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mechanisms Flashcards

1
Q

free radicals: going from and to

A

alkane to haloalkane

haloalkane to di haloalkane

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2
Q

Describe the three steps of free radical substitution

A

initiation-What a chlorine radical is formed from chlorine [Cl2] this requires UV light
propagation-What a single chlorate radical reacts
termination-where two radicals combine together forming either a major or minor product

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3
Q

What are the conditions for free radical substitution

A

UV light

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4
Q

Give an example of a free radical substitution with methane and chlorine going through all the steps

A

CH4 + Cl2
initiation: Cl2 -> 2Cl.
propagation: CH4 + .Cl -> .CH3 + HCl
.CH3 + Cl2 ->CH3Cl + .Cl
termination: major: .CH3 + .Cl -> CH3Cl
minor: .CH3 + .CH3 -> 2CH3

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5
Q

How do you double check that the major product is correct

A

The major product should also appear in the second propagation step

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6
Q

Nucleophilic substitution: going from and to

A

haloalkane to alcohol/nitrile/amine

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7
Q

What are the conditions for a Haloalkane reacting with a alcohol nuclophile

A

Warm and aqueous

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8
Q

What are the conditions for a halo alkane reacting with a cyanide nucleophile [nucleophilic substitution]

A

Aqueous and dissolved in ethanol. heat it with

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9
Q

What are the conditions for a haloalkane reacting with a ammonia nucleophile [nucleophilic substitution]

A

dissolved in ethanol
ammonia in excess
hit it on the reflux in a sealed tube in high-pressure

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10
Q

What is the definition of a nuclophile

A

they are an electron pair/lone pair donor

They are attracted to a Delta positive species

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11
Q

What do the arrows go from and to nucleophilic substitution [hydroxide and cyanide nuclophile’s only]

A

First arrow: from the middle of the lone pair on the nucleophile to the Delta positive carbon with the halogen attached

Second Arrow: from the middle of the carbon halogen bond onto the halogen [breaking the halogen off]

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12
Q

Where do the arrows go from and to in nucleophilic substitution [ammonia nucleophile only] requires an intermediate and a second ammonia molecule

A

first arrow: from the middle of the lone pair of the ammonia nucleophile to the delta positive carbon with halogen attached

Second arrow: from the middle of the carbon halogen bond onto the halogen, breaking halogen off

intermediate

Third arrow: from the middle of the lone pair of the second ammonia nucleophile to a hydrogen with a nitrogen group attached. Nitrogen must have a positive charge

Fourth arrow: from the middle of the hydrogen nitrogen bond, onto the nitrogen.

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13
Q

Bass elimination: going from and to

A

Halo alkane to alkene

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14
Q

What are the conditions that favor elimination from nucleophilic substitution

A

using a high temperature and using ethanol as a solvent

Also using anhydrous conditions [absence of water/H2O]

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15
Q

Where do the arrows go from and to in base elimination

A

reacting chloroethane with a hydroxide nucleophile

First arrow: from the middle of the lone pair on the nucleophile to a hydrogen which is joined to a carbon which is adjacent to the carbon with the halogen.

Second arrow: From the CH bond to the CC bond

Third arrow: from the middle of the carbon halogen bond onto the halogen breaking the halogen off.

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16
Q

What are the products of base elimination

A

water/H2O

kCl/NaCl [any other halogen]

alkene

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17
Q

What type of isomers can be formed from base elimination

A

Geometric isomers

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18
Q

Which nuclophile does not have a negative charge

A

Ammonia

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19
Q

Electrophilic addition: going from and to

A

Alkene to alkane [sometimes halo alkane]

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20
Q

What is the significance of the name electrophilic addition

A

That you are eliminating the double bond in the alkene due to addition

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21
Q

What happens when an alkene reacts with a halogen e.g. bromine [Br2] Electrophilic addition

A

An induced dipole force between two bromine molecules allowing one to have a slightly Delta positive charge and one to have a slightly Delta negative charge

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22
Q

What happens when a alkene reacts with a hydrogen halide [electrophilic addition]

A

The hydrogen will have a slightly Delta positive charge whilst a halogen will have a slightly Delta negative charge

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23
Q

Why does a secondary/tertiary Carbo cation formed over a primary Carbo cation. Electrophilic addition

A

Because a secondary/tertiary carbocation is more stable than a primary carbocation due to a positive inductive effect.

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24
Q

What happens when an alkene reacts with sulfuric acid [electrophilic addition] name the type of product formed

A

Methyl/Ethel/propyl/butyl….. hydrogen sulphate

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25
Q

Draw the structure of sulfuric acid

A 
O      O
   “   “
     S
     /\
   O  O
    |  |
   H  H
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26
Q

Describe where the arrows go in electrophilic addition

A

first arrow: From the middle of the carbon carbon bond to the slightly delta positive region on the reactant

Second arrow: from the middle of the hydrogen halide/bromine/OH bond onto the slightly delta negative atom

third arrow: After the Carbocation has formed the nucleophile formed from the slightly delta negative element/atom reacts. The arrow goes from the middle of the lone pair into the positive carbocation carbon

This forms a halo alkane in most cases

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27
Q

Where does the arrow go from and to when an alkene reacts with sulfuric acid in electrophilic addition

A

The hydrogen from one hydroxyl group is slightly positive was the oxygen is slightly negative. The same process occurs breaking off the hydrogen. The oxygen now has a lone pair and a negative charge so that reacts with the Carbocation Forming something hydrogen sulphate

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28
Q

Describe hydration of an alkene with H2O/water. This falls under electrophilic addition

A

The alkene reacts with water to form an alcohol with no further products

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29
Q

What are the conditions for the hydration mechanism [electrophilic addition]

A

300°C
phosphoric acid catalyst ( H3PO4)
(represented as H+ above the equation arrow)
65 ATM/ Atmospheric pressure

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30
Q

Elimination from alcohols: going from And to

A

From an alcohol to an alkene

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31
Q

What type of catalyst is needed in the mechanism elimination from alcohols

A

H+

Concentrated sulphuric acid

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32
Q

What are the conditions needed for elimination from alcohols

A

concentrated H2 SO4 (sulphuric acid)
heat



33
Q

What are the products of elimination from alcohols

A

alkene
water/H2O
H+ catalyst (Regenerated)

34
Q

Where do the arrows go from And to an elimination from alcohols

A

First arrow: there is a lone pair on the oxygen from the hydroxyl group. The arrow goes from the middle of the lone pair to the H+ catalyst

Second arrow: the oxygen is now bonded to 2 hydrogen is giving it a positive charge. The arrow goes from the middle of the CH bond to the middle of the CC bond. 

third arrow: in the middle of the carbon oxygen bond onto the oxygen.

This breaks of the water molecule leaving a double bond between the two carbons


35
Q

What type of isomers can be formed from elimination from alcohols mechanism

A

Geometric isomers (trans-and cis)

36
Q

Nucleophilic addition: going from and to

A

going from a carbonyl compound (C=O) to an alcohol. with NaBH4

going from a carbonyl compound to a hydroxy nitrile with KCN/HCN

37
Q

What type of mechanisms can nucleophilic addition be classed as

A

Reduction mechanisms

38
Q

why is KCN more favourable than HCN as a reactant

A

because HCN is very toxic and poisonous

39
Q

what are the conditions needed in nucleophilic addition with NaBH4

A

NaBH4 is aqueous/ dissolved in water

40
Q

What type of nucleophiles can be used in nucleophilic addition

A

:CN- or :H-

41
Q

Where did the arrows go from and to in nucleophilic addition with sodium tetrahydroborate (NaBH4)

A

first arrow: from the middle of a lone pair on the H- nuclophile To the Delta positive carbon with the oxygen attached.

Second arrow: from the middle of the double carbon oxygen bond onto the oxygen

Third arrow: this leaves oxygen with a lone pair and a negative charge. From the Middle of the lone pair onto the H plus catalyst.

42
Q

What is the product of nucleophilic addition with sodium tetra Hydro borate (NaBH4)

A

A primary or secondary alcohol depending on it being an aldehyde or ketone

43
Q

Where do the arrows go from and to nucleophilic addition with potassium cyanide (KCN)

A

first arrow: from the middle of the lone pair of the cyanide nucleophile To the Delta positive carbon with the oxygen attached

Second arrow: from the middle of a carbon oxygen bond onto the oxygen

Third arrow: this leaves the oxygen with a lone pair and a negative charge. The arrow goes from the middle of the lone pair to the hydrogen/H+ catalyst.

44
Q

how do you name the product formed from nucleophilic addition with potassium cyanide (KCN)

A

You states where the hydroxyl group is and any other Carbon groups

Carbon 1 is always labeled is the carbon from the cyanide group

eg. 2-hydroxy, 2-methyl butane nitrile 

45
Q

What two species are reactants in nucleophilic addition elimination

A

acyl chlorides

acid Anhydrides

46
Q

which from acid anhydride or acyl chlorides do you have to remember drawing a mechanism for

A

acyl chlorides

47
Q

What are the four different reactants that can react in nucleophilic addition elimination

A

water/H2O
alcohols
ammonia
Amines

48
Q

how do you name the product formed in nucleophilic addition elimination when an acyl chloride reacts with an amine

A

N-methyl ethanamide 

49
Q

Where do the arrows go from and to nucleophilic addition elimination with an acyl chloride

A

first arrow: from the lone pair on either the oxygen or the nitrogen depending on the reactant onto the delta positive carbon

Second arrow: from the middle of the carbon oxygen double bond onto the oxygen.

This leaves, the double bond broken and leaves the oxygen with a lone pair and a negative charge.
The oxygen or nitrogen has a positive charge. And the carbon forms 4 bonds.

third arrow: from the middle of the lone pair on the oxygen onto the middle of the carbon oxygen bond

Fourth arrow: from the middle of the carbon chloride bond onto the chloride (Breaking the chloride off)

Fifth arrow: from the nitrogen hydrogen bond/oxygen hydrogen bond onto the nitrogen or oxygen.

50
Q

What are the products formed in almost every nucleophilic addition elimination reaction with acyl chlorides

A

HCl

but with ammonia NH4Cl forms instead 

51
Q

Write out the reaction for ethanoic anhydride reacting with water (nucleophilic addition elimination)

A

(CH3CO)2O + H2O -> 2(CH3COOH)

Products are two carboxylic acids

52
Q

Write out the reaction for ethanoic anhydride reacting with methanol (Nucleophilic addition elimination)

A

(CH3CO)2O + CH3OH -> CH3COOH + CH3COOCH3

Products formed are a carboxylic acid and an ester

53
Q

Write out the reaction for ethanoic anhydride ammonia (nucleophilic addition elimination)

A

(CH3CO)2O + 2NH3 -> CH3COOH-NH4+ + CH3CONH2

The products formed are a salt and an amine

54
Q

Write out the reaction for ethanoic anhydride and methyl amine (nucleophilic addition elimination)

A

(CH3CO)2O + CH3NH2 -> CH3COO-NH3+ + CH3CONHCH3

55
Q

what’s a method for remembering how many hydrogen form on each product with NH3/…NH2

A

the product with COO- always gains a hydrogen from the reactant whereas the other product always loses a hydrogen from the reactants amount

eg. 2NH3 -> COO-NH4+ and …CONH2
eg. 2…NH2 -> COO-NH3+ and …CONH…

56
Q

What type of catalyst is used in friedel crafts acylation

A

AlCl3 catalyst

57
Q

what type of product is formed in friedel crafts acylation

A

aryl ketone

58
Q

what’s the actual mechanism name for friedel crafts acylation

A

Electrophilic substitution

59
Q

write out the equation for an acyl chloride reacting with AlCl3 to form an electrophile ( electrophilic substitution) friedel crafts acylation 

A

CH3COCl + AlCl3 -> AlCl4- + CH3-C(+)=O

60
Q

write out the formation of an electrophile when an acid anhydride reacts with AlCl3 (Electrophilic substitution) friedel crafts acylation 

A

(CH3CO)2O + AlCl3 -> CH3-C(+)=O + CH3COOAlCl3-

61
Q

what is the definition of an electrophile

A

lone pair acceptor

Attracted to electron rich areas

62
Q

friedel crafts acylation (Electrophilic substitution): going from and to

A

benzene ring to aryl ketone

63
Q

Where do the arrows go from and to in electrophilic substitution (friedel crafts acylation)

A

first arrow: from the benzene ring to the delta positive carbon on the electrophile

Second arrow: from the middle of the CH bond to the positive inside the benzene ring

64
Q

What are the two mechanisms for electrophilic substitution

A

nitration

friedel crafts acylation

65
Q

What are the conditions for nitration (electrophilic substitution)

A

55°C to prevent further substitution
nitric acid concentrated (HNO3)
concentrated sulphuric acid (H2 SO4)

66
Q

write out the equation for the formation of an electrophile For nitration (electrophilic substitution)

A

H2SO4 + HNO3 -> N(+)O2 + HSO4(-) + H2O

67
Q

Nitration (electrophilic substitution): going from and to

A

from benzene to nitrobenzene

68
Q

What are the products of nitration

A

Nitrobenzene and sulphuric acid

69
Q

Where did the arrows go from and to in nitration/electrophilic substitution

A

first arrow: from the benzene ring to the nitrogen (positive) on NO2 (electrophile)

Second arrow: from the HSO4- to the H from the CH bond

Third arrow: from the middle of the CH bond to the plus in the middle of the benzene ring

70
Q

what are the conditions for the reduction of nitrobenzene to phenyl amime

A

concentrated hydrochloric acid (HCl)
tin / Sn
heat under reflux

Finally: cool with excess sodium hydroxide (NaOH)

71
Q

Write out the equation for reduction of nitrobenzene to phenyl amine

A

nitrobenzene (ring with NO2) + 6[H] -> phenyl amine (ring with NH2) + 2H2O

72
Q

hydration mechanism steps with propene

A

H+ from concentrated H3PO4

step1: from the double bond to the H+
step2: water molecule with a lone pair on the oxygen. from the middle of the lone pair to to carbocation
step 3: oxygen has a + charge. from the middle of the O-H bond onto the O. H+ catalyst regenerated.

73
Q

what are the conditions for acyl chloride mechanisms

A

room temperature

74
Q

what is the condition for acid anhydrides with H2O

A

warm

75
Q

what is the condition for acid anhydrides with ammonia

A

heated under reflux

76
Q

what is the condition for acid anhydrides with an alcohol

A

heated under reflux

77
Q

what is the condition for acid anhydrides reacting with an amine

A

heated under reflux

78
Q

what is the mechanism for reduction of alcohols

A

acid elimination / elimination

79
Q

What are the conditions for hydrogenation of an alkene. Electrophilic addition

A

going from an alkene to an alkane

150°C
nickel catalyst Ni

mechanisms personal (1 decks)

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