Alcohols and Phenols

ALCOHOLS & PHENOLS An important portion of this corse is the reco!nition of or!anic chemistry fnctional !rops" #hese are parts of a molecle$ %ith %ith a specific strctre strctre that fnctions in a certain %ay" Not only are yo to learn to reco!nie the fnctional !rops (a listin! can 'e fond in yor tet'oo or on the 'ac co*er of this la'oratory manal)$ 't yo are also to learn the physical and chemical properties of each of the fnctional !rops stdied in the corse" #his la'oratory eercise %ill introdce yo to t%o of these fnctional !rops$ alcohols and phenols$ as %ell as some of their physical and chemical properties" Alcohols

Altho!h yo may 'e familiar %ith +alcohol, as a 'e*era!e$ the %ord actally represents an entire entire classificat classification ion of or!anic molecles molecles and not st st one s'stance" s'stance" Alcohols Alcohols contain contain the fnctional !rop attached to a satrated car'on" Notice that %e did not call call this −OH (hydroyl) fnctional the hydroide ion$ 'ecase this !rop does not act act as an ionic s'stance" Alcohols are classified into three cate!ories. primary (/0)$ secondary (20) and tertiary (10)" #his classi classific ficati ation on is 'ased 'ased on the nm'er nm'er of car'oncar'on-cont contain ainin! in! !rops !rops ( − for an alyl or an aromatic !rop) attached to the car'on 'earin! the hydroyl !rop" 3f the car'on 'earin! the −OH has one  − !rop$ the molecle is a primary alcohol" 3f t%o  − !rops are attached$ it is a secondary alcohol" 3f three  − !rops are attached$ the alcohol is tertiary" CH3 CH3 CH3 CH3

CH2

OH

CH3

CH

C

OH

OH CH3

ethanol (primary)

2-propanol (secondary)

2-methyl-2-propanol (tertiary)

3" Physi Physica call Prope Propert rtie iess of Alcoh Alcohol olss R

#he hydroyl hydroyl !rop present present in all alcohol alcoholss is a polar polar fncti fnctional onal !rop" !rop" #he polari polarity ty of this !rop !rop allo%s allo%s alcohols alcohols to form hydro!en hydro!en 'onds" Small Small chain alcohols alcohols are a'le to mi %ith %ater 'ecase of the hydro!en 'ondin! interactions that %ill occr 'et%een the hydroyl fnctional !rop and the %ater" 3f the -!rop of the alcohol 'ecomes too lar!e ho%e*er$ the sol'ility of the alcohol %ill decrease"

O H

. Hydrogen bonding . . O H

H

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Procedure:

/" Place Place /5 drops of each each alcoho alcoholl (ethan (ethanol$ ol$ /-'tanol /-'tanol$$ 2-'ta 2-'tanol nol$$ 2-meth 2-methyl yl-2-p -2-prop ropanol anol and /-octanol) into its o%n test t'e" Add /-2 ml ml of %ater to each t'e" ecord yor o'ser*ations on the data sheet" 2" Place another another /5 drops drops of each of the a'o*e a'o*e alcohols alcohols into its o%n o%n test test t'e" t'e" Add /-2 /-2 ml of dichloromethane" dichloromethane" ecord yor o'ser*ations on the data sheet" sheet"

66CA 66CA7# 7#3O 3ON6 N666

83CH 83CHLO LOO O9E 9E#H #HAN ANE E 3S :LA9 :LA99A 9A;L ;LE" E" " A?O38 ;EA#H3N@ ;EA#H3N@ :79ES" =O< 3N #HE HOO8 AS 97CH AS POSS3;LE" POSS3;LE" =EA SA:E#> @LASSES @LASSES 3N #HE LA;OA#O> A# ALL #39ES6

33" Chemica Chemicall Propert Properties ies of Alcoho Alcohols ls #he classification of an alcohol as primary$ secondary or tertiary (see a'o*e) affects the chemical properties of the alcohols" #his difference in chemical properties can 'e sed as a means of identi identific ficati ation" on" #he Lcas test test and the chromic chromic acid test are t%o common common methods methods sed sed to distin!ish amon! primary$ secondary and tertiary alcohols" A" Lca Lcass #es #est. t. #he Lcas rea!ent contains inc chloride and hydrochloric acid" =hen the Lcas rea!ent is allo%ed to react %ith an alcohol$ an alyl halide is formed" #his alyl halide %ill not 'e sol'le in %ater$ ths clodiness or a second layer of droplets %ill form if the test is positi*e" =ith this rea!ent$ tertiary alcohols react immediately$ secondary alcohols in 1 to /5 mintes$ and primary alcohols may tae an hor or lon!er$ or may ne*er react"

-OH



HCl

4nCl2

-Cl  (insol'le)

H2O

Procedure:

1" Place 2 mL mL of the Lcas Lcas rea!ent rea!ent in a test test t'e" t'e" Add B drops drops of ethanol ethanol"" Shae the the t'e to mi the materials and note the time reired for the mitre to 'ecome clody or to





66CA 66CA7# 7#3O 3ON6 N666

Hydr Hydroch ochlo lori ricc acid acid is *ery *ery corr corros osi* i*e" e" Any Any spil spilll shol shold d 'e imme immedi diat atel ely y flshed %ith %ater" =ear safety !lasses in the la'oratory at all times"

;" Chro Chromi micc Acid Acid #est #est.. Chromic acid (acidified dichromate$ an oidiin! a!ent) can also 'e sed to distin!ish 'et%een types of alcohols 'y oidiin! the alcohol" Primary alcohols are oidied to car'oylic acidsD secondary alcohols are oidied to etonesD and tertiary alcohols are not oidied" oidied" 8rin! 8rin! the oidation$ the oran!e-red oran!e-red color of the chromic acid chan!es to a 'le!reen soltion" O 

CH2

OH 

(prima (primary ry))

C OH  H2CrOB   Cr 2(SOB)1  (red-o (red-oran ran!e) !e) (car'o (car'oy ylic lic acid) acid) ('le('le-!re !reen) en)

OH 

CH

H2O

O 



(s (secondary)

H2CrOB  (red-oran!e)



C



(etone)



Cr 2(SOB)1  ('le-!reen)

H2O

OH 

C





H2CrOB



No eaction



(tertiary)

Procedure:

B" Place Place /5 drops drops of aceto acetone ne in a test test t'e t'e"" Add F drop dropss of ethano ethanoll and 2 drop dropss of chromic chromic acid to the t'e" Note and record the color of the soltion soltion on the data sheet" epeat this procedre for /-'tanol$ 2-'tanol$ and 2-methyl-2-propanol"





Phenols

Phenols are closely related to alcohols 'ecase of the presence of the hydroyl (−OH) !rop" 3n phenols$ ho%e*er$ the hydroyl !rop is directly 'onded to an aromatic !rop$ sch as 'enene" Phenol componds often ha*e crios 't sefl properties" Some are fond in preser*ati*es or medications. medications. #he chemistry of phenols is different than that of alcohols" Concentrated soltions of the compond phenol are ite toic and can case se*ere 'rns" In this experiment, we are using an aqueous solution of phenol.

66CA 66CA7# 7#3O 3ON6 N666

Pheno Phenoll is toi toicc and and %ill %ill cas casee 'rns 'rns to sin sin"" E*en E*en tho! tho!h h %e are are sin sin! ! an aeos soltion of phenol$ any contact shold 'e thoro!hly %ashed %ith lar!e antities of %ater" =ear safety !lasses at all times in in the la'oratory" eport all accidents to the instrctor" instrctor"

333" Physical Physical Properties Properties of Phenols Procedure:

F" Place Place /5 drops drops of phenol phenol solti soltion on into into a test t'e" t'e" Add /-2 /-2 ml of dichlo dichlorom rometh ethane ane"" ecord the o'ser*ations for sol'ility on the data sheet"

3?" Chemical Chemical Properties Properties of Phenols Phenols Phenols Phenols react differentl differently y than alcohols" #his is %hy they are !i*en their o%n fnctional fnctional !rop and are not technically technically Galcohols", Galcohols", =e %ill see this this difference difference in the chromic acid acid test and the ferric chloride test" A" Chro Chromi micc Acid Acid #est #est Phenols can 'e oidied %ith chromic acid$ 't they !i*e different types of prodcts than those formed from alcohols" #he chromic acid test is descri'ed a'o*e$ and the same reslts are epected for a positi*e test (a 'le-!reen soltion is formed)" Procedure:





Note Note..

3n the the inte intere rest st of time time$$ this this pheno phenoll eper eperim imen entt can can 'e carr carrie ied d ot at the the same same time as the alcohol eperiments" eperiments" Conslt instrctor if there is a pro'lem"

66CA 66CA7# 7#3O 3ON6 N666

Chro Chromi micc aci acid d is is *er *ery y cor corro rosi si*e *e"" Any Any spil spilll sho shol ld d 'e 'e imm immed edia iate tely ly flshed %ith %ater" =ear safety !lasses in the la'oratory at all times"

;" :err :erric ic Chlo Chlori ride de test test Addition of aeos ferric ferric chloride to a phenol creates a colored soltion" 8ependin! pon the strctre of the phenol$ the color can *ary from !reen to prple" Procedure:

I" Place 25 25 drops drops of the ferric ferric chloride chloride soltion soltion into a test t'e" Add F drops of phenol phenol soltion" Note and record any o'ser*ations on the data sheet" 3t is clear that some some of the procedres procedres %ill reire reire some time time to o'ser*e o'ser*e the reslts" reslts" #he %ell prepared stdent$ %ho has read the la'oratory eercise in ad*ance$ may realie that the phenol tests tests can 'e carried ot at the same same time some of the other other tests are are 'ein! done" #hese items items need not 'e tested seentially" seentially" As the instrctor if if yo need help"

UNKNOWN

O'tain an nno%n sample %hich is one of the follo%in!. /-'tanol$ 2-'tanol$ 2-methyl-2 propanol or aeos phenol" 7sin! the information and no%led!e !ained drin! this la'oratory$ and 'y tiliin! yor critical thinin! sills$ determine the identity of this nno%n" >o can assme that if a test %as not performed on a s'stance$ the s'stance did not react %ith the rea!ent" >or report mst inclde completion of the second data sheet %hich otlines the procedre for dete determ rmin inin in! ! the the nn nno% o%n" n" >o shold shold mae mae a hypot hypothe hesi siss and and then then desi! desi!n n or sele select ct an eperiment eperiment %hich %ill %ill spport or in*alidate in*alidate yor hypothesis" hypothesis" #o *erify the conclsion conclsion of yor nno%n nno%n$$ yo mst mst ha*e ha*e at least least three three eperi eperimen ments ts desi!n desi!ned ed to chec chec andJor andJor *erify *erify yor yor hypotheses" Please 'e 'rief 't clear and complete %ith yor hypotheses$ planned in*esti!ations$ in*esti!ations$





DATA SHEET I

8ate Alcohols & Phenols

Name Partners

Solubility:

ethanol

Eperiment 

Comp

/-'tanol 

letely Sol'le Sol'ility in H2O



Partia lly Sol'le



3nsol



Comp

letely Sol'le

2-methyl-2 propanol 

letely Sol'le









3nsol



3nsol



'le

Comp

/-octanol 

letely Sol'le



'le

Sol'ility in CH2Cl2

Comp

2-'tanol

'le

phenol

Comp letely Sol'le

Partia lly Sol'le 3nsol






3nsol

'le

'le







































3nsol



3nsol





3nsol





3nsol 'le

'le

'le

3nsol 'le

'le

3nsol 'le

Chemical Properties:

Eperiment

Lcas #est

Chromic Acid #est

ethanol

/-'tanol

2-'tanol

2-methyl2-propanol

phenol







8A#A SHEE# 33

8ateKKKKKKKKKKKKKKKKKK Alcohols & Phenols

NameKKKKKKKKKKKKKKKKKKKKKKKKK PartnerKKKKKKKKKKKKKKKKKKKKKKKK

UNKNOWN # KKKKKKKKKK  ;e sre to record the nm'er of yor nno%n here6

/"

A" Hypothesis. ;" Planned 3n*esti!ation. C" O'ser*ations (data). 8" Conclsion.

2"

A" Hypothesis. ;" Planned 3n*esti!ation. C" O'ser*ations (data). 8" Conclsion.

1"

A" Hypothesis. ;" Planned 3n*esti!ation. C" O'ser*ations (data).





EPO# SHEE# 8ateKKKKKKKKKKKKKKKKKK Alcohols & Phenols

NameKKKKKKKKKKKKKKKKKKKKKKKKK PartnerKKKKKKKKKKKKKKKKKKKKKKKK

Ans%er the follo%in! estions. /" 9y 7nno%n (KKKKKK) %as. (circle all that apply) /-;7#ANOL

2-;7#ANOL 2-;7#ANOL

2-9E#H>L-2-POPANOL 2-9E#H>L-2-POPANOL

PHENOL

2" Salicy Salicylic lic acid$ acid$ sho%n sho%n 'elo%$ 'elo%$ cold cold 'e ('t$ ('t$ it %asnMt) %asnMt) sed sed as an nno%n nno%n"" 8escri 8escri'e 'e %hat %hat yo %old %old seeJle seeJlearn arn as yo Ganalyed, Ganalyed, this s'stanc s'stancee if it %ere %ere yor yor nno%n nno%n in the follo%in!.

OH

Sol'ility in %ater.

O C

:eCl1 #est.

OH salicylic acid 1" =hat reslts reslts %old %old yo epect epect from from the reaction reaction of /-propano /-propanoll %ith each each of the follo%i follo%in! n! Lcas rea!ent.

Chromic acid rea!ent.

B" Alcohols Alcohols are more sol'le sol'le in in %ater %ater than than hydrocar hydrocar'ons 'ons are are in in %ater" %ater" =hy

Alcohols and Phenols

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