Alkohol dan Ether 2015

7/23/2019 Alkohol dan Ether 2015

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ALCOHOLS,

PHENOLSAND

ETHERSKimia Organik


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Bonding for oxygen atoms inorganic compounds

Oxygen is commonlyfound in two forms inorganic compounds:

Oxygen is group 6ANeeds to form two bonds

to get an octet.


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Structural caracteristics ofalcools

Alcools a!e te general formula:

"#O$

were %"& in!ol!es a saturated '#atom

(bound to ydrogens and)or otercarbons*.

+or example:


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,

Alcools- ters and poxides

/ Alcools contain a ydroxy group (O$* bonded to an sp0 ybridi1edcarbon.

2ntroduction3Structure and Bonding


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/ 5en an O$ group is bonded to a ring- te ring is numberedbeginning wit te O$ group.

/ Because te functional group is at '- te is usuallyomitted from te name. (O$ pada posisi #7 8iilangkan*

/9e ring is ten numbered in a clockwise or counterclockwisefasion to gi!e te next substituent te lowest number.

Figure 9.2xamples: Naming

cyclic alcools


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/ 'ommon names are often used for simple alcools. 9o assign a

common name:Name all te carbon atoms of te molecule as asingle alkyl group.

Add te word alcool- separating te words wit aspace.


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Structural caracteristics ofalcools

'ondensed structural formulas or line#anglestructures are commonly used for depictingalcools

#;ropanol

#Butanol

2


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Nomenclature for alcools

Name te '#atoms of a single alkyl groupas for alkanes.

Add te word %alcool& following a space

after te alkyl name.

'ommon names for alcools


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Nomenclature for alcools

+ind longest- continuous '#cain to wic te O$group (ydroxyl* is bound. Number te cain in away tat gi!es te O$ group te lowestnumbering.

Name and number oter substituents present.

9e name for te corresponding alkane cain(e.g. for a 6#' cain- exane* loses te %e& andpicks up %ol& (exanol*.

+or cyclic alcools- te O$ group is understood tobe attaced to '#.

2


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/ 'ompounds a!ing a ydroxy group on a sp=ybridi1ed carbon3enolsand penols3undergo di?erent reactions tan alcools.

/ tersa!e two alkyl groups bonded to an oxygen atom.


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=

/ poxides are eters a!ing te oxygen atom in a tree#membered ring.poxides are also called oxiranes.

/9e '3O3' bond angle for an epoxide must be 6@- a considerablede!iation from te tetraedral bond angle of @.4. 9us- epoxidesa!e angle strain- making tem more reacti!e tan oter eters.


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/9e oxygen atom in alcools- eters and epoxides is sp0 ybridi1ed.Alcools and eters a!e a bent sape like tat in $=O.

/9e bond angle around te O atom in an alcool or eter is similar tote tetraedral bond angle of @.4.

/ Because te O atom is muc more electronegati!e tan carbon orydrogen- te '3O and O3$ bonds are all polar.


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Alcools wit more tan oneO$ group

;olyydroxyl alcools possess moretan one O$ group.

Alcools wic possess two O$groups are called %diols& and tosewit tree O$ groups are called%triols&

Alkane name C diol- %triol&- etc.


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/ 'ompounds wit two ydroxy groups are called diols or glycols.

'ompounds wit tree ydroxy groups are called triolsand so fort.


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2somerism for alcools


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'ommonly encounteredalcools

DouE!e probably used a few of tefollowing alcools:

>etyl and etyl alcool

2sopropyl alcool

tylene glycol (-=#tane diol*

;ropylene glycol (-=#;ropane diol*

Flycerol (-=-0#;ropane triol*

' l t d


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Methanol ('$0O$* Gnds use as a sol!ent in

cemical reactions and in fuel for ig#performance combustion engines.

'an cause permanent blindness or deat inig amounts

Hapors are !ery dangerous as well

8rinking metanol is a no#no. 2t ismetaboli1ed to formaldeyde and formic acid

by te li!er (alcool deydrogenase*:


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tanol('$0'$=O$* is also metaboli1ed by te body- and

tis reaction produces acetaldeyde and acetic acid:

xcessi!e drinking leads to li!er cirrosis- pysiologicaladdiction- loss of memory. 8rinking during pregnancyposes risks for birt defects.

tanol is sometimes rendered undrinkable by te additionof small Iuantities of toxic substances (e.g. ben1ene*.

2ndustrially- etanol is syntesi1ed by ydration of etene.


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tanol

9oxic to umans

Acute poisoning kills se!eral undreda year (drinking contests*

Jong term poisioning

>ost serious drug problem in


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2sopropyl alcool is used in rubbing alcool(@ isopropyl alcool in $=O* and in

cosmetics.

"apid e!aporation

Antiseptic

>ore toxic tan etanol- but induces!omitting

2ngested- isopropyl alcool is metaboli1ed toacetone:

'ommonly encountered


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tylene glycoland propylene glycolare colorless

and odorless and !ery water#soluble.


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Fycerol is a tick liIuid tat is normally present inte body (it is a product of fat metabolism*.

Because of its aLnity for water- it is often addedto parmaceutical preparations suc as skinlotions and soap- and for sa!ing cream andglycerol suppositories.

;ysical properties of


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;ysical properties ofalcools

Alcools consist of:

a non#polar (alkane#like* cain

a polar ydroxyl group

9us- alcools migt be water#soluble- or not (depending

on te lengt of te carbon cain*. 5e already saw tat te boiling points of alkanes increase

wit increasing cain lengt. 9e same is true for alcools.

Alcools wit more tan one ydroxyl group (polyydroxyalcools* a!e iger boiling points tan monoydroxy

alcools. Boiling pointstane: -89oC>etanol: 65oCtanol: 78oC-=#tane diol: 197oC

Jondon forces

Jondon C $#bonding

Jondon C more$#bonding

Jondon C $#bonding


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9e water#solubility of alcools depends on telengt of te alkyl cain in te alcool.

>onoydroxy alcools a!ing cains longer tantree carbons are not !ery water#soluble.

;olyydroxy alcools are more soluble becausetey a!e more opportunities for ydrogen#bonding wit water.


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Alcools a!e igerboiling points tanalkanes of te same cainlengt (because tey

ydrogen bond to eacoterM te intermolecularforces for alkanes areonly Jondon forces*

Alcools of a gi!en cain

lengt are far more water#soluble tan alkanes.

"emember: $#bonding is te strongest intermolecular force.Jondon forces are weak by comparison.


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'lassiGcation of alcools

Alcools may be classiGed as o- =o- or 0o- by considering tenumber of carbons bound to the hydroxy-bearing carbon.

Altoug alcools are able to $#bond- teir ability to do so

becomes impaired by oter carbon atoms near te ydroxygroup. 9e more carbon groups tat are bound to teydroxy#bearing carbon- te more tey get in te way of $#

bonding (steric indrance*.


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=

/ Simple eters are usually assigned common names. 9o do so:Name bot alkyl groups bonded to te oxygen-arrange tese names alpabetically- and add te wordeter.

+or symmetrical eters- name te alkyl group and addte preGx %di#&.

Nomenclature of ters


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0@

/ >ore complex eters are named using te 2


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/ poxides can be named in tree di?erent ways3As epoxyalkanes-oxiranes- or alkene oxides.

/9o name an epoxide as an epoxyalkane- Grst name te alkane cain orring to wic te O atom is attaced- and use te preGx %epoxy& toname te epoxide as a substituent.


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0=

/ poxides bonded to a cain of carbon atoms can also be named asderi!ati!es of oxirane- te simplest epoxide a!ing two carbons and

one oxygen atom in a ring.

/9e oxirane ring is numbered to put te O atom at position one- andte Grst substituent at position two.

/ No number is used for a substituent in a monosubstituted oxirane.


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/ poxides are also named as alkene oxides- since tey are oftenprepared by adding an O atom to an alkene. 9o name an epoxide in tis

way:

>entally replace te epoxide oxygen wit a doublebond.

Name te alkene.

Add te word oxide.


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/ Alcools- eters and epoxides exibit dipole#dipole

interactions because tey a!e a bent structure wit twopolar bonds.

/ Alcools are capable of intermolecular ydrogen bonding.

9us- alcools are more polar tan eters and epoxides.

;ysical ;roperties

/ Steric factors a?ect ydrogen bonding.


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;reparation of Alcools- ters- and poxides

/ Alcools and eters are bot common products of nucleopilicsubstitution.

/9e preparation of eters by te metod sown in te last twoeIuations is called te 5illiamson eter syntesis.


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/ 2n teory- unsymmetrical eters can be syntesi1ed in two di?erentwaysM in practice- one pat is usually preferred.


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/ An alkoxide salt is needed to make an eter.

/ Alkoxides can be prepared from alcools by a BrPnsted#Jowry acid3

base reaction. +or example- sodium etoxide (NaO'$='$0* is preparedby treating etanol wit Na$.

/ Na$ is an especially good base for forming alkoxide because te by#product of te reaction- $=- is a gas tat Qust bubbles out of te reaction

mixture.


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/ Organic compounds tat contain bot a ydroxy group and a alogenatom on adQacent carbons are called aloydrins.

/ 2n aloydrins- an intramolecular !ersion of te 5illiamson etersyntesis can occur to form epoxides.


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;reparation of alcools. Alcools can be prepared by ydration of alkenes

(as we saw in 'apter#0*:

=. 9ey can also be prepared by te ydrogenationof '#O double bonds:

($ydrogenation of tis double bond is eIui!alent to a reduction in organic

' i l i f


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'emical reactions ofalcools

.'ombustion makes 'O=and $=O

=.8eydration (loss of water intramolecular* make an alkene

0.8eydration (loss of water intermolecular* makes an eter

,.Oxidation makes a carboxylic acid

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. Any organic molecule can undergo acombustion reaction. 2n combustionreactions in!ol!ing alcools- 'O=and

$=O are produced:

'$0O$ C O='O=C =$=O

'$0'$=O$ C O=='O=C 0$=O

Or- for =#;ropanol:

'ombustion reactions

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=. 2n an intramolecular alcool deydration- awater molecule is lost (eliminated* from asingle alcool molecule.

9e elimination in!ol!ed loss of te O$ group

and a $#atom from an adQacent '#atom(sometimes- tereEs more tan one of tese*

limination reactions

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'emical reactions ofalcoolslimination reactions

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In general- tese kinds of reactions(eliminations* proceed as follows:


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2f tere is more tan one adQacent carbonatom from wic loss of a $#atom canoccur- tere will be more tan one possiblealkene deydration product:


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Raitse!Es "ule (for alcool deydrations*: for caseswere more tan one alkene product migt beformed from an elimination reaction- te ydrogenatom tends to be remo!ed from te carbon tat

already possesses te fewest ydrogens.


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0.9e alcool deydration reaction (like allcemical reactions* is an eIuilibrium. Sinceit occurs troug elimination of an $=O

molecule- conditions tat fa!or $=O loss (dryconditions (concentrated $=SO,*- ig

temperatures* fa!or alkene formation.

On te oter and- if tis reaction were run

in dilute $=SO,- alcool formation would befa!ored.


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,. 5en lower temperatures are used tan tose tatyield alkenes- intermolecular loss of water tends tooccur (in!ol!ing two alcool molecules* to produceeters:

'ondensation reactions

8imetyl eter

A condensation reaction is a reaction in wic two molecules combine to fa larger molecule wile liberating a small molecule like water.

' i l ti f


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xample ,.0- pg. ,,: identify te alcoolneeded to produce eac of te following alcooldeydration products:

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Oxidation)reduction reactions in!ol!ing organiccompounds result in a cange in te number of $#atoms and)or te number of O#atoms bound tocarbons in te molecule:

Oxidations increase te number of '#O bondsand)or decrease te number of '#$ bonds in amolecule.

"eductions decrease te number of '#O bonds

and)or increase te number of '#$ bonds in amolecule.

Oxidation reactions

'emical reactions of


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;rimary and secondary alcools can be oxidi1ed by mildoxidi1ing agents to produce compounds wit '#O doublebonds (aldeydes- ketones- carboxylic acids*.

Oxidation reactions

No $ on O$#bearingcarbon to remo!e ere.

St t l t i ti f


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Structural caracteristics ofpenols

;enols are aromatic compounds tat bear a O$group.

9is is anoter %special case& compound as far as2


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Ben1enes tat are substituted wit botO$ and '$0groups are called cresols

(2


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+or diidroxy#ben1ene structures- te following2


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;ysical and cemical propertiesof penols

Alcools and penols are Tammable.

Alcools can be deydrated- but notpenols

oand =oalcools are oxidi1ed by mildoxidi1ing agents. 0oalcools and penolsdo not undergo oxidation in tese

conditions. Alcools and penols can undergo

alogenation were te O$ group isreplaced by a alogen.

;ysical and cemical


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;ysical and cemicalproperties of penols

;enols are weak acids in water.9ey undergo deprotonation- asdiscussed in '#@:

Occurrence and uses of


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Occurrence and uses ofpenols

an antiseptic disinfectants

antioxidants


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ters

8eri!ati!es of water

Bot ydrogen atoms are replaced

Naming Symmetrical

Name groups attaced and add eter


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;roperties

Uuite inert

Altoug react !iolently in te air

Jow boiling points3no ydrogenbonds

8ietyl eter

+orms a peroxide in air

+irst general anestetic


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Nomenclature for eters

ters are organic compounds in wic twosaturated carbon atoms are bound troug asingle oxygen atom.

xamples:

common names


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Nomenclature for eters

9e 2


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2somerism in eters

Because eters contain '- $- and O atoms- tepossibilities for isomers is greater tan forydrocarbons.

+or example- an eter a!ing two tree carboncains will a!e te following constitutionalisomers:


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2somerism in eters

Vand ten te following functional group isomers(eters a!e te same general formulas asalcools*.

+unctional group isomers: constitutional isomers tat contain di?erent functi

;ysical and cemical properties


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;ysical and cemical propertiesof eters

Boiling points and melting points are dictated byintermolecular forces. 'ompared wit alkanes ofsimilar molar mass- an eter will a!e a similarboiling point. 'ompared to an alcool of te

same molar mass- te eter will a!e a muclower boiling point.

Jondon forces

Jondon forces

Jondon forcesC

$#bonding

2ntermolecular force

;ysical and cemical


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;ysical and cemicalproperties of eters

ters are more water#soluble tan alkanes- becausewater molecules can $#bond wit tem.

An eter and an alcool of te same molar mass a!eabout te same solubility in water.

Some important cemical properties of eters: ters are hihl! "a##a$le. 9e b.p. of dietyl eter is 04o'

and eter !apor ignites readily.

ters react wit O=to form ydroperoxides and peroxides

(unstable compounds wic can explode*

Oterwise- eters react similar to alkanes in combustion andalogenation reactions.


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'yclic eters

'yclic eters are similar tocycloalkanes)cycloalkenes- but possess an O#atom as part of te ring.

'yclic organic compounds in wic one or more

carbon atoms of te ring a!e been replaced byatoms of oter elements are called eterocyclicorganic compounds.

"eaction of ters wit Strong Acid


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/2n order for eters to undergo substitution orelimination reactions- teir poor lea!ing group

must Grst be con!erted into a good lea!inggroup by reaction wit strong acids suc as$Br and $2. $Br and $2 are strong acids tatare also sources of good nucleopiles (BrW and2W respecti!ely*.

/5en eters react wit $Br or $2- bot '3Obonds are clea!ed and two alkyl alides are

formed as products.


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"eactions of poxides

/"ecall tat epoxides do not contain a goodlea!ing group.

/poxides do contain a strained tree#membered ring wit two polar bonds.

/Nucleopilic attack opens te strained tree#membered ring- making it a fa!orable processe!en wit a poor lea!ing group.


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Sulfur analogs of alcools

9iols a!e te general formula "#S$. 9is is likean alcool ("#O$*- and bot O and S are group 6elements (and tus possess similar cemistry*.

9e S$ group of te tiol is called a sulfydryl

group. Nomenclature: named similar to alcools- but te

&ol& part of te becomes &tiol&M also- te alkanepart of te name becomes retained:


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9e common naming system fortiols in!ol!es use of te term%mercaptan&


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2n terms of properties and cemicalreactions of tiols:

9ey generally a!e lower boiling points

tan alcools of similar structure (no $#bonding*

9ey stink

'emical reactions:

9iols are easily oxidi1ed to form disulGdes(important for protein cemistry*


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Sulfur analogs of eters

9ioeters are organic compounds in wic twosaturated carbon atoms are linked troug asingle sulfur atom.

9e common naming system for tioeters is

similar to tat for eters- wit te name %eter&being replaced by %sulGde&

2


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Sulfur analogs of eters

2n general- tioeters and tiols are morereacti!e tan teir eter and alcoolcounterparts.

'#S bonds are weaker tan '#O bonds +unctional group isomers are also a

possibility for sulfur compounds

Documents

Alkohol dan Ether 2015