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Organic Chemistry Flashcards

1
Q

What do you need for EZ isomerism to occur?

A

C=C double bond to prevent rotation about the double bond

2 different groups of atoms attatched to each C atom either side of the double bond

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2
Q

What is optical isomerism

A

Different type of stereoisomerism
Arises when structures have the same structural / molecular formula but have a different effect on the plane of polarised light

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3
Q

What is an enantiomer

A

Non super impossible mirror images that have the ability to rotate the plane of polarises light either to the left or too the right

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4
Q

What is a race mix?

A

An equimolar mixture of the 2 enantiomers - optically inactive as the rotating effect of one enantiomer cancels out the effect of another

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5
Q

How can enantiomers be separated

A

Resolution

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6
Q

What is a chiral Carbon

A

A tetrahedral C atom which has four different groups of atoms attatched

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7
Q

What is the kekule structure

A

The theoretical vision of benzene. It explained some of its properties but not all - wrong tho - as it was thought to be alternating c-c single / double bonds

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8
Q

What is delocalisation Engery

A

The extra stability exhibited by benzene due to the delocalised pi electrons.

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9
Q

Describe the structure and bonding in benzene

A

Planar with a ring of 6C atoms
Each C atoms forms 3 covalent bonds with 2C atoms and 1H atom
The spare election in the p orbital overlaps sideways to form the pi bond
The is an electron cloud above and below the plane of C atoms
The pi electron are delocalised and benzene is more stable due to this
All c-c bond lengths are equal

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10
Q

What type of reaction does benzene under go and describe it

A

Electrophilic substitution

Pi es are not disrupted, stability is not lost and a lot more energy is not required

Not Electrophilic addition because this would disrupt the pi electrons and stability would be lost. Alkenes do not have delocalised es they have localised double bonds hence addition is more suitable

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11
Q

Describe the conditions needed for nitration

A

C. Nitric acid and C. Sulfuric acid below 55 degrees

NO2+ is the Electrophile

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12
Q

Describe the conditions needed for halogenation if benzene

A

AlCl3 / AlBr3 - Cl/Br not strong enough - RT/ No light. Anhydrous

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13
Q

Describe friedal crafts reactions

A

AlCl3 / anhydrous / RT

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14
Q

What are the catalysts used for

A

Polarise the halogen

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15
Q

Give the reaction for the formation of alcohols from halogenoalkanes

A

1 atm
Reflux
NAOH

RX + NAOH –> ROH + NaX

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16
Q

Alcohol and HYDROGEN CYANIDE

A

Zncl2 catalyst / anhydrous

ROH + HCL –> RCL + H20

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17
Q

Alcohols and HYDROGEN BROMIDE

A

KBr / H2SO4 = HBr

HBr + ROH –> RBr

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18
Q

Describe oxidation reactions

A

Primary alcohol –> c.acid

Aldehyde –> c. Acid

Primary alcohol –> aldehyde

Secondary alcohol –> ketone

Acidified sodium dichromate (vi) and aqueous sulfuric acid and REFLUX for c.acid / distill off for aldehyde

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19
Q

What is the colour change in an oxidation reaction

A

Orange to green

Ketones are not easily oxidised so no colour change is seen

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20
Q

Describe reduction reactions

A

C. Acid -primary alcohol
Aldehyde –> primary alcohol
Ketone - secondary alcohol

Reducing agents
Works for all - LiAlH4 anhydrous RT
Only aldehydes and ketones NaBH4 (aq) RT

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21
Q

Reaction - alcohol and carboxylic acid

A

Reflux conc h2so4

ESTER formed - RCOOR

Ester is separated by distillation

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22
Q

Describe how acid chlorides are formed

A

Alcohol + acid chloride –> ester

No H bonding
Basic catalyst used to neutralise acidic HCL formed
Anhydrous

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23
Q

Why is phenol described as an extended pi system

A

The Spare electron in the P orbital of the O atom overlaps with the delocalised electron to form an extended pi system

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24
Q

Chlorobenzene Vs 1-chlorobutane

A

Test - Heat with NAOH and add acidified nitric acid and silver nitrate

Halogenoalkane undergoes nucleophillic substitution and produces a white ppt

Chlorobenzene more resistant to hydrolysis because of extended pi system

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25
Q

Describe the trend in acidity between ethanol, water, phenol and ethanoic acid

A

Ethanol - the ph is 7.3 - alkyl groups are electron donating - no delocalised - charge so not stable so not likely to give up H+

Water is only slightly more likely to give up H+ that ethanol

Phenol - the - charge is delocalised onto the ring because the spare e- in the p orbital of the O atom overlaps sideways to form an extended pi system

Ethanoic acid - the - charge is delocalised above the O atom so it is very likely to give up H+

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26
Q

Describe the reaction between phenol and bromine

A

A tri substituted product is formed

C6H5OH + 3BR –> C6H2Br3OH

ELECTROPHILLIC SUBSTITUTION
A catalyst is not required
Conc bromine not required
Mono sub pro duct not produced

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27
Q

What is the product of phenol and ethanoyl chloride

A

ESTER

Phenyl ethanoate

Draw out

C6H5OH + CH3COCL –> C5H6OOCCH3 * HCL

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28
Q

Describe the chemical tests for alcohols

A

FECl3 - only works on aromatic OH groups - NOT ethanol m
• purple colour if positive

Iodoform - I2 / NaOH(aq) 
•CH3CHOH
Ethanol on primary alcohol 
Tertiary alcohols don't 
Propan-2-ol does

YELLOW ppt and antiseptic smell

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29
Q

What is the mechanism for HCN

A

Draw mechanism

Reaction is nucleophilic addition because the CN ion acts as a nucleophile attacking the C of the carbonyl Carbon

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30
Q

Describe the tests for an aldehyde / ketone

A

Tollens test - aldehyde only
Silver mirror forms
Heat with AgNO3 - the Ag+ is reduced to AG(s)
Ag + e –> Ag(s)

Fehlings - Aldehyde only
Colour change blue –> red
Because copper 2 sulphate containing Cu2+ is reduced to Copper oxide (Cu+)

2,4-DNP - Works for both
Produces organge / yellow crystals for a positive result -
NUCLEOPHILLIC ADDITION ELIMINATION
Add the Unknown to 24DNP in dilute methanol/ acid. Orange crystals with form. Wash with cold water and filter. Dry then take MPT and compare with literature value

IODOFORM - I2/ NAOH
Yellow ppt and an antiseptic smell - CH3CO = positive result
Ethanal is only aldehyde to do this

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31
Q

How do you convert C. Acids to Acid Chlorides ?

A

Nucleophillic substitution

Can use PCL5 or SOCL2

PCl5
PCl5 + CH3COOH –> PCLO3 + CH3COCL + HCL

SOCL2 + CH3COOH –> SO2 + HCL + CH3COCL

SOCl2 is preferred as only gaseous coproducts are produced

The conditions must be ANHYDROUS or the acid chlordide will hydrolyse the acid

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32
Q

Hydrolysis of acid chlorides

A

RCOCL + H2O –> RCOOH + HCL

Nucleophillic substitution

Open a bottle of ethanoyl chloride = misty fumes of hydrogen chloride are seen

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33
Q

Hydrolysis of esters ? ACID

A

Heat with HCL (aq)

RCOOR + H2O –> RCOOH + ROH

Eg ethyl propanoate will give ethanol and propanoic acid

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34
Q

Alkaline hydrolysis of Esters ?

A

2 steps

1) Heat with NAOH(aq)

RCOOR + NAOH –> RCOO-Na+ + ROH

Acidity the sodium salt with HCL

2) RCOO-Na+ + HCL –> RCOOH + NaCl

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35
Q

Describe the solubility of sodium salts and c.acids

A

Sodium salts are fairly soluble in water

Aliphatic acids are fairly soluble in water such as ethanol

Aromatic acids are sparingly soluble in water

so therefore if the sodium salt of benzoic acid is treated with HCL the carboxylic acid will ppt out of the solution

To get product you 
•filter 
•wash with cold water 
•recrystallise with hot water 
•dry in over below the mpt
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36
Q

How to form a aromatic C.acid

A

Reagent = aqueous alkaline potassium manganate (V11)

Product is a sodium salt -
Salt acidified with HCL to produce the aromatic acid

37
Q

How do you produce an acidic proton ?

A

An acidic proton will react with NAOH

Eg in phenol in C.acid
NOT in ethanol

38
Q

Describe decarboxylation

A

React with C.acid with NAOH for form a sodium salt.

Heat the sodium salt with sodalime NAOH

A hydrocarbon chain with one less C atom will form - eg is ethanoic acid is parent c acid then the product will be methane

CH3COOH + NAOH –> CH3COO-Na+ +H2O

CH3COO-Na+ + NAOH –> CH4 + Na2CO3

39
Q

Test for CO2?

A

Turns lime water milky when you bubble CO2 through it

Carboxylic acids liberate CO2 from NaHCO3

40
Q

What is nitrous acid and what type of reaction does it undergo

A

NaNO2 + HCL

Nucleophillic substitution

41
Q

Aliphatic amine + HNO2 ANY TEMP

A

Alcohol + N2 gas formed (and H2O)

Eg CH3CH2NH2 + HNO2 – CH3CH2OH + N2 + H2O

42
Q

Aromatic amine + HNO2 ROOM TEMP

A

Phenol formed … + N2 GAS

C6H5NH2 + HNO2 –> C6H5OH + N2 + H2O

43
Q

Aromatic amine - COLD (> 10)

A

Benzene diazinon chloride is produced

C6H5NH2 + NaNO2 + 2HCl –> C6H5N2+Cl- +NaCl + 2H2O

Excess HNO2 must be used as any un used phenyl amine can couple with benzenediazonoum chloride - yellow dye !!

44
Q

What if the cold benzene diazoniumchloride is allowed to warm to room temp in the presence of water

A

Phenol will form with N2 gas bubbles

C6H5N2+Cl- + H20 -> C6H5OH +N2 + HCl

BDC has decomposed

45
Q

What is benzenediazonoum chloride

A

Useful intermediate in the synthesis of organic compounds called Azo dyes.

46
Q

How are Azo dyes produced?

A

Produced during a coupling reaction - the linking of two benzene rings together. To form a single, large molecules under alkaline conditions using NAOH -

47
Q

What does the colour depend on when using Azo dyes

A

What aromatic compound is coupled to BDC -

48
Q

Dyes are..?

A

All the dyes are filtered and purified and have Ph 13/14

49
Q

BDC + NAOH + PHENOL

A

Orange dye-

4-phenylazophenol + NaCl + H2O

C6H5OH + C5H5N2+Cl- + NAOH –> C6H5N2C6H4OH + NaCl + H2O

50
Q

BDC + NAOH + PHENYLAMINE

A

yellow dye
4-phenylazophenylamine

C6H5NH2 + C6H5N2+Cl- +NaOH –> C6H5N2C6H4NH2 + NaCl + H2O

51
Q

BDC + NAOH + NAPHTHALEN-2-OL

A

red dye
1-phenylazonaphthalene-2-ol

C10H7OH + C6H5N2+Cl- + NAOH –> C6H5N2C10H6OH + NaCl + H20

52
Q

How are the colours produced ?

A

The colours arise from the overlap of the pi electrons form the N=N bond and the delocalised pi electrons of the 2 benzene rings - conjugate system - the systems absorb electromagnetic radiation in the visible part of the electromagnetic spectrum and are known as CHROMOPHORES

53
Q

Chemical test amine?

A

1- Add HNO2 acid to both in cold conditions. bubbles of N2 gas are seen with the aliphatic amine, no bubbles are seen with the aromatic amine

2- Add HNO2 to both in cold alkaline conditions and add an aromatic compound such as phenol - a colour ppt is produced with the aromatic amine and no colour is produced with the aliphatic amine

54
Q

Converting C.Acids to amides

A

C . Acid –> acid chloride

PCL5/SOCL2

Acid chloride –> amide
Conc / dry NH3

CH3COCL + NH3–> CH3CONH2 + HCL

55
Q

Dehydrating ammonium salt

A

Acid + carbonate –> salt

RCOOH + (NH4)2CO3 –> RCOO-NH4+ + CO2 + H2O

RCOO-NH4+ —-> RCONH2 + H2O
salt dehydrates

56
Q

Amide from ester?

A

Ester reacts with ammonia

RCOOR + NH3 –> RCONH2 + ROH

57
Q

ACID hydrolysis of amide

A

RCONH2 –> RCOOH + NH4Cl

•HCL / REFLUX /H20

58
Q

ALKALINE hydrolysis

A

RCONH2 —> RCOO-Na+ + NH3
•NAOH / REFLUX

RCOO-Na+ –> RCOOH + NaCl
•HCL

59
Q

Reduction of primary amides

A

LiAlH4
DRY
AMINE FORMED

eg ethanamide will form ethylamine

60
Q

Nylon 6,6?

A

Hexane-1,6-dicarboxylicacid + 1,6-diaminohexane = nylon 6,6

Draw
Make sure no HO / H on the ends of the repeating unit . N at bottom of bracket. + H2O is apparent

The link is called the amide link
1,6-diaminohexane is produced from the reduction of the nitrile using LiAlH4

61
Q

Nylon-6?

A

Single monomer called caprolactam
•250 degrees / 10% water
This causes the ring to open and polymerisation to occur

62
Q

Kevlar ?

A

Benzene1,4-dicarboxylicacid + 1,4-diaminobenzene

Condesation polymer

63
Q

Condensation Vs addition polymer

A

Condesation
•atom economy less than 100%
•one large polymer formed and a small molecule is lost
•2 functional groups needed in the monomers

Addition
•atom economy is 100%
•one large molecule is formed but none are lost
• only 1 functional group is needed C=C

64
Q

Polyester PET (terylene)

A

1,4-benzenedicarboxylic acid + ethane,1-2-diol

also called esterification
Textile industry - spun with cotton to form polychrome fibres

65
Q

Describe the basic strength of phenyl amine

A

Electron density of the nitrogen lone pair is increased due to the inductive effect of the aromatic ring. The ring is electron withdrawing meaning the nitrogen atom accepts a H+ less readily

66
Q

Describe the basic strength of ethylamine

A

Electron density is of the nitrogen lone pair is increased due to the inductive effect of the alkyl group’ alkyl groups are electron donating meaning the nitrogen atom accepts a H* more readily

67
Q

Basic nature of amines

A

All amines are basic because the nitrogen atom has a lone pair of electrons which can accept protons. (Protons have no electrons in the valence she’ll so lone pair is used to form coordinate bond)

68
Q

How to test for a base

A

Bases turn red litmus paper blue / turns universal indicator blue

69
Q

Preparation of primary amine

A

FROM HALOGENOALKANE
Halogenoalkane heated with excess ammonia dissolved in ethanal carried out in a sealed tube immersed in boiling water
Nucleophillic substitution

Ch3Ch2Cl + NH3 -> Ch3Ch2NH2 + HCL

70
Q

How does the basic nature of amines affect this

A

As the amine is basic, a soluble amine salt is formed as the amine accepts H+

Ch3Ch2NH2 + HCL –> Ch3Ch2NH3+Cl-

TREAT WITH NAOH to get AMINE

Ch3Ch2NH3+Cl- + NAOH –> CH3CH2NH2 + NACL + H2O

71
Q

How do u prepare phenyl amine from nitrobenzene

A

Nitrobenzene is reduced with tin and conc HCL. The mixture is the heated and a soluble salt is formed. NAOH is then added to form phenyl amine. Steam distillation used to separate

72
Q

Amine + ethanoyl chloride

A

Nucleophillic substitution

N substituted product is formed

Ch3COCl + CH3NH2 -> CH3CONHCH3 +HCL
N-methylethanamide

73
Q

What is different about nitriles

A

Adding an extra C atom onto the chain

74
Q

How to form a nitrile???

A

FROM HALOGENOALKANE

Reflux KCN in solution of ethanol to form the nitrile

• extra C atom added

Ch3Ch2Cl + KCN –> Ch3Ch2CN
Chloroethane –> propane nitrile

75
Q

Reduction of nitriles ?

A

LiAlH4 used
Hydrogen added
Primary AMINE is formed

C atoms stay the same !!!

Ch3Ch2CN —> Ch3Ch2Ch2Nh2

76
Q

How do you produce butyl amine from 1-chloropropane

A

Halogenoalkane –> nitrile
• ADDS A C ATOM

Ch3Ch2Ch2Cl + KCN -> CH3CH2CH2CN +KBr
•reflux KCN in ethanol

Nitrile –> Amine
•REDUCTION OF NITRILE USING LIALH4

Ch3Ch2Ch2CN —–> Ch3Ch2Ch2Ch2NH2

77
Q

Acid hydrolysis of nitriles

A

Reflux with HCL

Carboxylic acid and ammonium salt formed

78
Q

Alkaline hydrolysis of nitriles

A

Add H2O + NAOH to form the sodium salt and ammonia

Add HCL to sodium salt and a carboxylic acid is formed

79
Q

C.Acid —> Nitrile

A

Acid –> ammonium salt
•acid + carbonate = salt

Ammonium salt — amide
• dehydrates

Amide —> nitrile
•Phosphorus V oxide (P4H10)
Nitrile + H20 forms

80
Q

Name of glycine

A

2-aminoethanoic acid

81
Q

Name of alanine

A

2-aminopropanoicacid

82
Q

Name of serine

A

2-amino-3-hydroxypropanoic acid

83
Q

Describe the primary structure of protein

A

The precise sequence of amino acids

84
Q

secondary protein structure

A

Forms an alpha helix- held in place by h bonds between peptide links. Results from hb which occur between Nh/Co of polypeptide

85
Q

Describe the amphoteric / zwitterionic nature of amino acids

A

Amino acids contain both basic amino and acid group
Predominately exist as internal salts called zwitterions

In acidic conditions acts as a base
In alkaline conditions acts as a acid

86
Q

Describe the
•mpt of amino acids
•solubility

A

Amino acids have high mpt due to the strong ionic binding present and a lot of energy is needed to overcome the bonding and melt them

Soluble as the exhibit ionic properties

87
Q

Amino acids and ethanoyl chloride

A

Fume cupboard - HCL produced
Dry / anhydrous
Ending ethanamide if CH3COCl

88
Q

Describe abit about amines

A

H bonding between molecules

H bonding weaker than alcohols N is les ENG than O (Bp also )

History (3 decks)

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