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Sams Chemistry > Amines > Flashcards

Amines Flashcards

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1
Q

What are the steps in the reduction of nitriles ?

A

Step 1- Halogenoalkanes react with the cyanide ion in aqueous ethanol. The halide ion is replaced
Step 2-the nitrile group can be reduced to primary amines with a nickel / hydrogen (H2) catalyst

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2
Q

How do you produce phenylamine from benzene ?

A

Step 1: Benzene is reacted with a mixture of concentrated nitric acid and concentrated sulfuric acid
Step 2: Nitrobenzene is reduced to phenylamine, using tin and and hydrochloric acid as the reducing agent
The tin and hydrochloric acid react to form hydrogen, which reduces the nitrobenzene by removing oxygen atoms of the NO2 group
Water is produced

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3
Q

Amines react with acid chlorides and acid anhydrides in which mechanism ?

A

Nucleophilic addition elimination

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4
Q

Primary amines can be prepared by the reaction of halogenoalkanes with ammonia or by the reduction of nitriles.

Justify the statement that it is better to prepare primary amines from nitriles rather than from halogenoalkanes

A

With halogenoalkane:

further reaction (of primary amines)

OR

Impure product/mixture of products/lower atom economy

With nitriles

No further reaction

OR

Single product / higher atom economy

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5
Q

A student dissolves a few drops of propylamine in 1 cm3 of water in a test tube.

Give an equation for the reaction that occurs.

Describe what is observed when Universal Indicator is added to this solution.

A

CH3CH2CH2NH2 + H2O ⇌ CH3CH2CH2NH3+ + OH–

Green turns blue

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6
Q

Phenylamine can be prepared by a process involving the reduction of nitrobenzene using tin and an excess of hydrochloric acid.

Give an equation for the reduction of nitrobenzene to form phenylamine. Use [H] to represent the reducing agent.

Explain why an aqueous solution is obtained in this reduction even though phenylamine is insoluble in water.

A

C6H5NO2 + 6[H] → C6H5NH2 + 2H2O

C6H5NH2 present as ionic salt OR C6H5NH3+ (Cl–) OR phenyl ammonium (chloride)

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7
Q

Amines E, F and G are weak bases.

Explain the difference in base strength of the three amines and give the order of increasing base strength.

E= C6H6NH2
F= C6H6CH2CH2NH2
G= C6H6NHCH2CH3
A

(Strength depends on availability of) lone pair on N (atom)

M1

E N (next to ring): (lp) delocalised into ring

M2

(lp) less available (to donate to or to accept a H+)

M3

F or G: N (next to alkyl): (positive) inductive effect/electrons pushed to N

M4

(lp) more available (to donate to or to accept a H+)

M5

order of increasing base strength E

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8
Q

Primary amines can be prepared by the reaction of halogenoalkanes with ammonia or by the reduction of nitriles.
Justify the statement that it is better to prepare primary amines from nitriles rather than from halogenoalkanes.

A 
With halogenoalkane:
further reaction (of primary amines)
OR
Impure product/mixture of products/lower atom economy
Ignore bi-product / yield

With nitriles
No further reaction
OR
Single product / higher atom economy

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9
Q

Aqueous solutions of ammonia, ethylamine and phenylamine are prepared.
Each solution has the same concentration.
Which is the correct order for the pH values of these solutions?

A
ammonia > ethylamine > phenylamine

B
ammonia > phenylamine > ethylamine

C
ethylamine > ammonia > phenylamine

D
ethylamine > phenylamine > ammonia

A

C

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10
Q

Which compound is the strongest base?

A
Ammonia

B
Ammonium chloride

C
Methylamine

D
Phenylamine

A

C

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11
Q

What type of reaction is used to convert (CH3)3N into the cationic surfactant [(CH3)3N(CH2)15CH3]Cl?

A
Bronsted–Lowry acid-base reaction

B
Nucleophilic addition

C
Nucleophilic addition-elimination

D
Nucleophilic substitution

A

D

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12
Q

Suggest why lidocaine hydrochloride is used medically in preference to lidocaine.
Explain your answer.

A

Salt is ionic
Independent marks

(More) soluble (in blood/body fluids/water)

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13
Q

nitrobenzene to phenylamine

what is the reducing agent

A

Sn / HCl

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14
Q

Give a use for phenylamines

A 
making dyes
OR making quaternary ammonium salts
OR making (cationic) surfactants
OR making hair conditioner
OR making fabric softener
OR making detergents
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15
Q 
Compound K (C6H5CH2NH2) is a structural isomer of J (CH3C6H4NH2)
Explain why J is a weaker base than K.
A

lone or electron pair on N. M1
If no mention of lone pair CE = 0

in J spread / delocalised into ring (or not delocalised in K)
Ignore negative inductive effect of benzene. M2

less available (for protonation or donation in J)
M3
OR
in K there is a positive inductive effect / electron releasing). M2
more available (for protonation or donation in K) M3

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16
Q

Cetrimide is used as an antiseptic.
[CH3(CH2)15N(CH3)3]+ Br–

cetrimide
Name this type of compound.
Give the reagent that must be added to CH3(CH2)15NH2 to make cetrimide and state the reaction conditions.
Name the type of mechanism involved in this reaction.

A

M1 Quaternary (alkyl) ammonium salt / bromide

M2 CH3Br or bromomethane

M3        Excess ( CH3Br or bromomethane)
Mention of acid eg H2SO4 OR alkali eg NaOH loses both M2 and M3.

M4 Nucleophilic substitution

17
Q

How do you name secondary or tertiary amides

A

N is designated to the ALKYL groups of the amide

18
Q

Ammonia and methylamine were dissolved in separate samples of water. The two solutions had equal molar concentrations.
State one simple method, other than smell, of distinguishing these solutions.
State what you would observe.

A

Measure pH with a meter

Methylamine would have a higher pH / ammonia would have a lower pH

19
Q

In terms of the intermolecular forces between the polymer chains, explain why polyamides can be made into fibres suitable for use in sewing and weaving, whereas polyalkenes usually produce fibres that are too weak for this purpose.

A

M1 in polyamides - H bonding

M2 in polyalkenes - van der Waals forces
Penalise forces between atoms or van der Waals bonds

M3 Stronger forces (of attraction) in polyamides
Or H bonding is stronger

Sams Chemistry (16 decks)

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