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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
Draw the structure of sulfuric acid
``` O O “ “ S /\ O O | | H H ```
26
Describe where the arrows go in electrophilic addition
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
27
Where does the arrow go from and to when an alkene reacts with sulfuric acid in electrophilic addition
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
28
Describe hydration of an alkene with H2O/water. This falls under electrophilic addition
The alkene reacts with water to form an alcohol with no further products
29
What are the conditions for the hydration mechanism [electrophilic addition]
300°C phosphoric acid catalyst ( H3PO4) (represented as H+ above the equation arrow) 65 ATM/ Atmospheric pressure
30
Elimination from alcohols: going from And to
From an alcohol to an alkene
31
What type of catalyst is needed in the mechanism elimination from alcohols
H+ Concentrated sulphuric acid
32
What are the conditions needed for elimination from alcohols
concentrated H2 SO4 (sulphuric acid) heat 
33
What are the products of elimination from alcohols
alkene water/H2O H+ catalyst (Regenerated)
34
Where do the arrows go from And to an elimination from alcohols
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
What type of isomers can be formed from elimination from alcohols mechanism
Geometric isomers (trans-and cis)
36
Nucleophilic addition: going from and to
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
What type of mechanisms can nucleophilic addition be classed as
Reduction mechanisms
38
why is KCN more favourable than HCN as a reactant
because HCN is very toxic and poisonous
39
what are the conditions needed in nucleophilic addition with NaBH4
NaBH4 is aqueous/ dissolved in water
40
What type of nucleophiles can be used in nucleophilic addition
:CN- or :H-
41
Where did the arrows go from and to in nucleophilic addition with sodium tetrahydroborate (NaBH4)
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
What is the product of nucleophilic addition with sodium tetra Hydro borate (NaBH4)
A primary or secondary alcohol depending on it being an aldehyde or ketone
43
Where do the arrows go from and to nucleophilic addition with potassium cyanide (KCN)
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
how do you name the product formed from nucleophilic addition with potassium cyanide (KCN)
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
What two species are reactants in nucleophilic addition elimination
acyl chlorides | acid Anhydrides
46
which from acid anhydride or acyl chlorides do you have to remember drawing a mechanism for
acyl chlorides
47
What are the four different reactants that can react in nucleophilic addition elimination
water/H2O alcohols ammonia Amines
48
how do you name the product formed in nucleophilic addition elimination when an acyl chloride reacts with an amine
N-methyl ethanamide 
49
Where do the arrows go from and to nucleophilic addition elimination with an acyl chloride
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
What are the products formed in almost every nucleophilic addition elimination reaction with acyl chlorides
HCl but with ammonia NH4Cl forms instead 
51
Write out the reaction for ethanoic anhydride reacting with water (nucleophilic addition elimination)
(CH3CO)2O + H2O -> 2(CH3COOH) | Products are two carboxylic acids
52
Write out the reaction for ethanoic anhydride reacting with methanol (Nucleophilic addition elimination)
(CH3CO)2O + CH3OH -> CH3COOH + CH3COOCH3 | Products formed are a carboxylic acid and an ester
53
Write out the reaction for ethanoic anhydride ammonia (nucleophilic addition elimination)
(CH3CO)2O + 2NH3 -> CH3COOH-NH4+ + CH3CONH2 The products formed are a salt and an amine
54
Write out the reaction for ethanoic anhydride and methyl amine (nucleophilic addition elimination)
(CH3CO)2O + CH3NH2 -> CH3COO-NH3+ + CH3CONHCH3
55
what’s a method for remembering how many hydrogen form on each product with NH3/…NH2
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
What type of catalyst is used in friedel crafts acylation
AlCl3 catalyst
57
what type of product is formed in friedel crafts acylation
aryl ketone
58
what’s the actual mechanism name for friedel crafts acylation
Electrophilic substitution
59
write out the equation for an acyl chloride reacting with AlCl3 to form an electrophile ( electrophilic substitution) friedel crafts acylation 
CH3COCl + AlCl3 -> AlCl4- + CH3-C(+)=O
60
write out the formation of an electrophile when an acid anhydride reacts with AlCl3 (Electrophilic substitution) friedel crafts acylation 
(CH3CO)2O + AlCl3 -> CH3-C(+)=O + CH3COOAlCl3-
61
what is the definition of an electrophile
lone pair acceptor | Attracted to electron rich areas
62
friedel crafts acylation (Electrophilic substitution): going from and to
benzene ring to aryl ketone
63
Where do the arrows go from and to in electrophilic substitution (friedel crafts acylation)
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
What are the two mechanisms for electrophilic substitution
nitration | friedel crafts acylation
65
What are the conditions for nitration (electrophilic substitution)
55°C to prevent further substitution nitric acid concentrated (HNO3) concentrated sulphuric acid (H2 SO4)
66
write out the equation for the formation of an electrophile For nitration (electrophilic substitution)
H2SO4 + HNO3 -> N(+)O2 + HSO4(-) + H2O
67
Nitration (electrophilic substitution): going from and to
from benzene to nitrobenzene
68
What are the products of nitration
Nitrobenzene and sulphuric acid
69
Where did the arrows go from and to in nitration/electrophilic substitution
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
what are the conditions for the reduction of nitrobenzene to phenyl amime
concentrated hydrochloric acid (HCl) tin / Sn heat under reflux Finally: cool with excess sodium hydroxide (NaOH)
71
Write out the equation for reduction of nitrobenzene to phenyl amine
nitrobenzene (ring with NO2) + 6[H] -> phenyl amine (ring with NH2) + 2H2O
72
hydration mechanism steps with propene
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
what are the conditions for acyl chloride mechanisms
room temperature
74
what is the condition for acid anhydrides with H2O
warm
75
what is the condition for acid anhydrides with ammonia
heated under reflux
76
what is the condition for acid anhydrides with an alcohol
heated under reflux
77
what is the condition for acid anhydrides reacting with an amine
heated under reflux
78
what is the mechanism for reduction of alcohols
acid elimination / elimination
79
What are the conditions for hydrogenation of an alkene. Electrophilic addition
going from an alkene to an alkane 150°C nickel catalyst Ni

mechanisms personal (1 decks)

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