Chirality And Carbonyls

Question 1

Optical isomers

Answer 1

4 different groups on a C
Mirror image but not super imposable

Question 2

Chiral

Answer 2

Atom in molecule that exists as non-superimposable

Question 3

Asymmetric

Answer 3

C joined to 4 different groups

Question 4

Enantiomers

Answer 4

Pair of molecules that exist as optical isomers

Question 5

Polarised vs unpolarised light

Answer 5

Oscillations on one plane
Oscillations on any plane

Question 6

Polarimetry

Answer 6

Some fibres absorb all light expect one plane
Monochromatic light —> polariser
Polarised light —> sample tube
Plane rotates if optically active
2nd polarised rotated to max light intensity
Angle recorded
Unpolarised —> polarised

Question 7

Optical activity

Answer 7

Different directions of polarisation planes
CW +
ACW -

Question 8

Enantiomer physical properties

Answer 8

Identical
Expect PoP rotation

Question 9

Enantiomer chemical properties

Answer 9

Identical
Except reaction with other enantiomers

Question 10

Racemic mixture

Answer 10

Race mate
50:50 mix of enantiomers

Question 11

Drug industry and enantiomers

Answer 11

Optically active
Often 1 Enantiomer works
In/on cell receptor
Only 1 Enantiomer fits
Other could be dangerous
Separate, difficult, expensive
Sell, dangerous, wasteful
Alternative synthesis

Question 12

Aldehyde FG

Answer 12

RCHO
End of chain

Question 13

Aldehyde suffix

Answer 13

Al

Question 14

When are aldehydes formed

Answer 14

Oxidation of P alcohols

Question 15

Properties of aldehydes

Answer 15

Short chain - unpleasant smell, soluble (HB with water not each other)
Long chain - perfume
Alkanes < bp < ketones, acid, alcohol

Question 16

Properties of ketones

Answer 16

Short chain - solvents, soluble (HB with water not each other)
Alkanes, aldehydes < bp < acid, alcohol

Question 17

Carbonyls

Answer 17

C=O
Aldehydes/ketones
Nucleophilic addition
Electronegative
Nucleophile attacks C*+

Question 18

Bonding and properties of carbonyls

Answer 18

Polar/permanent dipole
Very strong
Sigma and pi bonding
High electron density around O

Question 19

Oxidation test A VS K

Answer 19

Acidified potassium dichromate, water bath,
Aldehyde: O (6+)—> G (3+), A —> CA
Ketone: no change

Question 20

Fehling’s/Benedict’s solution A VS K

Answer 20

Water bath
Aldehyde: deep blue solution (11+) —> brick red ptte (1+), A —> CA
Ketone: no change

Question 21

Tollen’s solution A VS K

Answer 21

V hot water bath
Aldehyde: colourless (red 1+) —> silver mirror (solid Ag)
Ketone: no change

Question 22

Reduction A VS K

Answer 22

H- nucelophile
LiAlH4
Lithium aluminium hydride
Dry + acid, no water, powerful, reacts with water, flames

Question 23

A VS K iodine reactions

Answer 23

Yellow insoluble solid, CHI3
Alkaline solution, warmed, pooled
Ethanol, Propan2ol, butan2ol give positive results and carbonyls
3 H in CH3 substituted with I using OH-
Carbonyl + I2 + OH- —> CHI3 + RCOO- + I- + H2O
CI3 bond broken triiodomethane and acid salt

Question 24

Brady’s reagant A VS K

Answer 24

Most carbonyl compounds
Brightly coloured orange solid
Derivatives have different melting points
Makes a hydrazone
Purified, filtered, dried