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AQA chemistry (13, Halogenoalkanes) > Nucleophilic substitution in halogenoalkanes > Flashcards

Nucleophilic substitution in halogenoalkanes Flashcards

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1
Q

What do nucleophiles attack and form bonds with?

A

positively or partially positively charged carbon atoms

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2
Q

What is a nucleophile?

A

A lone electron pair donor

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3
Q

What things tend to be a nucleophile?`

A

A negatively charged ion or a an atom with a delta negative charge.

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4
Q

How does the nucleophile create a bond with carbon?

A

Carbon atoms are electron deficient and so the nucleophile donates a pair of electrons and swaps places with the halogen in order to create a covalent bond.

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5
Q

What are the names of the three common nucleophiles?

A
  • Hydroxide ion
  • Ammonia
  • Cyanide ion
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6
Q

What is the formula for the hydroxide ion?

A

-:OH

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7
Q

What is the formula for ammonia?

A

:NH3

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8
Q

What is the formula for the cyanide ion?

A

-:CN

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9
Q

How would you represent a halogen?

A

X

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10
Q

How would you represent any negatively charged nucleophile?

A

:Nu-

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11
Q

Draw the general equation for nucleophilic substitution

A

Check pg 208

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12
Q

Draw a curly arrow representing the movement of a pair of electrons

A
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13
Q

Draw a curly arrow representing the movement of a single electron

A
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14
Q

Draw the general mechanism for nucleophilic substitution, along with the curly arrows and partial charges

A

check pg 208

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15
Q

The diagram below shows the electron pair in the C-X bond moving to the halogen atom (X). What does the halogen atom become?

A

A halide ion

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16
Q

What is the halide ion called?

A

The leaving group

17
Q

What does the rate of substitution depend on?

A

The halogen

18
Q

Which of the halogens is unreactive?

A

Flourine

19
Q

Why are flouro-compounds unreactive?

A

Because of the strength of the C-F bond

20
Q

The rate of reaction increases going….(up or down the halogen group)?

A

Down the halogen group

21
Q

Why dies the rate of reaction increase going down the halogen group?

A

because the strength of the C-X bond decreases.

22
Q

The reaction of halogenoalkanes and the hydroxide ion is very slow in room temperature. What can be done to speed up the rate of reaction?

A

Warm the mixture

23
Q

Halogenoalkanes do not mix with water. So what is used instead as a solvent in which both the halogenoalkane and the hydroxide ion can both mix.

A

Ethanol

24
Q

Name the reaction between a halogenoalkane and hydroxide ion in ethanol

A

Hydrolysis

25
Q

Write the general formula between a halogenoalkane and a hydroxide ion

A

R-X + OH- → ROH + X-

26
Q

What is the functional group ROH that is formed?

A

An alcohol

27
Q

Write the formula for the reaction of bromoethane and and a hydroxide ion

A

C2H5Br + OH- → C2H5OH + Br

28
Q

Draw the mechanism for the reaction of bromoethane and and a hydroxide ion

A

Check pg 209

29
Q

Describe the conditions for the reaction of a halogenoalkane and the cyanide ion

A

Warm and in a alcoholic solution

30
Q

What is produced in the reaction between a halogenoalkane and the cyanide ion?

A

A nitrile

31
Q

Draw the mechanism for the reaction of a halogenoalkane and a cyanide ion

A

Check pg 209

32
Q

Describe the conditions for the reaction of a halogenoalkane and ammonia

A

In ethanol and under pressure

33
Q

What is produced in the reaction between a halogenoalkane andammonia?

A

an amine

34
Q

Write out the formula for the reaction of a halogenoalkane and ammonia

A

R-X + 2NH3 → RNH2 + NH4X

35
Q

Draw the mechanism for the reaction of a halogenalkane and ammonia

A

Check pg 210

36
Q

Why does the reaction of a halogeonalkane and ammonia have a third step?

A

Because ammonia is a neutral nucleophile a H+ must be lost to form a neutral product, called amine.

AQA chemistry (13, Halogenoalkanes) (3 decks)

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