Chapter 11 Flashcards
What do all organic compounds have in common?
They all contain the element carbon
What is organic chemistry?
Chemistry of compounds derived from living systems
How are organic materials produced?
Through fractions of cruse oil
Why is carbon so special?
Group 14 - 6 atomic number (4 electrons in outer shell) and therefore can form up to 4 covalent bonds - single, double or triple and can bond to other carbons to create long chains and can bond to other atoms such as oxygen, nitrogen and halogens
What is a hydrocarbon?
Compound containing only hydrogen and carbon
What are saturated hydrocarbons?
Has single covalent bonds between the carbons
What is an unsaturated hydrocarbon?
Contains carbon-to-carbon multiple bonds (covalent)
What is a homologous series?
Family of compounds with similar chemical properties whose successive members differ by the addition of a -CH2- group (SAME FUNCTIONAL GROUP)
Alkanes
Single carbon to carbon bonds (CnH2n+2) ; methane CH4 + CH2 (ethane C2H6) + CH2 (propane C3H8)
Bond angle around carbon in alkane
Tetrahedral 109.5 degrees (no lone pairs)
What is a functional group?
Part of the organic molecule that is largely responsible for the molecule’s chemical properties - carbon can bond to other elements (nitrogen, halogens, oxygen etc) that forms other functional groups
Amine functional group
NH2
Alcohol functional group
OH
IUPAC
Organisation who recognised need for standardisation of the names of compounds - allows chemists across the globe to communicate clearly
Aliphatic hydrocarbons
CARBON ATOMS are joined to each other in unbranched (straight) or branched or non-aromatic rings (THIS IS REFERRED AS ALICYCLIC)
Alicyclic hydrocarbons
CARBON ATOMS joined together in ring structure with or without branches - TYPE OF ALIPHATIC HYDROCARBONS
Aromatic hydrocarbons
SOME/ALL OF CARBON ATOMS found in a benzene ring - special class (all other rings are aliphatic and alicyclic)
3 homologous series of aliphatic hydrocarbons
Alkanes (single C-C bond)
Alkenes (C=C bond)
Alkynes (at least 1 triple C C bond)
Stem, prefix and suffix
Stem - longest continuous chain in molecule
Prefix - added before chain (presence of side chain)
Suffix - indicates functional group
How to name an aliphatic alkane?
Suffix = “ane”
Identify parent chain (longest chain)
Identify any side chains - alkyl groups have one hydrogen atom removed from the parent chain - THIS IS PREFIX
Add numbers before alkyl group to indicate position
When two or more side chains are added…
di- (2)
tri- (3)
tetra- (4)
What if there are two or more possible chains of same length?
CHAIN WITH MOST BRANCHES
How to order numbers?
Position - alkyl group
Use comma to separate numbers
Alkyl groups are ordered alphabetically (ethyl before methyl)
How to name alicyclic alkanes?
Same as aliphatic alkanes but prefix cyclo- in front of stem is used to show that carbons are arranged in a ring structure
Difference between naming alkenes and alkanes?
Suffix is ene and position of C=C bond in the chain MUST BE STATED FOR ALKENES THAT HAVE 4 OR MORE CARBON ATOMS IN LONGEST CHAIN
How to name alkenes?
Identify the suffix (ene)
Look at stem parent chain
Look at where double bond is between - lowest number is used
Combine stem+position+suffix for final hydrocarbon
What if there are two groups coming off one carbon in parent chain?
The Carbon is by itself
If there was one group it would be CH
How to write structural formula of 3-methylhex-2-ene?
MAKE SURE THAT DOUBLE BOND IS CONNECTED TO CH NOT CH2 (ALWAYS CHECK IF CARBON HAS A VALENCY OF 4)
How to number alkyl groups on alicyclic compounds?
Lowest numbers - start from the double bond if alkene (give that the lowest number)
Does the “di/tri” part take part in alphabetical ordering?
NO ONLY THE ACTUAL GROUPS
Alkene functional group
C=C (suffix is ene)
Alcohol functional group
-OH (hydroxyl prefix and -ol suffix)
Haloalkane functional group
-cl, -br, -I (chloro/bromo/iodo prefixes)
Aldehyde functional group
H-C=O (CHO - suffix is “al”)
Ketone functional group
-C(C=O)C-
O attached to C double bond with 2 single carbon bonds to central C
Ends in one
Carboxylic acid functional group
-COOH (ending in oic acid)
Ester
-COOC-
Central C atom double bond with O and single bond with O attached to C
Ends in “oate”
Acyl chloride
COCl
Central C double bond to O and single bond to Cl
Ends in oyl chloride
Amine functional group
NH2 ends in amine and starts with amino
Nitrile functional group
CN - ends in nitrile
How do we number functional group?
Butan-2-ol for example (where OH is on second carbon)
Aldehydes
DO NOT NEED NUMBERS TO SHOW POSITION OF CARBONYL (H-C=O) GROUP
THE CARBON ON ALDEHYDE IS AUTOMATICALLY NUMBERED AS 1
Displayed formulae
Every atom and bond shown to give a clear picture of how atoms are bonded
Molecular formula
Shows the number and type of each element present in a molecule - DOES NOT SHOW HOW ATOMS ARE JOINED TOGETHER ; different molecules can have the same molecular formula
Ethanol molecular formula = C2H6O
Empirical formula
Simplest whole number ratio of atoms of each element present in a compound
Alkenes (CH2)
Glucose empirical formula is CH2O
What is the general formula?
Simplest algebraic formula for any member of a homologous series ; can be used to GENERATE THE MOLECULAR FORMULA
General formula for alkanes?
CnH2n+2
General formula for alcohols
CnH2n+1OH
General formula of carboxylic acids
CnH2nO2
Ketone general formula
CnH2nO (Look at propanone)
Difference between general and molecular formula for alcohols?
GENERAL FORMULA IS CnH2n+1OH BUT MOLECULAR FORMULA IS CnH2n+2O
Carboxylic acid numbering
Always numbered 1 like with aldehydes
Displayed formula
Shows relative position of all atoms and bonds between them
Structural formula
Uses smallest amount of detail necessary to show arrangement of atoms in a molecule - shows clearly which groups are bonded together
Butane structural formula
CH3(CH2)2CH3
Molecules can have same molecular formula but…
Different structural formula
What detail do you remove in a skeletal formula?
All of the carbon and hydrogen labels and any bonds to hydrogen atoms
What does end of line in a skeletal formula represent?
CH3 group
How to represent alicyclic and aromatic compounds?
Draw shape and add any carbons in for alkene - benzene can be represented as ALTERNATING DOUBLE BONDS (AROMATIC) or with a circle within hexagon
Are functional groups included in skeletal formula?
YES THEY MUST BE SHOWN
Benzene formula
C6H6
Isomers
Different compounds with the same molecular formula
Structural isomers
Compounds with the same molecular formula but different structural formulae
C4H10 isomers
Butane and 2-methylpropane ; the molecular formula does not unambiguously identify the STRUCTURE
How are different isomers with functional groups arranged?
The functional group may be at different positions along the carbon chain
Isomers with different functional groups?
Sometimes two molecules containing different functional groups have the same molecular formula ; aldehydes and ketones (C3H6O)
What is a covalent bond?
Shared pair of electrons between two atoms - when chemical reaction occurs then bonds in the reactants break and new bonds form in the products ; can be broken through homolytic or heterolytic fission
Homolytic Fission
Each of the bonded atoms takes one of the shared pair of electrons from the bond - each atom now has a single unpaired electron and this atom/group of atoms is called a radical
Heterolytic fission
One of the bonded atom takes both of the electrons from the bond (this atom becomes a negative ion) and the atom that does not take electrons becomes a positive ion ; DEPENDENT ON WHICH IS MORE ELECTRONEGATIVE (δ- becomes the negative ion)
Reaction mechanisms
They show how the reaction takes place
Curly arrows
MOVEMENT OF ELECTROJ PAIRS - HETEROLYTIC
Fish hook arrow
MOVEMENT OF SINGLE ELECTRONS - HOMOLYTIC FISSION
Addition reaction
2 reactants join to form one product ; double bond is broken to form a single saturated compound
Substitution reactions
Atom or group of atoms is simply replaced by another group of atoms
Elimination reaction
1 reactant to 2 products
Often double bond I’d formed
Removal of a small molecule from a larger one
WHAT TO REMEMBER ABOUT RADICALS
Always PUT THEM ON ATOM WITH THE UNPAIRED ELECTRON
