U3-3 - Synthesis Flashcards by Miss Peciulyte | Brainscape

Q

What does a double headed arrow mean in a mechanism?

A

A pair of electrons is transferred

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

What determines which element gets the bond electrons (and a negative charge)?

A

More electronegative atom gets the electrons.

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Nucleophile

A

Negatively charged ion or neutral e⁻ rich molecule

(e.g. OH^–, NH₃)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Electrophile

A

Positively charged ion or neutral e⁻ deficient molecule

(e.g. H⁺)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

In a mechanism, should the head of a curly arrow point at the nucleophile or electrophile?

A

Electrophile

(from negative to positive)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Substitution reaction

A

A reaction where a functional group is replaced by a different one.

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Elimination reaction

A

A reaction where a small molecule is removed from the reactant molecule (e.g. HCl or H₂O).

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

What is this type of molecule called?

A

Haloalkane

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

What feature of haloalkanes allows nucleophiles to attack them?

A

Carbon-halogen bond is polar.

(Nucleophile can attack C)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Why is this type of reaction significant in chemistry?

A

Increases length of carbon chain

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Name this type of reaction

A

Acid (catalysed) hydrolysis

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Carbocation

A

A species with a positively charged carbon atom.

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Which type of carbocations are the least stable?

A

Primary

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Why are tertiary carbocations the most stable?

A

Due to the inductive effect.

(Alkyl groups push e⁻ density towards the positively charged C atom, which stabilises the charge.)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

What do the numbers refer to in S_N1 and S_N2?

A

Number of molecules in RDS

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Step 1 of S_N1

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Step 1 of S_N1 - draw in curly arrow(s)

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

S_N1 step 2 - draw in curly arrow(s)

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Which step is the slow (RDS) step in S_N1?

Step 1 - Carbocation formation

Step 2 - Substitution

A

Step 1 - Carbocation formation

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

S_N2 - draw in curly arrow(s)

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

S_N2

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

What is missing in this transition state?

A

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Which mechanism forms an inverted product:

S_N1 or S_N2?

A

S_N2

(Attacking group is always opposite to where the leaving group was.)

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Which mechanism forms a racemic mixture:

S_N1 or S_N2?

A

S_N1

(Attacking group can attach to either side of carbocation.)

Q

When is S_N1 preferred over S_N2?

A

Stable carbocation (tertiary)

(or steric hindrance)

Q

When is S_N2 preferred over S_N1?

A

Less stable carbocation (primary)

Q

When a primary alcohol is oxidised, the product is…

A

an aldehyde/carboxylic acid.

Q

When a secondary alcohol is oxidised, the product is …

A

a ketone.

Q

How can alcohols be made from haloalkanes?

A

(Heated under reflux with) aqueous KOH or NaOH

Q

A

Q

A

Q

A

Q

A

Q

Suggest a possible oxidising agent to oxidise an alcohol.

A

Copper(II) oxide OR acidified potassium dichromate

Q

LiAlH₄ acts as a …

A

reducing agent.

Q

What type of substance is this?

R–O^–

A

Alkoxide

(acts as a base)

Q

To make an alkoxide from an alcohol, react the alcohol with …

A

an alkali metal (Na/K).

Q

Name this type of compound.

A

Acid chloride

Q

Alcohols react with ______ or _____ to make esters.

A

carboxylic acids or acid chlorides

Q

What is an advantage of using acid chlorides over carboxylic acids in ester synthesis?

A

No catalyst required

Q

Alcohol + Carboxylic acid → Ester + Water

Name the catalyst used

A

Conc. sulfuric acid

Q

___________ are isomers of alcohols.

A

Ethers

Q

Why are ether boiling points lower than alcohol boiling points?

A

Lack of H-bonding between ether molecules.

Q

Alcohols can be dehydrated using ____________ to catalyse the reaction.

A

hot Al₂O₃ or conc. H₂SO₄ or H₃PO₄

Q

Name this type of reaction

A

Elimination/dehydration

Q

Which is the major product?

A

But-2-ene

Q

How do you turn a haloalkane into an alkene?

A

React with ethanolic KOH or NaOH.

(NOT aqueous or you’ll make an alcohol)

Q

Name this type of reaction

A

(Electrophilic) addition

Q

Why does the Br₂ molecule become polarised (acquire partial charges)?

A

The e⁻ rich C=C bond pushes away the e⁻ in Br₂ to one side (one Br), making one Br^δ+ and one Br^δ−.

Q

Step 1 of alkene halogenation

A

Q

Step 1 of alkene halogenation

A

Q

Step 2 of alkene halogenation

A

Q

Alkene + hydrogen halide

A

Q

Alkene + hydrogen halide

A

Q

Why is 2-bromopropane the major product (and not 1-bromopropane)?

A

More stable carbocation formed

Q

Primary, secondary or tertiary?

A

Secondary

Q

Primary, secondary or tertiary?

A

Tertiary

Q

Primary, secondary or tertiary?

A

Primary

Q

Name this type of compound

A

Amine

Q

Which is the most water soluble and why?

A

Primary, can form the most H-bonds

Q

Which has the lowest boiling point and why?

A

Tertiary, can’t form H-bonds between amine molecules (but can with water)

Q

What is the role of AlCl₃?

A

Catalyst

Q

Suggest a catalyst for chlorination of benzene

(Chlorination = substitute H with Cl on the ring)

A

AlCl₃ or FeCl₃

Q

Suggest a catalyst for bromination of benzene

(Bromination = substitute H with Br on the ring)

A

AlBr₃ or FeBr₃

Q

State nitrating mixture used

A

Q

Suggest source of sulfonate ions, HSO₃⁺

A

Q

Suggest how the alkyl group (e.g. CH₃⁺) is generated.

A

Basically, haloalkane with required alkyl group, plus AlCl₃ catalyst.