Organic I Flashcards
method for finding isomers for an alkene
label each C group according to groups attached
count all possible different adjacent pairs, a-b = b-a
this is the number of possible isomers
define constitutional isomer
same molecular formula, different structural formula
define conformational stereoisomer
can be interconverted without breaking bonds
free rotation about C-C bond
sufficient energy at room temp to rapidly interconvert
eg. butane, rotation about C2-C3
why do double bonds restrict rotation?
double bonds have 1 sigma, 1 pi bond
e- in pi bonds are ‘above’ and ‘below’ the axis of rotation
on rotation, p-p overlap reduced to 0
this bond breaking requires more energy than available at room temp
define E-Z
assign priorities
higher priority on the Same side = Z
Opposite = E
amide functional group and naming
CONH2
with double bond O from C
-amide
aldehyde functional group and name
-CHO
O double bonded to C, an end Carbon
-al
ketone functional group and name
C=O not at terminal C
-one
Ester functional group and name
RCO2R
double bond O
-oate
The chain with the double bonded O is the main, the other branch is the -yl group
ether functional group
R-OR
acyl chloride functional group and name
RCOCl
one C=O
-oyl chloride
nitrile functional group
RCN
C triple bonded to N
what groups take priority in numbering of chains?
the amide, aldehyde and carboxylic acid functional groups (all terminal)
formula of the phenyl substituent
C6H5
what are the 3 pairs of functional group isomers?
CnH(2n)O2: esters, RCOOR’, and carboxylic acids, RCOOH
CnH(2n+2)H: ethers, ROR, and alcohols, ROH
CnH(2n)O: ketones and aldehydes
what are the carboxylic acid derivatives?
carboxylic acid, acidic H swapped –> ester
-OR’ of ester swapped for NH2, –> amide
swapped for Cl –> acyl chloride
systematically drawing isomers
start with linear branches then consider chains from shortest to longest
place functional groups on DIFFERENT atoms
monovalent (OH, Cl) replace 1H
divalent (=O) replaces 2H
split chains into 2 parts for esters and ethers
(eg. 5C –> 1C and 4C, or 2C and 3C)
amino acid group
compounds with amine and carbonyl
-NH2 and =O
what element has the lowest electronegativity of common organic elements?
H
hence O-H is very polar (high e- density)
e- density at O singly bonded vs doubly bonded to C
e- density at O singly bonded is LOWER than O doubly bonded
C-O < C=O
what are temporary intermolecular forces?
induced temporary dipoles: attractive forces due to temporary distortion of e- clouds when molecules approach each other from any direction
larger C chain = larger attractive force = higher bp
what organic compounds have hydrogen bonding?
where N-H or O-H bonds are present
alcohols, carboxylic acids, amines, amides
what organic molecules have permanent dipoles?
=O group
ketones, aldehydes …
what is halogenation of alkanes?
possible products?
making haloalkanes by reacting halogen with alkane is the presence of UV light
hydrocarbon in excess, only 1 X substituted
Halogen in excess –> polyhalogenated product, mixture of products
alkenes to alkanes reaction
platinum (Pt) or palladium (Pd) catalyst
react alkenes with H2
catalyst required as H-H strong
slow addition reaction
how does a catalyst in alkene –> alkane work?
catalyst forms a complex w/ H2 to activate it
H-H broken by binding to Pd surface, then transferred to alkene
reaction of alkenes and HX or X2 and possible products
occurs rapidly at room temp, no UV
atoms added across double bond due to higher reactivity
if either alkene OR reagent is symmetrical, only one possible product
both asymmetric, 2 products, by Markovnikoff’s
markovnikoff’s rule
rule for addition
rich get richer
produces tertiary > secondary > primary
alkenes to alcohols reaction and products
- addition of conc H2SO4
- reaction of intermediate sulfate with H2O
2 alcohols produces by asymmetrical alkene, Markovnikoffs
oxidation in organic terms
reactions that result in C-H bonds being replaced with C-O bonds
traditionally, oxidations occur with O2 (combustion)
primary alcohol oxidation reactions
alcohols with an H at the C bearing O react w/ chromic acid (H2CrO4) or Cr2O7^2-/H+ to give
–> aldehyde (1˚)
because aldehydes have H at the C bearing O, they are further oxidised in XS oxidant
–> carboxylic acid (1˚)
secondary alcohol oxidation reaction
reacts w/ H2CrO4 or acidified dichromate to make the ketone
ketone has no further H on C w/ O, does not further react
tertiary alcohol oxidation reaction
tertiary alcohols do not have H on the C bonded to O, so they cannot be further oxidised, they do not react w/ H2CrO4
regioselective define
formation of one POSITIONAL isomer over another
(reactions where a substrate capable of producing CONSTITUTIONALLY isomeric products gives only 1 or predominantly 1 of these)
eg. adding HBr to asymmetric alkene
use Markovnikoff’s
define stereospecific
when a pair of enantiomers are produced, one stereoisomer is favoured over the other.
(where one particular stereoisomer of the substrate gives one specific stereoisomer of the product )
eg. bromination, catalytic hydrogenation
how to find oxidation level at a C in an organic compound
pi bonds to another C + # bonds to oxygen
