Exp3 Adn Orga

EXPERIMENT 3: OXIDATION OXIDATION OF CYCLOHEXANOL WITH PCC ON A SILICA GEL SUBSTRATE

OBJECTIVE •

To investigate the oxidation of cyclohexanol to cyclohexanone with PCC on a

•

silica gel substrate To investigate test of TLC To determine the IR spectrum of cyclohexanone

•

INTRODUCTION

Oxidation reactions of alcohols greatly increase the synthetic usefulness of these compounds. Only primary and secondary alcohols can be easily easily oxidied with the former converted to aldehydes or carboxylic acids and the latter to the corresponding !etones. The strength and selectivity of oxidiing agents varies widely" the use of oxochromium#I$% amine reagents is fundamental for a number of organic oxidative transformations. Pyridinium chlorochromate #PCC% is the most commonly used of these reagents" due to its availability" stability stability and versatility. Oxidation with PCC generally  proceeds through a simple" one step reaction &

EQUIPMENTS AND INSTRUMENTS

'. Pestle and mortar  (. )agnetic stirrer  *. Rotatory evaporator  +. IR 

MATERIALS

• • • • • • • • • • •

Cyclohexanol #,- '.'/% # .01 g2ml% .' g #'. mmol% Pyridinium chlorochromate #,- ('1.1/% .+* g #(. mmol% 3ilica gel #(* 4 + mesh% .+* g #for synthesis% 5ichloromethane Celite 3aturated 6aCl 7nhydrous 6a(3O+ 8thyl acetate Petroleum ether 3ilica gel #*9 : mesh% for filtering 3ilica gel #(*9 + mesh% for column chromatograpy

PROCEDURE

'. PCC and silica gel #(*o;+oo mesh was combined and grind with a pestle and mortar and a light orange powder was formed. (. The powder was added to (1ml round bottom flas! along with /ml dichloromethane. *. Then the cyclohexanol was added and stirred for (o;*o minutes. +. The solution was tested with TLC for every five minutes. 1. 7fter the reaction was completed" the reaction solution was diluted with 'oml of ether and the solution was filtered through a pipet containing a cotton plug" 'cm Celite" *cm silica gel #*1;:o mesh. /. The solution was extracted with (x1ml of water and saturated 6aCl solution. :. The solution was dried over anhydrous 6a(3O+ and the solvent was evaporated under vacuum. <. The crude product was purified using column chromatography #ethyl=acetate petroleum ether as the solvent system. 0. TLC was performed to identify the suitable solvent s ystem.

DATA AND RESULT Cyclo!"#$o$! S%!c&'#

7ssign 7 >

3hift #ppm% (.*1 (.: to '.11

CALCULATION C/?''O? #cyclohexanol% @ C/?'O #cyclohexanone% .' g C/?''O? x x x

'' molC  molC  0
)ass of C/?'O ; .0
R f  ; 1 minute ; ; .( ' minute

dis tan cetravelby sub tan ce dis tan cedtravelb ysolventfr ont  '. <.*

; ; .*/

*. <.*

'1 minute ; ; .((

'.< <.*

( minute ; ; .'0

'./ <.*

 (1 minute ; ; .*'

(./ <.*

* minute ; ; .(0

(.+ <.*

DISCUSSION

This experiment is run to produce cyclohexanone from cyclohexanol using the method of oxidation with PCC on a silica gel substrate. Anfortunately" the experiment was failed due to certain errors occurred during the experiment. The final product of cyclohexanone is not been obtained. Only the result for testing with TLC is obtained as it has been test at the beginning of the experiment after the cyclohexanol react with PCC. The result of TLC has been reported on calculation part. The TLC test should be conducted by using two solvent to compare with each other and to determine the suitable solvent. ?owever" in this experiment it was been conducted by using only one solvent which is ethyl acetate and the comparison cannot be held.

The final product of the experiment is not been obtained due to some errors. The error might come at the beginning of the experiment which is when the process of transferred the light orange powder from the mortar into anoth er container. 3tudents not ta!e into account the remaining powder that are stic! on the mortar which is it may affect the yield of the final product. 6ext" the using of cotton wool in the pipette is too much and made the solution been absorbed by the cotton wool result in decreasing the volume of the  product. The process to remove the solvent using rotatory evaporator showed the final  product is not been transferred to the other round bottom flas! proved the experiment was failed.

The literature melting point of cyclohexanone is 9+:oC in range. In IR spectrum" C;O functional group for !etone supposed to have IR absorption at range of '/<9':1 cm9'. 7romatic hydrocarbons show absorptions in the regions '/9'1<1 cm9' and '19'+ cm9' due to carbon9carbon stretching vibrations in the aromatic ring.

CONCLUSION The experiment failed. Cyclohexanone is not obtained from the experiment.

PROBLEMS

'. -ould the final product been any if you had used strong oxidiing agents such as chromic acidB Y!+, T! (-$#l %'o.*c& #+ .-((!'!$& /!$ *+!. # +&'o$0!' o"-.-1-$0 #0!$&,

-hat would your products have been if you had been oxidiing the following compound with 7. PCC Fo' +!co$.#'y #lcool co$)!'&!. &o 2!&o$!+ /-l! (o' %'-4#'y #lcool co$)!'& &o #l.!y.!,

>. b.chromic acidB Fo' +!co$.#'y #lcool co$)!'&!. &o 2!&o$!+ /-l! (o' %'-4#'y #lcool

co$)!'& &o c#'5o"yl-c #c-.+,

(. iven that PCC is only sparingly soluble in C?(Cl( while cyclohexanol is miscible in C?(Cl(" suggest a reason for the importance of grinding the PCC and silica gel to form  powder. T! c'o4-*4 5y%'o.*c& .!%o+-&+ /-& %y'-.-$! #+ # +&-c2y 5l#c2 &#' /-c c#$ co4%l!&! /o'2*%, A..-&-o$ o( #$ -$!'& #.+o'5!$& &#& -+ +-l-c# 0!l &o #llo/+ &! +&-c2y 5y%'o.*c& &o #5+o'5 &o &! +*'(#c! #$. 4#2!+ /o'2*% !#+-!',

REFERENCES '. http&22www.nvcc.edu2alexandria2stb2chm2(+/2+/Doxidation.pdf  (. T.-.raham 3olomons and Craig >. ,ryhle #(''%. Organic chemistry #' th ed.%. Eohn -iley F 3ons" I6C. /0' pp.