Isomerism and carobonyl compounds - organic

Question 1

What is optical isomerism

Answer 1

type of stereoisomerism
- have chiral carbon atoms

Question 2

Stereoisomerism

Answer 2

have same stu formula , but atoms arranged differently in space

Question 3

Chiral

Answer 3

carbon atom that has 4 different groups attached to it
- possi to arrange group in 2 diff way around the chiral carbon atom ( 2 mole made )
- enantiomers
- optical isomers

Question 4

what is enantiomers

Answer 4

mirror image
- can’t be superimposed ( can tell them apart )

Question 5

if mole = superimposed

Answer 5

achiral and there is no optical isomer

Question 6

drawing optical isomers

Answer 6

• find out the central chiral carbon
• draw one enantiomer in tetrahedral shape - just use stu f
• draw the mirror image of the enantiomer

Question 7

Optical activity

Answer 7

rotate plane polarised light

Question 8

plane polarised light

Answer 8

• normal light = vibrates in all direction
• if goes though polarised filter = the plane = polarised and light vibrates in same plane

Question 9

Rotation of plane polarised light

Answer 9

polarised light - through optically active mixture - mole andlight react = polarisation of vibration of light
- 2 enantiomers - rotate in oppodireciton - cancel each other ( anti / clockwise

Question 10

Carbonyl group

Answer 10

alde = end
ketone = middle

Question 11

Aldehyde

Answer 11

easily oxidized to COOH
- att to hydrogen to carbonyl group

As aldehyde oxidised - another reduced
- reagent used that changes colour as get reduced

Question 12

Ketone

Answer 12

can’t be easily oxidised
- for the hydrogen to attach - need to break C-C bond

Question 13

Tollens reagent

Answer 13

• colourless solution of silver nitrate dissolved in aq ammonia
• heat in test tube
• alde = silver mirror

Question 14

Fehlings solution

Answer 14

Blue solution of complexed copper (II) ions dissolved in NaOH
- heated
- brick red precipitate of copper oxide

Question 15

Reducing aldehyde and ketone

Answer 15

• using NaBH4 ( sodium borohydride)
• [H] = used as reducing agent

Aldehydes = Produce primary alcohol
Ketone = secondary alcohol

• nucleophilic addition

H+ = from water or weak acid

Question 16

Hydronitriles

Answer 16

Suffix = nitrile
Prefix = hydroxyl

Question 17

Producing hydronitriles

Answer 17

Nucleophilic addition reaction
Need KCN, aldehyde/ketone and dilute acid

KCN = dissociates in water
CN = neg - attackers the carbon cation
Break the C=O bond
O forms bond with H from dilute acid

Question 18

Racemic mixture of hydroxylnitrile

Answer 18

C=O & C=C bonds = planar

Nucleophile can attack either from the top / bottom of the plane = produces different enantiomers
Enantiomers = mirror image of each other , can’t be superimposed - can tell them apart ( most have chiral Center )

Equally likely to form any enantiomers

Question 19

KCN

Answer 19

• toxic
  Reaction need to be done in fume cupboard
• risk of some HCN gas being released form solu

Question 20

Dissociation of COOH

Answer 20

Carboxylate ion and H+
- reaction is reversible but equi lied to the left as much doesn’t dissociate

Question 21

Carboxylic acid and carbonates/ hydrogen carbonates

Answer 21

Salt , CO2 and water

Carbonates ( CO3^ 2- )
Hydrogen carbonates ( HCO3^ - )

Question 22

Esterfication

Answer 22

• heat COOH with alcohol in presence of strong acid
• get ester

Question 23

Naming ester

Answer 23

• alkyl group form alcohol ( first )
• oic acid to oate

C=O : carboxylic acid (count the carbon with double bond O )

Question 24

Useful properties of ester

Answer 24

• Ester have sweet smell = perfume / food flavouring
• ester = polar liquid so lots of polar mole dissolve
• plasticisers = make plastic more flexible

Question 25

Hydrolysis of ester ( acid )

Answer 25

Hydrolysis = splitting of water Acid = catalyst **Reflux**with dilute acid Ester + water = COOH + OH - reversible = put lot of water to push equi to right - get lot of product

Question 26

Base hydrolysis of ester

Answer 26

- reflux ester with dilute alkali - get carboxylate ion and **alcohol** C=OOR + OH- = C=OO- + R-OH

Question 27

Fats and oils

Answer 27

Satu - no double bond ( solid in room temp ) Unsatu - double bond Satu = fit neatly- inc the van der walls force bet them - high temp Unsatu - bent and form kinks

Question 28

Hydrolysis of fat and oils

Answer 28

- hydrolyse by heating them in NaOH ( base hydrolysis) - OH - react with fat / oil Form carboxylate ion (sodium salt ) - soap and alcohol ( glycerol )

Question 29

Soap to COOH

Answer 29

Sodium salt and HCL = COOH Hydrogen subs out the Na+

Question 30

Biodiesel

Answer 30

- oils be converted to biodiesel - methanol + fat ( cata strong alkaline- KOH / NaOH) - produce glycerol and methyl ester (biodisel )

Question 31

Acyl chloride

Answer 31

General formula = CnH2n-1 OCL Func group = COCl -oyl chloride

Question 32

Reaction of Acyl chloride and water

Answer 32

- Cl sub by O2 - react vigorously with cold water - produce = COOH AND HCL

Question 33

Reaction with Acyl chloride with alcohol

Answer 33

- react vigorously at room temp - produce ester and HCL - irreversible reaction = faster way to produce ester than esterfication observation - smoky / misty / white fumes because HCL released

Question 34

Reaction with Acyl chloride and ammonia

Answer 34

- react vigorously - produce amine and HCL

Question 35

Reaction with Acyl chloride and primary amines

Answer 35

- react vigorously - produce N- substituted amide And HCL

Question 36

Acyl chloride and other reaction

Answer 36

-nucleophilic additions - elimination Step 1 = nucleophile adds onto the acyl chloride, displacing the Cl Step 2 = the hydrogen leaves to create an acyl chloride derivative Step one 1. Break C=O, nucleophile attacks the carbon cation 2. Oxygen forms double bond with carbon, release Cl bond ( nucleophile = positive ) Step 2 1. Hydrogen donates it electron to positive nucleophile = release H + ION The left nucleophile and other stuff = acyl chloride derivative 2. H+ ion and Cl- on join together = hydrochloric acid

Question 37

Acid anhydride

Answer 37

- 2 identical COOH acid mole - joined together via oxygen with carbonyl groups on either side Produced water and anhydride

Question 38

Reaction with acid anhydride and water

Answer 38

Produce COOH 2x ethanoic acid

Question 39

Reaction with acid anhydride and alcohol

Answer 39

Ester COOH - ethanoic acid

Question 40

Reaction with acid anhydride and ammonia

Answer 40

- amide - COOH = ehtanoic acid

Question 41

Reaction with acid anhydride with amines

Answer 41

N substituted amide COOH - ethanoic acid

Question 42

Manufacturing of aspirin

Answer 42

- made by reacting salicylic acid with either ehtanoic anhydride or ethanol chloride ethanoic anhydride more use - cheaper - less corrosive - react more slowly with water - don’t predict dangerous hydrogen chloride fumes

Question 43

racemates

Answer 43

- contains equal quantities of each enantiomers of optically active compound - don't show any optical activity - 2 enantiomers cancel each other light rotating effect nucleophile can attack from above or below the place of the bond