboxyl group.
Structure of detergents?
All detergents have a non-polar hydrocarbon chain and a polar head. The charge of the polar head determines the type of detergent we’re dealing with: anionic, cationic or non-ionic.
How do you test for a saturated compound?
Mix in Bromine water with the compound. The Br2 will react with the unsaturated compound, decolourising the Br2. If the Br2 does not decolourise, no reaction has occured, and the compoundis saturated.
What is Halogenation?
Addition reaction of halogens to unsaturated compounds. No conditions required as halogens are highly reactive.
What does it mean when a compound is volatile?
Weak intermolecular forces, evaporates easily at room temp
Types of combustion of alkanes
Complete: Occurs in excess of oxygen, produces carbon dioxide and water.
Incomplete: Occurs in lack of oxygen, produces carbon monoxide or carbon (soot) and water.
Incomplete combustion is more likely with long-chain alkanes, as stronger intermolecular forces make it harder to vaporise.
Explain the like dissolve like rule.
Polar solvents dissolve polar solutes as the polar ends of the molecules become attracted to each other through strong intermolecule bonds.
Non-polar solvents dissolve non-polar solutes due to their similar intermolecular forces, which allows the solute to evenly disperse throughout the solvent and create a solution.
They do not dissolve with each other as they are non electrostatically attracted to each other, so rather than dissolving or dispersing, they stay separate, forming layers or droplets in solution.
What is an addition reaction?
When a compound is unsaturated, it has available electrons to form new bonds.
Why can’t ketones and tertiary alcohols be oxidised?
An oxidation reaction is where there is a transfer of electrons, and the species being oxidised loses electron density, while another gains. Alcohols are oxidised when a carbon atom loses electron density by breaking a bond to hydrogen and form a bond with a more electronegative element like oxygen. Ketones and tertiary alcohols have no hydrogens to break bonds with.
What is hydrogenation?
Addition reaction of hydrogen atoms to unsaturated compounds. Requires the presence of a metal catalyst like platinum, palladium or nickel. A Lindlar catalyst is required to prevent an alkyne reacting to an alkane.
What is Hydrohalogenation?
Addition reaction of HX, where Markovnikov rule will determine where the H and X go across a double bond.
What is hydration?
Addition reaction of water to alkenes to form alcohols, or ketones/aldehydes to alkynes. Based on Markovnikov. Requires dilute sulfuric acid catalyst, alkynes require mercury (II) compounds.
What is a substitution reaction?
Occurs in saturated molecules, as they cannot undergo addition reactions.
Halogen substitution in Alkanes?
Usually only with Br or Cl. Requires the presence of UV light.
Halogen substitution in Alcohols?
The halogen replaces the hydroxyl group, breaking off to form water. Tertiary alcohols are the most reactive.
Dehydration of Alcohols?
Requires concentrated sulfuric acid catalyst. Produces an alkene and water.
Oxidation of alcohols?
Primary alcohol –> aldehyde –> Carboxylic acid
Secondary alcohol –> ketone
Requires acidified permanganate (MnO4-) or dichromate (Cr2O7-2) ions.
What is a condensation reaction?
Combining two molecules to form a larger molecule and a small molecule (normally water.)
What is esterification?
Carboxylic acid + Alcohol in the presence of concentrated sulfuric acid will produce an ester + water. Esterification is reversible, so you must distill off the ester as it is made.
What does the charge of a detergent’s polar head do?
Detergents, if charged, form salt with an oppositely charged ion to form a salt, which will split when added to water.
How do detergents clean?
The structure of detergents, have a non-polar tail and a polar head allows them to form bonds with both polar and non-polar solvents.
What is a micelle?
As the non-polar tails form bonds with non-polar stuff like oil, and the polar-head form bonds with water, they form a micelle, which forms a sphere around the grease.
How do you test for hydroxyl groups?
React a non-aqeuous alcohol with a metal, and observe for hydrogen gas bubbling.
How do you test between Primary, secondary and tertiary alcohols?
Oxidation, as tertiary alcohols do not undergo oxidation as it involves the breaking of a C-H bond.
Dichromate goes from orange to green.
Permanganate goes from purple to colourless.
How do you test for carboxylic acids?
NaHCO3 (Sodium Bicarbonate) test will produce CO2.
What is saponification?
The cleaving of esters into soaps and alcohols.
What is a polymer?
A large molecule made up of monomers, which can be joined together either through addition or condensation.
What is an addition polymer?
When unsaturated monomers join together, they are called addition polymers. No byproducts are formed.
How are polymers formed?
If done through high pressures and temperatures, low-density polyethene is created, named because of its branches.
If done through lower pressure and using a Zieger-Natta catalyst, the High-density polyethene will be formed, with less branches.
What is a condensation polymer?
Formed through condensation reactions, normally creating a byproduct of water.
What is vulcanisation?
Heating rubber with sulfur to make it more durable.
What are plasticisers?
Small molecules force polymers further apart, weaking the dispersion forces and making the polymers softer and more flexible.
What is PVC?
Polychloroethene is similar to polyethene, but with one of the hydrogens being replaced for a chlorine atom. The electronegativity of the chlorine results in dipole-dipole intermolecular forces being formed in PVC, much stronger than dispersion forces and resulting in a more more durable polymer.
What is a polyamide?
A condensation polymer linked by the amide functional group. One example is polypeptide. Requires an amine and carboxyl group.
What is polystyrene?
Made up of the monomer styrene, which has a benzene ring. The size of the benzene ring reduces stacking efficiency of polystyrene, making it less dense, hard and brittle.
What is polyester?
A condensation polymer that requires carboxyl groups and hydroxyl groups.
What is a forked shape in the Infrared spectroscopy at around 3000?
Aldehyde
And also density formula
mass = density x volume
How is purification done during esterification?
Reflux uses a condenser which cools done evaporating vapours to prevent loss of reactants.
Adding distilled water to the solution after the reflux will dissolve all of the polar components (water, sulfuric acid, alcohols, very short carboxylic acids).
The layer remaining is non-polar (esters, carboxylic acids.
Add sodium carbonate, which reacts with acids to create CO2, water and a sodium salt. CO2 leaves through the funnel while water and sodium salt can be discarded using separatory funnel.
