stereochemistry

Question 1

what is an isomer

Answer 1

compound with same molecular formular but different arrangement of atoms

Question 1

what are stereoisomers

Answer 1

compounds with the same molecular formular but different orientation

Question 2

what is the hybridisation of an alkyne and the shape of it

Answer 2

sp1, linear

Question 3

what is the hybridisation of an alkene and the shape of it

Answer 3

sp2, trigonal

Question 4

what is the hybridisation of an alkane

Answer 4

sp3

Question 5

two types of stereoisomers

Answer 5

conformational and configurational

Question 6

explain the two stereoisomers

Answer 6

conformational- interconvert easily through rotation around a single bond, ring flip

configurational- identical groups differ in how they arranged around central carbon, dont easily convert, bond needs to break in order to interconvert

Question 7

how to draw enantiomers of a molecule

Answer 7

draw the mirror image or draw the groups in the opposite orientation

Question 8

what is the enantiomer for 1S2R

Answer 8

1R2S

Question 9

what are the diastereoisomers for 1S2R and state which one is 2- or 1- epimer

Answer 9

2- epimer 1S2S and 1- epimer 1R2R

Question 10

what are meso compounds

Answer 10

group around centre is symmetrical, molecule can be rotated to make the compounds the same, plane of symmetry, optically inactive

Question 11

properties of enantiomers

Answer 11

chemically identical except optical properties, biological properties may be different

Question 12

properties of diastereoisomers

Answer 12

different physical and chemical properties

Question 13

what is optical activity

Answer 13

ability of a compound to rotate the plan of a polarized light

Question 14

describe the optical activity of enantiomers

Answer 14

enantiomers rotate plane polarised light in opposite directions, equal and opposite optical rotations

Question 15

what is dextrorotatory and laevorotatory

Answer 15

dextrorotary= + = plane rotated clockwise

laevorotatory= - = plane rotated anticlockwise

Question 16

what is dextrorotary

Answer 16

clockwise

Question 17

what is laevorotary

Answer 17

anticlockwise

Question 18

what is a racemic mixture/racemate

Answer 18

equal mixture of enantiomers

Question 19

physical properties of enantiomers and racemates

Answer 19

melting points of enantiomers are the same, different for racemates, physical properties are the same except for optical rotation, different pharmacological properties

Question 20

describe the melting points of enantiomers and racemates

Answer 20

the melting points of enantiomers are the same but racemate melting points are different

Question 21

how to measure polarimetric measurements

Answer 21

in a polarimeter

Question 22

what is in a polarimeter

Answer 22

single wavelength monochromatic light source, plane polarising filter, sample holder, detector

Question 23

what does alpha depend on in a polarimeter

Answer 23

path length, concentration, solvent, temperature, wavelength

Question 24

what are optical rotations measured at

Answer 24

20 c in a solvent like ethanol and the light used is the D line of a sodium lamp with a wavelength of 589 nm

Question 25

what is observed rotation

Answer 25

rotation of a compound observed in a polarimeter

Question 26

what is specific rotation

Answer 26

measured under specific conditions