11 - alcohols Flashcards by Ben Chapman

What is the alcohol functional group?

OH (Hydroxyl group)

How well did you know this?

Not at all

Perfectly

What is the general formula of alcohols?

C~n H~(2n + 2) O

How well did you know this?

Not at all

Perfectly

When is an alcohol a primary alcohol?

When the OH is only attached to one alkyl group.

How well did you know this?

Not at all

Perfectly

When is an alcohol secondary?

When the carbon that the OH is on is attached to two alkyl groups

How well did you know this?

Not at all

Perfectly

When is an alcohol tertiary?

When the carbon that the OH is on is attached to three alkyl groups

How well did you know this?

Not at all

Perfectly

What state does ethanol have at room temperature?

liquid

How well did you know this?

Not at all

Perfectly

Why do alcohols have a higher boiling point than alkanes?

The OH group has a dipole (H has delta positive)

How well did you know this?

Not at all

Perfectly

What is volatility?

How easily a substance evaporates

How well did you know this?

Not at all

Perfectly

How does volatility change as boiling point changes?

Volatility decreases as boiling point increases

How well did you know this?

Not at all

Perfectly

What is the volatility of alcohols like compared to alkanes and why?

alcohols have a low volatility compared to alkanes

Due to hydrogen bonds

How well did you know this?

Not at all

Perfectly

Do alcohols dissolve in water?

Explain

They do dissolve in water

Because they are polar due to their hydrogen bonds

How well did you know this?

Not at all

Perfectly

How does chain length affect solubility and why?

As chain length increases, solubility decreases

Because hydrocarbon chain is not polar and can’t make hydrogen bonds with water

How well did you know this?

Not at all

Perfectly

What is an oxidising agent?

A reagent which provides the oxygen in a reaction

How well did you know this?

Not at all

Perfectly

In the oxidation of alcohols

What is the oxidising agent?

Acidified potassium dichromate

H+ | K~2 Cr~2 O~7

How well did you know this?

Not at all

Perfectly

What are the 2 oxidation reactions that can be done on primary alcohols?

Distillation

Reflux

How well did you know this?

Not at all

Perfectly

What is formed when primary alcohols are oxidised by distillation?

Aldehyde and water

How well did you know this?

Not at all

Perfectly

How do you draw aldehydes?

One of the END carbons must have a C=O instead of one if its C-H bonds

How well did you know this?

Not at all

Perfectly

How do you write the equation for the oxidation of an alcohol by distillation?

Draw out the alcohol

Then put + [O]

Then draw the reaction arrow with H+ | K~2 Cr~2 O~7 above it and “distillation” below it

Draw the aldehyde with the same number of carbons as the alcohol

Then put + H~2 O

What are the observations of all primary alcohol oxidation reactions?

Acidified potassium dichromate goes from orange to green

What is the naming system for aldehydes?

al suffix

e. g. Ethanol goes to ethanal

What is the aldehyde functional group?

CHO

What is produced when alcohols are oxidised by reflux?

Carboxylic acid and water

What type of alcohol do you need to use to get carboxylic acids?

A primary alcohol must be used under reflux

How do you draw carboxylic acids?

Put a C-OH

And C=O

On the end carbon

How do you write the equation for reflux oxidising alcohols?

Draw the alcohol Put + 2[O] Draw the reaction arrow with H+ | K~2 Cr~2 O~7 above and reflux below Draw the carboxylic acid Write + H~2 O

What is the functional group of carboxylic acids?

COOH

What is the observation when oxidising secondary alcohols?

Still colour change from orange to green

What is a ketone?

Like an aldehyde but the C=O is on a middle carbon (not end carbon) when finding an isomer of a ketone, you can't put the C=O on an end carbon because that would be an aldehyde

What is the functional group for ketones?

RCOR R just means other stuff (usually an alkyl group)

What are the types of reaction for oxidising secondary alcohols?

There's only one Applying heat

How do you name ketones?

- one is the suffix | e. g. pentan-2-one

How do you write the reaction for oxidation of secondary alcohols?

Draw an alcohol where the OH isn't on an end carbon Put + [O] Put a reaction arrow with H+ | K~2 Cr~2 O~7 above it and "heat" below it Draw the ketone Put + H~2 O

Describe the dehydration of alcohols

An alcohol is heated with a reagent of CONCENTRATED H~2 SO~4 and heat An alkene and water is produced This is an elimination reaction

With dehydration of alcohols, what is different when secondary alcohols are used?

2 different alkenes are produced With the double bond on the left of where the OH was And with the double bond on the right of where the OH was

What is the basic idea of what happens in an alcohol substitution reaction?

The OH of the alcohol is substituted by a halogen to form a haloalkane

What are the conditions and reagents of alcohol substitution?

Reflux the alcohol With sulphuric acid and sodium halide (The halide contains the halogen that we want in the haloalkane)

Why is a sodium halide used in substitution of alcohols?

The hydrogen halide on its own doesn't work for some reason

What is the first reaction which happens in substitution of alcohols?

NaX + H~2 SO~4 --> NaHSO~4 + HX Where X is the halogen

What is the second reaction which happens in substitution of alcohols? Use ethanol as the alcohol

C~2 H~6 O + HX --> C~2 H~5 X + H~2 0 Where X is the halogen

What is the overall reaction of alcohol substitution? Use propanol as the alcohol and chlorine as the halogen

C~3 H~8 O + NaCl + H~2 SO~4 --> C~3 H~7 Cl + NaHSO~4 + H~2 O

What does a nitrile contain?

A triple bond

How do you draw cyanide?

C triple bond N Put a lone pair on the C

Why are the boiling points of branched alcohols less than boiling points of straight chain alcohols? 2 marks

Less points of contact between branched alcohols So less energy required to break London forces in branched alcohols