Intro to organic chem + isomerism Flashcards
(28 cards)
Primary vs Secondary vs Tertiary (how to identify?)
Based on no. of alkyl groups bonded to the C bonded to the functional group
Functional group isomerism examples
Aldehydes and ketones
Ethers and alchohols
Esters and Carboxylic acids
Types of isomerism
Constitutional - chain, positional, functional group
Stereoisomerism - cis-trans, enatiomerism
Why does cis-trans isomerism occur?
Free rotation restricted by presence of double bond, ring structure or steric factors
In Alkene, because of pi bond which restricts rotation about C=C double bond
Stereoisomerism definition
same molecular and constitutional formulaw but different 3D arrangement
Do cyclic alkenes experience cis trans?
No. 3-7 C in cis structure, 8 and above in trans structure because high ring strain
Why can cis trans isomers be isolated as 2 different compounds?
Restricted rotation about the single bonds in the cyclic systems
Chiral + Enatiomers definition/conditions
Chiral compound does not have an internal plane of symmetry nor a superimposable mirror image. Chiral molecule + non-superimposable mirror image form a pair of enatiomers
Physical vs chemical properties of cis trans isomers
Chemical properties similar, not identical (react with same reagents but at different rates)
Physical properties different
Racemic mixtures
Sample containing equal amounts of 2 enatiomers. Rotation of the 2 enatiomers are of the same extent but in opposite directions, causing no net effect on the plane-polarised light and hence optically inactive
Empirical formula
Simplest ratio of atoms of dif elements
Molecular formula
actual number of atoms of each element present in one molecule
Constitutional (skeletal) fomula
shows how constituent atoms are joined together
Displayed formula
shows arrangements of atoms and all the bonds between them
Stereochemical formula
spatial arrrangement of the molecule in a 3d space
functional group
an element/combination of elements responsible for the chemical reactions of an organic compound
Homologous series
Family of compounds containing the same functional group but differing by a CH2 group between one member and the next
Names and structures of all the dif functional groups
Hydrocarbons- alkanes, alkenes, alkynes, arenes
Hydroxyl- alchohol, phenol, ether
Halogen derivitives - halogenoalkanes, halogenoarenes
Carbonyls- aldehydes, ketones
Carboxylic acids and derivitives- carboxylic acid, ester, acyl chloride
Nitrogen compounds- amine, amides, nitriles, amino acids
Saturated vs unsaturated compound
saturated: only single bonds
unsaturated: multiple bonds
Explain hybridisation
One 2s electron is promoted to a 2p orbital, allows them to interact to form sp3, sp2 and sp bonds which are stronger and equal in length
Why use hybridisation?
equal bond length
More effective orbital overlap since larger lobe is used –> stronger bonds compared to if s orbitals or p orbitals overlap
sp, sp2 or sp3 strongest bond? Why?
sp. Highest degree of s character. Electrons held closer to the nucleus and shorter bond length–> stronger
How to figure out which hybrisation?
No of molecules it is bonded to + no of LP
sum = 4, sp3
sum = 3, sp2
sum = 2, sp
Types of organic reaction
Addition (formation of a pi bond)
Substitution (a group is replaced by another group of atoms)
Elimination (removal of atoms from 2 adjacent atoms (in one molecule) to form a pi bond)
Condensation (2 or more molecules combine to form a larger molecule and elminate a smaller molecule like water or HCl)
Hydrolysis: reaction with water, catalysed by acids/bases
Oxidation: gain O or lose H
Reduction: gain H or lose O
