Organic Chemistry Flashcards
F Wohler synthesized organic compound:
NH4CNO –>NH2CONH2
(Ammonium–>(urea)
cyanate)
Functional groups in decreasing order
(-COOH),(-SO3H),(-COOR),(COCl),(-CONH2),(-CN),(-HC=O),(>C=O),(-OH),(-NH2),(>C=C<),-(C≡C-)
The size of the hybrid orbital decreases as
percentage of s-character increases
EN of the Hybrid Orbital is
sp > sp2 > sp3
Breaking of Bonds:
Homolytic fission & heterolytic fission
Homolytic Fission or Homolytic Cleavage
Each atom separates with 1 e’ in this type of bond breaking, resulting in formation of free radicals
Two half-headed or fishhook arrows represent bond breaking. 1 e’s movement is depicted by a half-headed arrow. Radicals are odd electron species that are neutral.
Heterolytic Fission or Homolytic Cleavage
Shared pair of e’s are transferred to more electronegative part. As a result, a cation and an anion are formed (ion-pair).
A full-headed arrow represents the bond breaking & depicts the movement of two e’s.
e’ movement is always represented by curved arrows, either half-headed or full-headed.
Inductive Effect:
When two unlike atoms form a covalent bond, the e’ pair that forms sigma bond is shifted slightly towards more electronegative species.
Electron Donating and Electron withdrawing Groups have ___ Inductive effect
+I and -I effect
Applications of Inductive Effect
- EWG raises acidic strength decreasing basic strength
- I.E decreases as the ERG/EWG moves away
resonance?
delocalization of electrons(pi electrons)
isomerism types
Structural: Occurs due to different structural arrangement of atoms of a compound with same chemical formula
Stereoisomerism: Same chemical formula and bond sequence but different 3D orientation of atoms in space. It is of two types- Geometrical and Optical
electrophiles & nucleophiles
Electrophiles: electron seeking
Nucleophiles: provide electron pairs or ‘nucleus seeking’
carbocations & carbanions
Carbocations are carbon intermediates with a positive charge and have 6 e’s in the valence shell. It has sp² hybridization.
Carbanions are carbon intermediates with a negative charge. They have 8 e’s in the outermost shell. Their hybridization is sp³.
free radicals
Carbon-free radicals are intermediates with odd e’s. They are neutral and have 7 e’s in the valence shell and have sp²
Resonance or Mesomeric Effect:
When the structure of a molecule cannot be explained explicitly in a single Lewis dot structure then a number of structures are required to show the structure of the molecule. This occurs because of the delocalization of pi electrons
Hyperconjugation Effect:
Ability of the sigma bond e’s of an alpha-carbon to form conjugation with adjacent pi e’s
Electromeric Effect:
Shifting of e’ pairs towards more electronegative atoms in a double-bonded system in presence of a reagent.
Methods of Purification of Organic Compounds
Crystallization
Sublimation
Fractional Distillation
Simple Distillation
Chromatography
Simple Crystallization:
In this process, a solvent is selected for preparation of a solution in which one of the elements crystallizes out in the form of a compound.
Sublimation:
Used for purifying relatively volatile organic solids
Fractional Distillation:
Used for purification of two substances with less difference in boiling points
Simple Distillation:
In this process, liquid is converted into vapour and vapour is transferred to another place and recovered by condensation.
Chromatography
In this process, the mixture is passed through a solution or suspension where it has different rates of moving. Types are adsorption & partition
Adsorption chromatography types:
column:separaton of a mixture over a column of adsorbent in a glass tube
thin layer:separation of a mixture over a thin layer of adsorbent on glass plate
