Organic Chemistry Flashcards
what is the number of covalent bonds an element forms determined by?
the number of electrons in its outer shell
what does the reactivity of a molecule derive from?
functional groups
what are the four groups of functional groups?
hydrocarbons
functional groups containing oxygen
functional groups containing nitrogen
functional groups containing sulphur
what are the different types of hydrocarbons?
alkane
alkene
alkyne
aromatic
alkyl halide
what is the general structure of alkane?
c-c
what is the general structure of alkene?
c=c
what is the general structure of alkyne?
c(triple bond) c
what is the general structure of aromatic?
benzene
what is the general structure of alkyl halide?
h3c-X
what are the different types of functional groups containing oxygen?
alcohol
ether
aldehyde
ketone
carboxylic acid
acid chloride
acid anhydride
ester
what is the general structure of alcohol?
R-OH
what is the general structure of ether?
R-OR
what is the general structure of aldehyde?
RCHO
what is the general structure of ketone?
RCOR
what are the differnt groups in the functional groupd containing nitrogen?
amine
amide
nitrile
nitro
what is the general structure of carboxylic acid?
RCO2H
what is the general structure of acid chloride?
RCOCl
what is the general structure of acid anhydride?
(RCO)2O
what is the general structure of ester?
(RCO2R)
what is the general structure of amine?
RNH2
R2NH
R3N
R4N+
what is the general structure of amide?
RCONH2
what is the general structure of nitrile?
RCN
what is the general structure of nitro?
RNO2
what are the different functional groups containing sulphur?
thiol
thioether
what is the general structure of thiol?
R-SH
what is the general structure of thioether?
R-S-R
what is functional group interconversion?
the process that allow a synthetic chemist to transform a functional group into another to change molecular properties
how does the length of the chain effect the polarity of the molecule?
longer hydrocarbon= less polar
what are the four parts of the IUPAC naming of molecules?
prefix (substituents, other functionl groups, cyclic molecule)
parent (length of main chain)
infix (unsaturation of main chain)
suffix (dominant functional group+ position if needed)
what are the steps of systematic nomenclature IUPAC?
1) identify the longest carbon chain. this becomes the parent
2) identify unsaturation. chose the infix
3) number each carbon atom in the principal chain so that the group attached to the chain has the smallest possible number
4) name the substituent. this becomes the prefix to the principal chain. decide the suffix
what is stereochemistry?
the chemistry of molecules in three dimensions
what are structural isomers?
compounds with the same olecular ormula, but atoms are bonded in different orders
what are stereoisomers?
compounds with identical molecular formulae , atoms are bonded in the same order, but in a different spatial arrangment
what are the two major types of stereoisomers?
conformational isomers
configurational isomers
what are the types of configurational isomers?
optical isomers
geometrical isomers
what needs to be present for conformational isomers?
c-c
what are chiral molecules?
cannot be superimposed on their mirroe images
what are chiral carbons?
a carbon where four difffernt groups/ atoms are present
what is an achiral carbon?
at least 2 of the same groups/atom present
what type of isomer uses chiral carbons?
configurational isomers
what are enantiomers?
same physical/ chemical properties differ in activities with plane polarised light that give rise to optical isomerism, and also in their pharmacological actions
what is a racemic mixture?
a pair of enantiomers
50;50 ratio
when a polarised light passes through there is no rotation
what are the rules applied for designating any enantiomer to R or S?
1) priotity. from 1 to 4 assigned on the basis of atomic number. higher atomic number gets higher priority
2) substituents. if no priority, the next set of atoms in the unassigned group are examined
3) double or triple bonds assigned priorities as if both atoms were duplicated or triplicated
4) arrange the molecule so that group 4 is pointing away from the viewer
what are diastereosomers?
isomers of a compound that are nonidentical and that are no -identical and not mirror images of each other
what is the equation to find out how many possible stereoisomers there are in a drug?
2^n (where n= number of chiral centres)
what are geometric isomers?
stereoisomers that arise due to the restricted rotation within a molecule
only if two different groups at each ed of double bond
what are cis/trans nomenclature isomers?
two ends of the double bond have the same group attached
both ends of the double bond have two different groups attached
but groups at the end of double bond are idential to each other
trans=identical groups on different sides
cis=identical groups are on the same side
what are E/Z nomenclature isomers?
e= higher priority groups are on different sides
z=higher priority groups are on the same side
what are nucleophiles?
love nuclei
wish to form bonds by donating or shaing electrons
are electron rich and can be negative ions, or neutral molecules with electron lone pairs
what are electrophiles?
love electrons
wish to form onds by accepting electrons or sharing electrons with a reactant molecule
are electron deficeint and can be positive ions or negative molecules
what is a double headed arrow used to show?
the movement of a pair of electrons
what is a single headed arrow used to show?
the movement of a single electron
what are the alkyl halide reactions?
nucleophilic substitution
elimination reaction
what is nucleophilic substitution?
nucleophile replaces a leaving group from a carbon atom, using its lone pair of electrons to form a new bond to the carbon atom
what is an elimination reaction?
halide ion leaves along with another atom or ion, a new pi bond results
dehydrohalogenations
reagent reacts as a base
most nucleophiles are basic and can engage in either substitution or elimination, depending on the alkyl halide and the reaction conditions
what happens in a Sn2 reaction?
nucleophile approaches electrophile from the opposite side of the molecule to the leaving group
what is a transition state?
theoretical representation of the high energy point between starting materials and products. it does not physically exist
what is Sn2?
substitution nucleophilic bimolecular reaction
what is a bimolecular reaction?
two species are involved in the rate determining step (defined as the slowest step of a reaction)
what is the transition state in Sn2?
bond to nucleophile is partially formed and the bond to the leaving group is partially broken
what are the factors affecting Sn2 reaction(nucleophile)?
Strength of nucleophiles
strong nucleophile=react faster in a Sn2 reaction
1.species with a negative charge means that there is a stronger nucleophile than a similar neutral species
2. nucleophilicity decreses from left to right , following the increase in electroneativity
3. nucleophilicity increaases down , following the increase size and polarisability
Bulkiness of the nucleophiles
bulky groups on the nucleophile hinder the close approach which slows the reaction
Solvent effect on nucleophilicity
protic solvent=reduce nucleophilicity
aprotic solvents=enhance nucleophilicity
polar aprotic solvents= enhance solubility
what is basicity?
defined by the equilibrium constant for abstracting an acidic proton; forms a new bond to a proton, it has reacted as a base
what is nucleophilicity?
defined by the rate of attack on an electrophillic carbon atom; forms a new bond to carbon, it has reacted as a nucleophile
why can electrons form bonds at relatively long distances?
electrons are more loosely held, can move freely toward a positive charge resulting in stronger bonding enhancing the atoms ability to begin to form a bond at a relatively long distance
what are protic solvents?
OH/NH groups
H-bonds to negatively charged nucleophiles
very good in solubilising reagents
what are aprotic solvents?
without OH/NH group
anions are more reactive
relatively weak solvating ability