Intro to Org Chem Flashcards
What is a fn group?
An atom or group of atoms common to series of org. compounds that effectively determines the principal chemical properties (Alkanes not counted, C counts from position of fn grp)
What is a homologous series?
It is a series of compounds w same fn grp & same general formula
What does R denote?
Alkyl grp (methyl ethyl etc. beyond ethyl cannot show condensed formula)
Cn H2n+1
2 types of stereoisomers?
Cis-trans
Enantiomers
Criteria for cis trans
Restricted rotation around C=C
2 diff substituents attached to each C atom in C=C
CYCLIC does not show cis trans, ring would be distorted, results in considerable ring strain -> instability
Physical & chemical properties of Cis trans isomers
Similar chemical
Diff physical
Reason 1: (cis higher bp)
Cis -> polar due to net dipole moment
Trans non polar due to no net dipole
Cis -> Higher amt energy req. to overcome stronger pdpd betw. polar cis vs weaker idid in non polar trans
Reason 2: (Trans higher MP*)
- Trans has more SYMMETRICAL & LINEAR shape -> CLOSER PACKING of molecules in SOLID state, more extensive intermolecular FOA
Criteria for enantiomerism
Chiral -> 4 diff atoms/groups
- Non superimposable mirror image
- at least 1 chiral C
- No plane of SYMMETRY
Properties of enantiomers
Optically active in plane of polarised light
Identical chemical properties except
interactions w other chiral molecules
Identical physical properties except rotation in plane polarised light
What is a racemic mixture?
Mixture containing equal amt of each enantiomer
Optically inactive, no net rotation in plane polarised light, rotation is cancelled by other enantiomer
(Molecule w equal amt of chiral C with + & - enantiomer also cancels out)
What is hybridisation?
Mixing of atomic orbitals in an atom to generate new set of orbitals called hybrid orbitals
sp3?
4 sigma
1s 3p
All head on overlap
tetrahedral, 109.5
sp2?
3 sigma
1s & 2p
head on & side on
Trigonal planar 120
sp?
2 sigma
1s & 1p
linear 180
What is an electrophile?
Electron deficient, lewis acid acceptor
lone pair acceptor
Anion, δ-
What is a nucleophile?
Electron rich,
Lewis base
Lone pair donor
attracted to e- deficient regions
Cation δ+
What is a free radical?
A species with an unpaired e- electrically neutral, v reactive
Types of covalent bond cleavage/fission
Homolytic fission
- Half headed arrow, each atom gets 1e-
- Forms radicals
Heterolytic fission
- Full arrow, both e- (pair) go to 1 atom
- Forms ions
What are the 7 rxns in org chem?
- Addition
- Substitution
- Elimination
- Condensation
- Hydrolysis
- Redox
- Neutralisation
