Organic I

Question 1

method for finding isomers for an alkene

Answer 1

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

Question 2

define constitutional isomer

Answer 2

same molecular formula, different structural formula

Question 3

define conformational stereoisomer

Answer 3

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

Question 4

why do double bonds restrict rotation?

Answer 4

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

Question 5

define E-Z

Answer 5

assign priorities
higher priority on the Same side = Z
Opposite = E

Question 6

amide functional group and naming

Answer 6

CONH2
with double bond O from C

-amide

Question 7

aldehyde functional group and name

Answer 7

-CHO
O double bonded to C, an end Carbon

-al

Question 8

ketone functional group and name

Answer 8

C=O not at terminal C

-one

Question 9

Ester functional group and name

Answer 9

RCO2R
double bond O

-oate
The chain with the double bonded O is the main, the other branch is the -yl group

Question 10

ether functional group

Answer 10

R-OR

Question 11

acyl chloride functional group and name

Answer 11

RCOCl
one C=O

-oyl chloride

Question 12

nitrile functional group

Answer 12

RCN

C triple bonded to N

Question 13

what groups take priority in numbering of chains?

Answer 13

the amide, aldehyde and carboxylic acid functional groups (all terminal)

Question 14

formula of the phenyl substituent

Answer 14

C6H5

Question 15

what are the 3 pairs of functional group isomers?

Answer 15

CnH(2n)O2: esters, RCOOR’, and carboxylic acids, RCOOH

CnH(2n+2)H: ethers, ROR, and alcohols, ROH

CnH(2n)O: ketones and aldehydes

Question 16

what are the carboxylic acid derivatives?

Answer 16

carboxylic acid, acidic H swapped –> ester

-OR’ of ester swapped for NH2, –> amide

swapped for Cl –> acyl chloride

Question 17

systematically drawing isomers

Answer 17

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)

Question 18

amino acid group

Answer 18

compounds with amine and carbonyl

-NH2 and =O

Question 19

what element has the lowest electronegativity of common organic elements?

Answer 19

H

hence O-H is very polar (high e- density)

Question 20

e- density at O singly bonded vs doubly bonded to C

Answer 20

e- density at O singly bonded is LOWER than O doubly bonded

C-O < C=O

Question 21

what are temporary intermolecular forces?

Answer 21

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

Question 22

what organic compounds have hydrogen bonding?

Answer 22

where N-H or O-H bonds are present

alcohols, carboxylic acids, amines, amides

Question 23

what organic molecules have permanent dipoles?

Answer 23

=O group

ketones, aldehydes …

Question 24

what is halogenation of alkanes?

possible products?

Answer 24

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

Question 25

alkenes to alkanes reaction

Answer 25

platinum (Pt) or palladium (Pd) catalyst
react alkenes with H2

catalyst required as H-H strong
slow addition reaction

Question 26

how does a catalyst in alkene –> alkane work?

Answer 26

catalyst forms a complex w/ H2 to activate it

H-H broken by binding to Pd surface, then transferred to alkene

Question 27

reaction of alkenes and HX or X2 and possible products

Answer 27

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

Question 28

markovnikoff’s rule

Answer 28

rule for addition
rich get richer

produces tertiary > secondary > primary

Question 29

alkenes to alcohols reaction and products

Answer 29

1. addition of conc H2SO4
2. reaction of intermediate sulfate with H2O

2 alcohols produces by asymmetrical alkene, Markovnikoffs

Question 30

oxidation in organic terms

Answer 30

reactions that result in C-H bonds being replaced with C-O bonds

traditionally, oxidations occur with O2 (combustion)

Question 31

primary alcohol oxidation reactions

Answer 31

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˚)

Question 32

secondary alcohol oxidation reaction

Answer 32

reacts w/ H2CrO4 or acidified dichromate to make the ketone

ketone has no further H on C w/ O, does not further react

Question 33

tertiary alcohol oxidation reaction

Answer 33

tertiary alcohols do not have H on the C bonded to O, so they cannot be further oxidised, they do not react w/ H2CrO4

Question 34

regioselective define

Answer 34

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

Question 35

define stereospecific

Answer 35

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

Question 36

how to find oxidation level at a C in an organic compound

Answer 36

pi bonds to another C + # bonds to oxygen