introduction to organic chemistry Flashcards
what is a functional group and examples (alkane and alkene)
particular atoms or a group of atoms within an organic molecule, that define the physical properties and chemistry of that compound
alkane: NA
alkene: C=C
what are the degrees of substitutions and draw them out
primary, secondary, tertiary
what is the difference between empirical formula, molecular formula, structural formula, displayed formula, skeletal formula and stereochemical formula
empirical: simplest ratio (CH2O)
molecular: actual number of atoms (C3H6O3)
structural formula: shows how the atoms of a molecule are joined together with minimal detail (CH3CH(OH)CO2H)
displayed formula: detailed structure of molecule showing the relative placing of atoms and all the bonds between them (drawing)
skeletal formula: no hydrogen and hydrogen bonds, no carbon atoms
stereochemical formula: shows the 3D spatial arrangement of bonds, solid wedges indicate bonds pointing out of the plane of the paper towards you, dashed wedges indicate bonds pointing into the plane of the paper away from you and lines indicate bonds in the plane of the paper.
Nomenclature: stem from 1 to 10
meth, eth, prop, but, pent, hex, hept, oct, non, dec
Nomenclature: type of carbon-carbon bonds present in the longest carbon chain
-an: all C-C
-en: one C=C
-dien: two C=C
-trien: three C=C
-yn: one C≡C
different types of organic reactions
substitution
addition
elimination
condensation
hydrolysis
oxidation
reduction
what is substitution
when one atom or group of atoms replaces another atom or group in a molecule
what is elimination
when a C=C is formed with the removal of a molecule
what is addition
when an organic molecule (usually C=C) reacts with another molecule to give only one product. pi bond of double bond breaks to form two new sigma bonds
what is condensation
when two molecules come together to form a bigger molecule, with the elimination of a small molecule like water
what is hydrolysis
when a molecule is split into two by the action of water, often catalysed by dilute acids or dilute alkalis
what is oxidation
when O atoms are added to the molecule / when H atoms are removed from the molecule
what is reduction
when O atoms are removed from the molecule / when H atoms are added to the molecule
electrophile definition (lewis acids)
a species that accepts an electron pair to form a covalent bond in a reaction. it is electron-deficient due to having:
- a positively-charged center
- an induced or permanent partial positive charge (dipole molecules)
nucleophile definition (lewis bases)
a species that donates an electron pair to form a covalent bond in a reaction. it is electron-rich and possesses electrons that can be shared, such as
- long pairs of electrons
- pi bond (ethene)
factors affecting organic reactivities
inductive effect
delocalisation
steric effect (not an electronic effect)
what is the inductive effect
occus via sigma bonds and due to the difference in electronegativity between atoms in covalent bonds. gets weaker with distance
what is delocalisation
occurs due to 3 or more p orbitals overlapping, forming a pi electron cloud. it is independent of distance. the pi electrons in the two C=C bonds are delocalised throughout the pi electron cloud and not just localised at their respective double bonds. the C-C bond has partial double character and is somewhat stronger and shorter than a C-C single bond.
what is the steric effect
the larger the groups and the greater the number of groups crowding around the site of reaction, the greater the steric hindrance.
the steric effect is a result from the repulsion between electron clouds of groups of substituents, depending on their size and number. molecules with bulky substituents crowded around their reactive sites would hinder the approach of the other reactant for an effective collision.
what is homolytic fission
breaking of a covalent bond where the bonding pair of electrons are given equally to each atom. results in the formation of free radicals
what is heterolytic fission
breaking of a covalent bond where both bonding electrons are given one of the atoms, usually the more electronegative one. results in the formation of ions
what are carbocations?
species containing a positively-charged carbo atom, which has only six electrons in its outer shell. (due to a more electronegative element, like Cl)
what are carbanions?
species containing negatively charged carbon atom, which has a full octet of electrons in its outer shell.
