Introduction to Organic Chemistry

Question 1

how can organic compounds be represented?

Answer 1

• empirical formula
• molecular formula
• general formula
• structural formula
• displayed formula
• skeletal formula

Question 2

empirical formula definition

Answer 2

simplest whole number ratio of the elements in a compound

Question 3

molecular formula definition

Answer 3

actual number of atoms of each element in a compound

Question 4

general formula definition

Answer 4

used to work out the formula in any compound of a homologous series

Question 5

structural formula definition

Answer 5

simplified version of displayed formula (shows groups of atoms)

Question 6

displayed formula definition

Answer 6

shows every bond+atom in a compound

Question 7

skeletal formula definition

Answer 7

a formula that leaves out C-H bonds but representes them as lines

Question 8

homologous series

Answer 8

• have same functional groups
• react similarly
• each member differs from the rest by CH2

Question 9

IUPAC rules for nomenclature

Answer 9

• find length of the longest carbon chain.
• find functional groups=reactive part of molecule
• ensure carbon with fncy=tional group has lowest no
• determine suffix/preffic
• adapt for any double/triple chains

Question 10

reaction mechanisms
(free radical substitution)

Answer 10

• 3 steps
  Initiation
  Propagation
  Termination
• Initiation
  *Under UV light chlorine gas molecules (Cl2) break apart homolytically to form chlorine free radicals (O)
• This is another example is homolytic fission
• Chlorine free radicals = chlorine atoms.
• The Cl-Cl bonds are weaker so they break girst:
  Cl2 → CI+ CI or 2 Cl*
• Propagation
• The chlorine free radical now reacts with methane molecule stripping any hydrogen atom forming HCl a methyl free radical
  CH4 + CI* → * CH3+HCl
• methyl Iradical then reacts with another chlorine molecule to form chloromethane and regenerates another chlorine free radical.
• CH3 + C2 → CHCl+ CI°
• These reactions are self propagating (they will keep going until they runout pf a reactant)
  Termination
• This involves any teo greeradicas species sormed doning the process combining together.
• There arez of these toworn out.
• Ci. +Cl: → C12 (no marks in examtno)
• *CI+ CH3 → CHzA (generates productwewant)
• ” CH3 + *СН3 → C2H6 (ethane=uncanted Dyproduct)
• Thesefermination steps since they use up free-radicus and lead to the reaction slowing istopping.
  -Nothing stops chloromethane gromreading withother
  chlorine greeradicals = by-productseg. CH20/2. CHA3,
  CC are gormed.
• I this by meeping amount of methane in excess.

Question 11

other reaction mechanisms

Answer 11

• covalent bond forming
  Curly arrow starts from a lone electron pair or from another covalent bond
• covalent bond breaking
  Curly arrow starting from the bond.

Question 12

Types of isomerism

Answer 12

Structural - same atoms but diff connections
Stereoisomers - connected in the same way but have diff spatial arrangement of atoms

Question 13

Types of structural isomers

Answer 13

Chain=diff carbon skeleton arrangement (branched vs straight chain)
Positional=functional grp is attached at diff C atoms
Functional grp=atoms form diff functional grp

Question 14

Types of stereoisomers

Answer 14

• Geometric (E/Z)
  E-isomer=high priority grps are diagonal form each other across the C=C
  Z-isomer=high priority grps are on the same side of C=C
  Use Cahn-Ingold-Prelog priority rules to assign priority to groups bonded to each carbon of the double bond=higher atomic no=higher pri
  Optical
• molecule must have a chiral centre=bonded to 4 other atoms
• non-superimposable mirror image forms=enantiomers=show diff reactions w plane-polarised light