Introduction To Organic Chemistry Flashcards
Empirical formula
Simplest ratio of atoms of each element in a compound (cancel numbers down if possible)
Molecular formula
Actual number of atoms of each element in a molecule
Structural formula?
Shows the atom carbon by carbon with attached hydrogen and functional groups
Skeletal formula?
Shows bonds of carbon Skeleton only with any functional groups. Hydrogen and carbon atoms aren’t shown. Handy for drawing large complicated structures like cyclic hydrocarbons
Displayed formula?
Shows how all the atoms are arranged and all the bonds between them
What’s a homologous series?
A group of compounds that contain the same functional group. Can all be represented by the same general formula
What’s a functional group
Reactive part of molecule gives most of its chemical properties
Alkenes
-ane
Propane
Branched alkanes
Alkyl-
Methylpropane
Alkenes
-ene
Propene
Halogenalkanes
Fluoro
Chloro
Bromo
Iodo
Alcohols
-ol
Aldehydes
-al
Ketones
-one
Carboxylic acid
-oic acid
Ester
Alkyl-
-oate
Amines
-amine
Amides
-amides
Acyl chlorides
-oyl chloride
Cycloalkanes
Cyclo-
-ane
Arenes
-benzene
Phenyl-
1 carbon
Meth
2 carbons
Eth
3 carbons
Prop-
4 carbons
But-
5 carbons
Pent-
6 carbons
Hex-
What will the main functional group of the molecule usually give you?
The end of the name (suffix)
What might the longest carbon chain?
Bent but count it as through it were straight
How do deal with the side branches or less important functional groups?
Added as prefixes at start of the name.
Put them alphabetically order with number of carbon atoms each is attached to.
What happens if there is more then 1 identical side chain or functional group?
Use di
Tri
Tetra
Ignore this when alphabetically ordering them
General formula?
An algebraic formula that can describe any member of a family of compounds
What is the IUPAC system ?
It’s an agreed international language of chemistry. Years ago, organic compounds were given whatever names people fancied, such as acetic acid and ethylene but these names caused confusion between different countries.
Why is the IUPAC so important?
Means scientific ideas can be communicated across the globe effectively. So it’s easier for scientists to get on with testing each other’s work and either confirm or dispute theories
What are mechanisms?
Diagrams that break reactions down into individual stages. They show how molecules react together by using curly arrows to show which bonds are made of broken
Curly arrow?
Starts at bond or lone pair where electrons are at the beginning of the reaction
Arrow points to where new bonds are formed at the end of the reaction
One point on the arrow means one electron
Two points on the arrow means pair of electrons
When are two molecules isomers?
If they have the same molecular formula but the atoms are arranged differently
Two types of isomerism?
Structural isomerism
Stereoisomers
What are the atoms in structural isomers like?
They are connected in different ways
So have same molecular formula but different structural formula
Three types of structural isomers?
Chain isomers
Positional isomers
Functional group isomers
Chain isomers?
Chain isomers have different arrangements of the carbon skeleton. Some are straight chains and others branched in different ways
Positional isomers?
Positional isomers have the same skeleton and the same atoms or groups of atoms attached
Difference is that the group of atoms is attached to different carbon atoms
Functional group isomers?
Functional group isomers have the same atoms arranged into different functional groups
Stereoisomers?
Have the same structural formula but a different arrangement in space
Why does E/Z isomerism exist?
C=C double bond and atoms bonded to these carbons all lie in the same plane (planar)
C=C bonds can’t rotate around them like single bonds. Double bonds are fairly rigid so don’t bend.
Restricted rotation around C=C double bond causes E/Z isomerism
Can you turn isomers into another by rotating?
No
Where are alkenes movements restricted?
Around their carbon-carbon double bonds
Meaning that if both of the double-bond carbons have different atoms or groups attached to them, arrangement of those troupe around the double bond become important. You get two stereoisomers
Z-isomer
Same group either both above and below the double bond
E-isomer
Same groups positioned across the double bond
When things get complex how do you determine E/Z isomers?
Using Cahn-Ingold-Prelog rules
Assign priority to two atoms attached to each carbon in the double bond
Look at the atoms directly bonded to each of the C=C carbon atoms.
Atoms with higher atomic number on each carbon is given priority
To work out which isomer you have look at how the two higher priority groups are arranged
What may you have to do?
If the atoms are directly bonded to the carbon are the same then look at the next atom in the group to work which has higher priority
What will the naughty examiner sometimes do?
Make things that look like an isomer but isn’t
so if you can switch between two drawings of a molecule either by rotating c-c single bonds or rotating the entire molecule you’ve drawn the same isomer twice
