PETROLEUM - JOM KIMIA A+：石油化學(xué)材料

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CARBOXILICACID

GeneralformulaCnH2n+1COOH

Onehydrogenatomisreplacedwithfunctionalgroup–COOH

HO

|║

H—C—C—OH

|

H

Formula:HCOOH

O

║

H—C—OH

Formula:CH3COOH

CARBOXYLGROUP

Whyfamiliesknownascarboxylic‘a(chǎn)cid’

Carboxylgroupplaysavitalroletogivesacidicpropertiestocarboxilicacidfamilies.

CH3COOH

H++CH3COO-

Ethanoicacid

Hydrogenion

Ethanoateion

MolecularandStructuralFormula

n

Name

Molecularformula

Mr

Structural

formula

0

Methanoicacid

C0H2(0)+1COOH

=HCOOH

46

O

║

H—C—OH

1

Ethanoicacid

C1H2(1)+1COOH

=CH3COOH

[C2H4O2]

60

HO

|║

H—C—C—OH

|

H

2

Propanoicacid

C2H2(2)+1COOH

=C2H5COOH

74

HHO

||║

H—C—C—C—OH

||

HH

3

Butanoicacid

Namingcarboxilicacids

C

C

C

O

O

H

H

H

H

H

Carbonnumber1

2

3

Example1:

C

C

COOH

H

H

H

H

C

Longestcontinuouschains:propanoicacid

H

H

H

Attachedalkylgroup:2-methyl

Carboxylcarbon:carbonnumber1

Name:2-methylpropanoicacid

C4H8O2/C3H7COOH

Example2:

CH3

C

COOH

H

C2H5

Longestcontinuouschains:butanoicacid

Carboxylcarbon:carbonnumber1

Name:2-methylbutanoicacid

Attachedalkylgroup:2-methyl

Example3:

C2H5

C

COOH

H

C3H7

Name:2-ethylpentanoicacid

Example4:C3H7

C

COOH

H

C2H5

Name:2-ethylpentanoicacid

EthanoicAsid

Canbepreparedthroughoxidationofanethanol.

Chemicalequation:

CH3CH2OH+2[O]CH3COOH+H2O

Etanolethanoicacid

HH

││

H—C—C—OH

││

HH

HO

│║

H—C—C—OH

│

H

+2[O]

+H2O

K2Cr2O7solutions

+

diluteH2SO4

reflux

Thisiscarriedoutbyrefluxingethanolwithanoxidisingagentsuchasacidifiedpotassiumdichromate(VI)orpotassiummanganate(VII)solution.

Preparationofethanoicacidthroughrefluxing

Tisseltube

Waterout

xxxxxxxxxxxxxx

Labelthediagramplease

Water

in

Liebigcondenser

Roundedbottomflask

Retortstand

Absoluteethanol,C2H5OH+

Acidifiedpotassiumdichromate(VI),K2Cr2O7solution

Heat

Wiregauge

Condenserisusedtopreventthelossofavolatileliquidbyvaporisation.

Thismethodofretainingavolatileliquidduringheatingiscalledrefluxing.

Howtocarryouttheactivity?

PhysicalProperties

-pHlessthan7

-sharporunpleasantsmell

-turnmoistbluelitmuspapertored

-colourlessliquid

ChemicalProperties

AcidProperties

-Onlyhydrogenatominthecarboxylgroup,

[-COOH]canionizeinwatertoproduce

hydrogenions,H+.

CH3COOH

CH3COO-+H+CH3COO-

Ethanoicacid

Hydrogenion

Ethanoateion

Ethanoicacidisaweakacid.Why?

-itdissociatesinwaterpartially,mostof

themoleculesremainunchanged.

Reactionswithmetals

-Diluteethanoicacidreactswithreactive

metal(Zn,Mg,Al)toproduceasaltand

hydrogengas.

2CH3COOH+MgMg(CH3COO)2+H2

Ethanoicacid Magnesiumethanoate

2CH3COOH+ZnZn(CH3COO)2+H2Ethanoicacid Zinkethanoate

6CH3COOH+2Al2Al(CH3COO)3+3H2

Ethanoicacid Aluminiumethanoate

Reactionswithbases

-Diluteethanoicacidneutralizesalkalissuch

assodiumhydroxidesolutiontogivean

organicsaltandwater.

CH3COOH+NaOHCH3COONa+H2O

Ethanoicacid Sodiumethanoate

-Blackcopper(II)oxidepowderdissolvesin

diluteethanoicacid.

2CH3COOH+CuOCu(CH3COO)2+H2O

Ethanoicacid Copper(II)ethanoate

Reactionswithcarbonates

-Diluteethanoicacidreactswithmetal

carbonatestoproduceasalt,carbondioxide

andwater.

2CH3COOH+Na2CO32CH3COONa+CO2+H2O

Ethanoicacid Sodiumethanoate

2CH3COOH+CaCO3Ca(CH3COO)2+CO2+H2O

Ethanoicacid Calciumethanoate

Reactionswithalcohols[Esterification]

Esterification:

Carboxilicacidreactswithalcoholto

produceanesterandwater.

Concentrated

H2SO4

Carboxilicacid+Alcohol———Ester+Water

ConcentratedH2SO4:catalyst

[willdiscussmoreinnextchapter]

Usesofcarboxilicacid:

i.Ethanoicacidisknownasaceticacidsusein;

-Foodflavoring

-Foodpreservatives

-Tomakedrugs,dyes,paintsinsectisides,

plastics

-Tomakeestersforuseasslovents

ii.Methanoicacidisusedtocoagulatelatex.

iii.Benzoicacidsisusedasfoodpreservatives

iv.Fattyacidsusedinmakingsoaps

v.Carboxilicacidsuseinthemanufacturedof

polyesterandpolyamids(fibres)intextile

Conclusiononchemicalreaction;

Carboxilicacid+reactivemetal

carboxylatesalt+hydrogen

Carboxilicacid+base

carboxylatesalt+water

Carboxylateacid+metalcarbonate

carboxylatesalt+carbondioxide+

Water

Carboxilicacid+alcohol

ester+water

1.Learningtask2.9Summarizingpg75

[notesbook]

2.EffectivePractisepg75

1,2,3

[exercisebook]

ESTER

GeneralformulaCnH2n+1COOCmH2m+1

R :alkylgroupincarboxilicacid

R’ :alkylgroupinalcohol

O

║

CnH2n+1C—OH+CmH2m+1OH

(carboxilicacid)(alcohol)

O

║

CnH2n+1C—O—CmH2m+1+H2O

(ESTER)

Esterification

-Carboxilicacidreactswithalcoholtoproduce

esterandwater.

-Thefunctionalgroupofesteriscarboxilate

group.

-Concetratedsulphuricacidiscatalyst.

-Carboxilicacidlosses‘OH’and

-Alcohollosses‘H’

-Thebondthat‘breakup’will‘rejoin’again

CnH2n+1—C

O

O

CmH2m+1

Breakupandrejoin

Carboxilategroup,-COO-

Derivedfromcarboxilicacid

Derivedfromalcohol

NamingEster

-Nameofesterconsistsoftwoparts,thename

ofalcoholpartisgivenfirstandfollowedby

theacidpart.

Example:i.Ethanoicacid+methanol

methylethanoate+water

Chemicalequation:

CH3COOH+CH3OH→CH3COOCH3+H2O

HO

|║

H—C—C—OH

|

H

CH3COOH

(Etanoicacid)

H

|

H—C—OH

|

H

CH3OH

(Methanol)

+

HOH

|║|

H—C—C—O—C—H+H2O

||

HH

CH3COOCH3

(Methylethanoat)Water

Example:ii.Ethanoicacid+ethanol

ethylethanoate+water

Chemicalequation:

CH3COOH+CH3CH2OH→CH3COOCH2CH3+H2O

HO

|║

H—C—C—OH

|

H

Ethanoicacid

HH

||

H—C—C—OH

||

HH

Ethanol

+

HOHH

|║||

H—C—C—O—C—C—H+H2O

|||

HHH

ethyletanoatWater

Example:iii.Methanoicacid+Ethanol

ethylmethanoate+water

Chemicalequation:

HCOOH+CH3CH2OH→HCOOCH2CH3+H2O

O

║

H—C—OH

Methanoicacid

HH

||

H—C—C—OH

||

HH

Ethanol

+

OHH

║||

H—C—O—C—C—H+H2O

||

HH

EthylmetanoatAir

Q:Drawstructuralmoleculeof

i.Methylmetanoate

ii.Pentylpropanoate

iii.Propylethanoate

Solutions;i.Methylmetanoate

Methylmethanoate

H

|

H—C—OH

|

H

O

║

H—C—OH

Methanol

Methanoicacid

Breakupandrejoin

Fromalcohol

Fromcarboxilicacid

OH

║|

H—C—O—C—H+H2O

|

H

methylmetanoateAir

ii.Pentylpropanoate

Trynow

Prophylethanoate

HHH

|||

H—C—C—C—OH

|||

HHH

HO

|║

H—C—C—OH

|

H

Propanol

Ethanoicacid

Breakupandrejoin

Fromalcohol

Fromcarboxilicacid

HOHHH

|║|||

H—C—C—O—C—C—C—H+H2O

||||

HHHH

propylethanoateWater

Preparationofesterthroughreflux

XXXXXXXXXXXXXXX

Tisseltube

Liebigcondenser

Ethanol+

ethanoicacid+

concentratedsulphuricacid

Porcela