alcohols handout

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AS Chemistry AS Chemistry F322: Chains, Energy & Resources F322: Chains, Energy & Resources

2.2.1 Alcohols

Alcohols.

P.J.McCormack P.J.McCormack

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1. IntroductionIntroduction

The alcohols are a group of organic compounds that contain one or more

The alcohols are a group of organic compounds that contain one or more hydroxyhydroxy groups, (-OH) groups, (-OH) attached to an alkyl group in a covalent structure.

attached to an alkyl group in a covalent structure. Monohydric

Monohydric alcohols containalcohols contain only one –OH group per moleculeonly one –OH group per molecule.. PolyhydricPolyhydric alcohols contain alcohols contain more than one –OH group per molecule

more than one –OH group per molecule. Polyhydric alcohols are more viscous and have higher. Polyhydric alcohols are more viscous and have higher boiling points than monohydric alcohols because the degree of hydrogen bonding is much greater. boiling points than monohydric alcohols because the degree of hydrogen bonding is much greater. The general formula of a simple alcohol is

The general formula of a simple alcohol is

C

_n_n

H

_2n+1_2n+1

OH:

R-OH

The alcohols represent an important group of compounds. Their uses vary from alcoholic drinks to The alcohols represent an important group of compounds. Their uses vary from alcoholic drinks to solvents, antifreeze, fuels and cosmetics.

solvents, antifreeze, fuels and cosmetics. Naming Alcohols

Naming Alcohols

The name of an alcohol consists of a first part, which indicates the chain length (methan, ethan, propan The name of an alcohol consists of a first part, which indicates the chain length (methan, ethan, propan etc.). This stem is followed by the suffix –

etc.). This stem is followed by the suffix – olol. Thus CH. Thus CH33-OH is methanol and CH-OH is methanol and CH33CHCH22-OH is ethanol.-OH is ethanol.

For chain lengths of three or more carbon atoms, the alcohols have numbers to indicate the position of For chain lengths of three or more carbon atoms, the alcohols have numbers to indicate the position of the –OH group along the carbon chain. The numbering of the carbon chain starts at the end of the chain the –OH group along the carbon chain. The numbering of the carbon chain starts at the end of the chain closest to the first substituted group, -OH. So CH

closest to the first substituted group, -OH. So CH33CHCH22CHCH22OH is propan-1-ol and CHOH is propan-1-ol and CH33CH(OH)CHCH(OH)CH33 is is

propan-2-ol: propan-2-ol:

Propan-1-ol Propan-2-ol

When the numbering could begin at either end, due to

When the numbering could begin at either end, due to two substituted groupstwo substituted groups, it starts at the end, it starts at the end nearest the substituted group that comes first alphabetically – CH

nearest the substituted group that comes first alphabetically – CH33CH(CCH(C22HH55)CH(OH)CH)CH(OH)CH33 is is

2-ethylbutan-3-ol i.e. 2-ethylbutan-3-ol i.e.

Alkyl

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2.2.1 (a) – Physical Properties of Alcohols 2.2.1 (a) – Physical Properties of Alcohols

The physical properties of alcohols are explained in terms of intermolecular forces; hydrogen bonding The physical properties of alcohols are explained in terms of intermolecular forces; hydrogen bonding .and van der Waals in

.and van der Waals interactions.teractions. Hydrogen bonding.

Hydrogen bonding.

Hydrogen bonding occurs between molecules where a hydrogen atom attached to a very Hydrogen bonding occurs between molecules where a hydrogen atom attached to a very electronegative eleme

electronegative element such as fluorine, oxnt such as fluorine, ox ygen or nitrogen. In the case of alcohols, there are hydrogenygen or nitrogen. In the case of alcohols, there are hydrogen bonds set up between the slightly positive hydrogen (

bonds set up between the slightly positive hydrogen (δδ_{+) atoms and lone pair of}_{+) atoms and lone pair of electrons on oxygen (}_{electrons on oxygen (}δδ

--) in other molecules. The hydrogen atoms are slightly positive because the bonding electrons are pulled ) in other molecules. The hydrogen atoms are slightly positive because the bonding electrons are pulled away from them towards the very electronegative oxygen atoms.

away from them towards the very electronegative oxygen atoms.

The hydroxy, -OH, functional group in The hydroxy, -OH, functional group in alcohols enables them to form

alcohols enables them to form hydrogenhydrogen bonds

bonds i.e. the hydrogen is attached to an i.e. the hydrogen is attached to an electronegative atom (O) that has two lone electronegative atom (O) that has two lone pairs of electrons. Alcohols, consequently, can pairs of electrons. Alcohols, consequently, can form hydrogen bonds with themselves and form hydrogen bonds with themselves and with water.

with water.

In water the two hydrogen atoms in

In water the two hydrogen atoms in a water molecule can form two hydrogen a water molecule can form two hydrogen bonds to two oxygenbonds to two oxygen atoms in

atoms in twotwo other water molecules.other water molecules.

However, in alcohols there is only

However, in alcohols there is only oneone hydrogenhydrogen atom able to form hydrogen bonds and so there is atom able to form hydrogen bonds and so there is less hydrogen bonding

less hydrogen bonding in alcohols. As a in alcohols. As a

consequence of this the boiling points of methanol consequence of this the boiling points of methanol (M

(Mrr= 32) and ethanol (M= 32) and ethanol (Mrr=46) are much lower than=46) are much lower than

water. water. Hydrogen bonding between two

Hydrogen bonding between two alcohol molecules

alcohol molecules

Hydrogen bonding in water Hydrogen bonding in water

Hydrogen bonding between ethanol and water Hydrogen bonding between ethanol and water

Exam Tip:

Exam Tip: Explain all Explain all physical properties in terms physical properties in terms of hydrogen bonding

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Nevertheless, the hydrogen bonding between alcohol molecules is still very significant and

Nevertheless, the hydrogen bonding between alcohol molecules is still very significant and alcoholsalcohols have higher boiling points than the equivalent alkanes.

have higher boiling points than the equivalent alkanes. Volatility.

Volatility. Trend:

Trend: The volatility decreases with increasing carbon chain length. The volatility decreases with increasing carbon chain length. Explanation

Explanation: Alcohols are relatively low volatile compounds as they possess: Alcohols are relatively low volatile compounds as they possess hydrogen bonds between the molecules, resulting i

hydrogen bonds between the molecules, resulting in more energy required to separate the moleculesn more energy required to separate the molecules when compared to alkanes.

when compared to alkanes.

Alcohols are less volatile than alkanes due to alcohols having hydrogen bonds between the molecules Alcohols are less volatile than alkanes due to alcohols having hydrogen bonds between the molecules whereas alkanes have

whereas alkanes have weaker van der weaker van der Waals interactions. Waals interactions. Hydrogen bonds are strHydrogen bonds are stronger intermolecularonger intermolecular bonds than van der Waals resulting in more energy required to separate the alcohol molecules from bonds than van der Waals resulting in more energy required to separate the alcohol molecules from each other.

each other. Boiling Points. Boiling Points. Trend:

Trend: The boiling point of alcohols increases with increasing an incr The boiling point of alcohols increases with increasing an incr ease in carbon chain length.ease in carbon chain length. Explanation:

Explanation:. As the carbon chain length increases there is the same amount of hydrogen bonding but. As the carbon chain length increases there is the same amount of hydrogen bonding but an increase in the amount van

an increase in the amount van der Waals interaction due to an der Waals interaction due to an increased surface area of the molecules.increased surface area of the molecules.

The table below shows the comparison of the boiling points of alcohols and

The table below shows the comparison of the boiling points of alcohols and equivalent alkanes in termsequivalent alkanes in terms of carbon chain length.

of carbon chain length.

Volatile

Volatile – the ease at – the ease at which a liquid which a liquid evaporates. evaporates. Van der Van der Waals Waals interactions interactions

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The boiling points depend on intermolecular forces (between molecules). Alkanes only have van der The boiling points depend on intermolecular forces (between molecules). Alkanes only have van der Waal’s forces between their molecules, whereas alcohols have both

Waal’s forces between their molecules, whereas alcohols have both van der Waal’s forces and van der Waal’s forces and hydrogenhydrogen bonding. bonding. �� 00 � � �� 00 � � � � ��

Although ethane and methanol are of similar size (in terms of molecular mass) the contribution of the Although ethane and methanol are of similar size (in terms of molecular mass) the contribution of the hydrogen bonding in methanol means that its boiling point is much higher.

hydrogen bonding in methanol means that its boiling point is much higher.

The boiling points of alcohols are also affected by isomerism. If the –OH group is

The boiling points of alcohols are also affected by isomerism. If the –OH group is moved to the centremoved to the centre of the carbon chain the

of the carbon chain the molecule becomes more spherical, with a smaller molecule becomes more spherical, with a smaller surface area. This reduces thesurface area. This reduces the van der Waal’s forces. It also makes the –OH less accessible and reduces hydrogen bonding. Butan-1-ol van der Waal’s forces. It also makes the –OH less accessible and reduces hydrogen bonding. Butan-1-ol has a boiling point of 117

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Water Solubility. Water Solubility.

Hydrogen bonding in the smaller molecules of alcohols enables them to dissolve easily in water Hydrogen bonding in the smaller molecules of alcohols enables them to dissolve easily in water (miscible). However, as the hydrocarbon chain length increases the solubility rapidly decreases. This is (miscible). However, as the hydrocarbon chain length increases the solubility rapidly decreases. This is because the longer hydrocarbon chains form stronger van der Waal’s forces between themselves rather because the longer hydrocarbon chains form stronger van der Waal’s forces between themselves rather than with the water.

than with the water. Name

Name Formula Formula Solubility Solubility g/100g g/100g HH22OO

Methanol CH Methanol CH33OH OH ∞∞ Ethanol CH Ethanol CH₃₃CHCH₂₂OH OH ∞∞ Propan-1-ol CH Propan-1-ol CH33CHCH22CHCH22OH OH ∞∞ Butan-1-ol CH Butan-1-ol CH33CHCH22CHCH22CHCH22OH OH 7.97.9 Pentan-1-ol CH Pentan-1-ol CH33CHCH22CHCH22CHCH22CHCH22OH OH 2.42.4 Hexan-1-ol CH Hexan-1-ol CH33CHCH22CHCH22CHCH22CHCH22CHCH22OH OH 0.60.6 2.2.1 (b) – Preparation of Ethanol 2.2.1 (b) – Preparation of Ethanol (i)

(i) Fermentation.Fermentation.

About 5% of the world’s production of ethanol is p

About 5% of the world’s production of ethanol is produced by fermentation. This process is carried outroduced by fermentation. This process is carried out by yeast in the presence of glucose but in the absence of air (anaerobic respiration). The weak ethanol by yeast in the presence of glucose but in the absence of air (anaerobic respiration). The weak ethanol solution produced (5 – 15%) can be converted into ethanol by distillation (boili

solution produced (5 – 15%) can be converted into ethanol by distillation (boili ng point 78ng point 78ooC)C) If oxygen is present then the yeast

If oxygen is present then the yeast converts the glucose (carbohydrate) into carboxylic acid (ethanoic acid) ratherconverts the glucose (carbohydrate) into carboxylic acid (ethanoic acid) rather than ethanol. Oxidation occurs rather

than ethanol. Oxidation occurs rather than fermentation.than fermentation. The enzyme

The enzyme zymasezymase in yeast converts the glucose into ethanol and carbon dioxide: in yeast converts the glucose into ethanol and carbon dioxide:

C

₆₆

H

₁₂₁₂

O

₆₆

(aq)

2 C

₂₂

H

₅₅

OH(aq) + 2CO

₂₂

(g)

The main use of fermentation is the production of alcoholic drinks but it is

The main use of fermentation is the production of alcoholic drinks but it is also becoming an importantalso becoming an important way of producing car fuel (Brazil – sugar cane).

way of producing car fuel (Brazil – sugar cane). This process has a number of advantages: This process has a number of advantages:

--

it is a low-technology process, which means it can be used anywhereit is a low-technology process, which means it can be used anywhere

--

it does not use much energyit does not use much energy

--

it uses sugar cane as a raw material, which is a renewable resourceit uses sugar cane as a raw material, which is a renewable resource

east east 37 37°°_C_C

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There are, however, a few disadvantages associated with this

There are, however, a few disadvantages associated with this process:process:

--

it is a batch process, which means that once the reaction has finished the vessel needs toit is a batch process, which means that once the reaction has finished the vessel needs to

emptied before the reaction can be started emptied before the reaction can be started againagain

--

it is a relatively slow processit is a relatively slow process

--

it produces fairly impure ethanolit produces fairly impure ethanol

(ii)

(ii) Reaction of Ethene with SteamReaction of Ethene with Steam

In those countries, which have good supplies of crude oil or n

In those countries, which have good supplies of crude oil or n atural gas, ethanol, for industrial use, isatural gas, ethanol, for industrial use, is made from ethene.

made from ethene.

The ethene is produced by

The ethene is produced by crackingcracking. This is a process in which l. This is a process in which large molecules are broken downarge molecules are broken down into smaller (and more useful) molecules by heating the oil in the presence of a catalyst (Al

into smaller (and more useful) molecules by heating the oil in the presence of a catalyst (Al22OO33).).

The ethene and steam are passed over a

The ethene and steam are passed over a phosphoric acid (Hphosphoric acid (H33POPO44) catalyst, at about 300) catalyst, at about 300 0 0

C C and 60 atmospheres pressure

and 60 atmospheres pressure.. The reaction is called hydration.The reaction is called hydration.

2.2.1 (c) Uses of Ethanol 2.2.1 (c) Uses of Ethanol

Ethanol has a variety of uses including Ethanol has a variety of uses including

•

• _{Alcoholic drinks}_{Alcoholic drinks} •

• _{As a fuel}_{As a fuel} •

• _{As a solvent}_{As a solvent} •

• _{In cosmetics manufacture}_{In cosmetics manufacture} •

• _{As an intermediate in the manufacture of}_{As an intermediate in the manufacture of many other chemicals}_{many other chemicals}

Wines and beers produced by fermentation are coloured and flavoured by substances from the starting Wines and beers produced by fermentation are coloured and flavoured by substances from the starting material or by other products of

material or by other products of the fermentation (or added, like hops fothe fermentation (or added, like hops for ‘bitter’ beer). Fermentedr ‘bitter’ beer). Fermented brews can contain up to 5 – 15%

brews can contain up to 5 – 15% by volume of ethanol. At this concentration, yeast is killed andby volume of ethanol. At this concentration, yeast is killed and fermentation stops.

fermentation stops.

‘Spirits’ are made by the inefficient distillation of the fermented liquid, to raise the alcohol proportion ‘Spirits’ are made by the inefficient distillation of the fermented liquid, to raise the alcohol proportion toto 30 – 45%. Whisky is obtained by distill

30 – 45%. Whisky is obtained by distilling a mixture similar to beer, brandy is made from wine anding a mixture similar to beer, brandy is made from wine and vodkas from fermented mashed potato.

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Most spirits have a strength of around 40%. Occasionally the old term ‘degrees proof’ is used. A 100% Most spirits have a strength of around 40%. Occasionally the old term ‘degrees proof’ is used. A 100% proof spirit contains about 52% of alcohol.

proof spirit contains about 52% of alcohol.

The production of ethanol is becoming important as a way of producing alternative car fuel, especially in The production of ethanol is becoming important as a way of producing alternative car fuel, especially in those countries with limited oil reserves. ‘Gasohol’ contains up to 20% ethanol in lead-free petrol; car those countries with limited oil reserves. ‘Gasohol’ contains up to 20% ethanol in lead-free petrol; car performance is hardly affected. In Brazil production from some sugar cane plantations is used exclusively performance is hardly affected. In Brazil production from some sugar cane plantations is used exclusively for this purpose.

for this purpose.

Methanol is also used as a petrol additive to improve combustion and its increasing importance as a Methanol is also used as a petrol additive to improve combustion and its increasing importance as a feedstock in the production of organic chemicals. It is cheap and burns with

feedstock in the production of organic chemicals. It is cheap and burns with a cleaner flame than thea cleaner flame than the hydrocarbons used in petrol. However, volume for volume it produces less energy, so bigger fuel tanks hydrocarbons used in petrol. However, volume for volume it produces less energy, so bigger fuel tanks would be needed. It also absorbs water, it is hygroscopic, so it corrodes parts of the

would be needed. It also absorbs water, it is hygroscopic, so it corrodes parts of the engine.engine.

Alcohols are used as a solvent in a variety of compounds. Ethanol is made into methylated spirit by the Alcohols are used as a solvent in a variety of compounds. Ethanol is made into methylated spirit by the addition of the more toxic methanol plus a purple dye.

addition of the more toxic methanol plus a purple dye. 2.2.1 (d) Classification of

2.2.1 (d) Classification of Alcohols.Alcohols. Alcohols can be divided into

Alcohols can be divided into three classesthree classes depending on the depending on the number of alkyl groupsnumber of alkyl groups linked to the linked to the carbon that is attached to the O-H group.

carbon that is attached to the O-H group. The three classes are calledThe three classes are called primary, secondaryprimary, secondary andand tertiary alcohols

tertiary alcohols.. Primary

Primary alcohols contain the –CH alcohols contain the –CH22OH group. They have a maximum ofOH group. They have a maximum of one other alkylone other alkyl group group (R)(R)

linked to the carbon attached to the

linked to the carbon attached to the –OH group e.g.–OH group e.g.

Secondary

Secondary alcohols alcohols contain contain the the CHOH CHOH group. group. They They havehave two alkyl groupstwo alkyl groups linked to the carbon linked to the carbon atom that is attached to the –OH group

atom that is attached to the –OH group e.g.e.g. Ethanol

Ethanol _Propan-1-ol_Propan-1-ol

Propan-2-ol

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Tertiary

Tertiary alcohols contain the -COH alcohols contain the -COH group. They havegroup. They have three alkyl groupsthree alkyl groups linked to the carbon atomlinked to the carbon atom that is attached to the –OH group e.g.

that is attached to the –OH group e.g.

2.2.1 (e) Combustion of

2.2.1 (e) Combustion of Alcohols.Alcohols. In a plentiful supply of oxygen alcohols bu

In a plentiful supply of oxygen alcohols burn very readily to form carbon dioxide and water.rn very readily to form carbon dioxide and water. C

C22HH55OH(g) + 3OOH(g) + 3O22(g)(g) →→→→→→→→ 2CO2CO22(g) + 3H(g) + 3H22O(g)O(g)

In a limited amount of oxygen alcohols combust to form carbon monoxide and water. In a limited amount of oxygen alcohols combust to form carbon monoxide and water.

C

C₂₂HH₅₅OH(g) +OH(g) +

2

OO₂₂(g)(g) →→→→→→→→_{2CO(g) + 3H}_{2CO(g) + 3H}

2 2O(g)O(g)

2.2.1(f) Oxidation of Alcohols. 2.2.1(f) Oxidation of Alcohols.

Primary and secondary alcohols can be oxidised using an oxidisin

Primary and secondary alcohols can be oxidised using an oxidisin g agent. The oxidising agent used tog agent. The oxidising agent used to oxidise primary and secondary alcohols is

oxidise primary and secondary alcohols is potassium dichromatepotassium dichromate (K (K₂₂CrCr₂₂OO₇₇) in acidic conditions (H) in acidic conditions (H++_)._).

The acid used to acidify potassium dichromate is

The acid used to acidify potassium dichromate is sulfuric acidsulfuric acid (H (H22SOSO44). During oxidation of alcohols). During oxidation of alcohols

water is always produced. water is always produced.

Potassium dichromate is an orange colour and changes to a green colour during the reaction. Potassium dichromate is an orange colour and changes to a green colour during the reaction.

(i)

(i) Oxidation of Primary AlcoholsOxidation of Primary Alcohols On gentle heating

On gentle heating primary alcoholsprimary alcohols are oxidised to an are oxidised to an aldehydealdehyde. The symbol [O] is used to. The symbol [O] is used to represent an oxidising agent in the equation. Gentle heating involves distillation where the product of represent an oxidising agent in the equation. Gentle heating involves distillation where the product of the reaction, the aldehyde is removed as it is formed, which p

the reaction, the aldehyde is removed as it is formed, which p revents further oxidation to the carboxylicrevents further oxidation to the carboxylic acid. acid. 2-methyl butan-2-ol 2-methyl butan-2-ol 2-methyl propan-2-ol 2-methyl propan-2-ol

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Oxidation of primary alcohols produces an aldehyde, then further oxidation will produce a carboxylic Oxidation of primary alcohols produces an aldehyde, then further oxidation will produce a carboxylic acid.

acid.

On strong heating of a

On strong heating of a primary alcohoprimary alcohol al a carboxylic acidcarboxylic acid is formed. is formed.

Reflux:

Reflux: The continual boiling and condensing of a reaction mixture to ensure the reaction goes to The continual boiling and condensing of a reaction mixture to ensure the reaction goes to completion without the mixture billing dry.

completion without the mixture billing dry. http://goo.gl/cdsEV

http://goo.gl/cdsEV

Distillation:

Distillation: The process of separating a mixture of liquids due to the difference in boiling points.The process of separating a mixture of liquids due to the difference in boiling points. http://goo.gl/pbmXr

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(ii)

(ii) Oxidation of Secondary Alcohols.Oxidation of Secondary Alcohols. Oxidation of a

Oxidation of a secondarysecondary alcohol produces a alcohol produces a ketoneketone. The same oxidising agent is used as for primary. The same oxidising agent is used as for primary alcohols,

alcohols, acidified potassium dichromateacidified potassium dichromate (H (H++/K/K22CrCr22OO77), where H), where H + +

= H = H22SOSO44..

(iii)

(iii) Oxidation of Tertiary Alcohols.Oxidation of Tertiary Alcohols.

Tertiary alcohols cannot be oxidised. No reaction occurs with acidified potassium dichromate; the Tertiary alcohols cannot be oxidised. No reaction occurs with acidified potassium dichromate; the oxidising agent remains the same colour,

oxidising agent remains the same colour, orange.orange.

2.2.1 (g) – Esterification 2.2.1 (g) – Esterification..

When an alcohol reacts with a carboxylic acid in the presence of a concentrated acid catalyst an ester is When an alcohol reacts with a carboxylic acid in the presence of a concentrated acid catalyst an ester is formed. The reaction is called

formed. The reaction is called esterificationesterification. Esters have the functional group –COO-. Esters have the functional group

–COO-e.g. methyl ethanoate e.g. methyl ethanoate

The acid catalyst used during esterification is

The acid catalyst used during esterification is concentratedconcentrated sulfuric acid

sulfuric acid (H (H22SOSO44) which can be abbreviated to H) which can be abbreviated to H + +

..

The general equation for esterification is: The general equation for esterification is:

Carboxylic

Carboxylic Acid Acid + + AlcoholAlcohol →→→→→→→→ _Ester_Ester ₊₊ _Water_Water

Oxidation of a secondary alcohol Oxidation of a secondary alcohol

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During esterification water is produced fr

During esterification water is produced from the -OH of the carboxylic om the -OH of the carboxylic acid and the -H from theacid and the -H from the alcohol. Esters have a fruity aroma and are used for flavourings and fragrances in food and p

alcohol. Esters have a fruity aroma and are used for flavourings and fragrances in food and p erfumes.erfumes. They are also are used as adhesives and solvents in the chemical industry.

They are also are used as adhesives and solvents in the chemical industry. 2.2.1 (h) – Elimination of Water from Alcohols.

2.2.1 (h) – Elimination of Water from Alcohols. Alcohols can be dehydrated (lose water) to

Alcohols can be dehydrated (lose water) to form an alkene by heating thform an alkene by heating them with a catalyst. The reactionem with a catalyst. The reaction mechanism for this reaction is called

mechanism for this reaction is called eliminationelimination.. The catalyst used in

The catalyst used in concentrated concentrated phosphoric acid (H phosphoric acid (H33POPO44)) or or concentrated concentrated sulfuric acid sulfuric acid

(H

(H₂₂SOSO₄₄).). The alcohol is heated under reflux to produce an alkene. The alcohol is heated under reflux to produce an alkene.

Elimination of water from ethanol Elimination of water from ethanol

Esterification reaction between ethanoic acid and ethanol Esterification reaction between ethanoic acid and ethanol

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H:\Teaching Documents\Key Stage 5\A-Level Chemistry\F322 Chains

H:\Teaching Documents\Key Stage 5\A-Level Chemistry\F322 Chains Energy and Resources\2.2.1 Alcohols\Alcohols Handout.doc/ Energy and Resources\2.2.1 Alcohols\Alcohols Handout.doc/ P.J.McCormack/ P.J.McCormack/ 2-3-132-3-13

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Additional Reading. Additional Reading.

1.

1. OCR Chemistry AS textbook (Heinemann) pages 148-155OCR Chemistry AS textbook (Heinemann) pages 148-155

2.

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Additional Reading. Additional Reading.

1.

1. OCR Chemistry AS textbook (Heinemann) pages 148-155OCR Chemistry AS textbook (Heinemann) pages 148-155

2.

2. www.chemguide.co.ukwww.chemguide.co.uk

http://goo.gl/MJQ8X

3.

3. A-level Chemistry (Google Books)A-level Chemistry (Google Books)

http://goo.gl/z659l

4.

4. www.knockhardy.org.ukwww.knockhardy.org.uk http://goo.gl/1SyD8

http://goo.gl/1SyD8 - notes - notes http://goo.gl/z9NsM