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CHEM%222%

Report%Sheet%

2018-2019%

Reduction*of*a*Ketone* %

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Solo!Experiment!1!–!Individual!Lab!Report! ! Last%Name:% First%Name:% TA%Name:% Lab%Partner(s):% Date%Lab%Performed:% Group:% Comments:%

Leave%any%comments%for%the%Grading%TA%here.% If%you%performed%your%lab%on%a%day%other%than%your% scheduled%day,%please%provide%details.%

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CHEM%222%

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2018-2019%

Objective*(3*marks):% %%%%%%%The$purpose$of$the$following$experiment$was$to$reduce$cyclohexanone$to$ cyclohexanol,$in$other$words,$the$reduction$of$a$ketone$to$an$alcohol,$with$sodium$ % borohydride$as$the$reducing$agent.$The$cyclohexanone$was$then$further$reduced$ through$the$process$of$liquid-liquid$extraction,$filtered$by$gravity$filtration,$and$ dried$with$anhydrous$Na2SO4$for$the$removal$of$DCM,$which$formed$the$layers$in$ the$separatory$funnel.$Lastly,$the$IR$spectrum$of$the$product$was$taken$to$identify$ the$functional$groups$that$supported$the$formation$of$cyclohexanol.% % Introduction*(3*marks):* %%%%%%%Oxidation-reduction$reactions$play$key$roles$when$it$comes$to$chemical$processes.$It$ involves$the$transferring$or$loss$of$electrons$between$species.$More$specifically$ reduction$results$in$the$gaining$of$electrons,$and$oxidation$is$the$loss$of$electrons.$Both$ type$of$reactions$are$especially$important$for$providing$energy.$In$this$experiment,$a$ ketone,$specifically$cyclohexanone,$was$converted$to$an$alcohol,$cyclohexanol,$with$ sodium$borohydrideone$as$the$reducing$agent.$Sodium$borohydride$was$more$desirable$ than$lithium$aluminum$hydride$as$it$is$less$reactive$and$can$be$used$more$safely.$The$ secondary$alcohol$was$obtained$from$a$nucleophilic$addition$reaction$to$the$carbonyl$ group$of$the$ketone.$One$of$the$hydrogens$from$sodium$borohydride$attacked$the$ carbonyl$group$and$protonation$occurred$after$water$was$added,$for$cyclohexanol,$the$ secondary$alcohol,$to$be$achieved.% * Reaction*Scheme*(3*marks):%

% % % % % Materials%

Mass% Volume% Density% MW% Molarity% Moles% Theoretical% (g)% (mL)% (g/mL)% (g/mol)% (mol/L)% (mol)% Yield%(g)% Cyclohexanone% 1.4% 1.5% 0.945% 98.15% 9.3% 0.014% 1.50% NaBH4% 0.2% -% -% 37.84% -% 0.0053% -% Methanol% 4.0% 5.0% 0.792% 32.04% 24% 0.120% -% NaOH%solution% 11% 5.0% 2.13% 40.00% 3.0% 0.015% -% % H2O% 4.0% 4.0% 1.00% 18.02% 55% 0.220% -% Cyclohexanol% 1.4% 1.5% 0.948% 100.16% 9.3% 0.014% 1.47% % 2% %

CHEM%222%

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2018-2019%

Procedure*(3*marks):* %%%%%%%A$round$bottom$flask$of$50.0$mL$was$obtained$and$a$stir$bar$was$added$into$the$flask.$ 5.0$mL$of$methanol$and$1.5$mL$of$cyclohexanone$was$measured$and$then$added$into$the$ flask.$The$mixture$was$placed$in$an$ice$bath$for$3$minutes.$During$its$time$in$the$ice$bath,$ 0.20$g$of$NaBH4$was$added$into$the$solution.$After$3$minutes,$the$round$bottom$flask$was$ removed$from$the$ice$bath,$placed$on$a$mantle$set$to$the$stir,$and$cooled$to$room$ temperature$for$10$minutes.$A$white$and$cloudy$solution$was$observed.$The$reaction$was$ neutralized$when$5.0$mL$of$a$3$M$aqueous$NaOH$was$added$into$the$round$bottom$flask,$ followed$by$4.0$mL$of$distilled$H2O.$$ $ $$$$$$$A$125$mL$separatory$funnel$was$placed$on$a$stand,$whereby$the$content$in$the$round$ bottom$flask$was$transferred.$5.0$mL$of$DCM$and$5.0$mL$of$saturated$NaCl$was$then$ added$to$the$separatory$funnel$for$liquid-liquid$extraction.$The$funnel$was$shaken$a$few$ times,$then$inverted$to$open$the$stopcock$and$vent.$This$step$was$repeated$until$the$ pressure$was$reduced$in$the$separatory$funnel.$After$the$organic$and$aqueous$layer$had$ distinguished$themselves,$the$organic$layer$was$collected$into$a$clean$50.0$mL$ Erlenmeyer$flask.$A$cloudy/milky$physical$property$was$observed$in$the$collected$ organic$solution.$5.0$mL$of$DCM$was$added$to$the$aqueous$layer$and$liquid-liquid$ extraction$was$performed$again$for$the$remaining$organic$layer$to$be$collected.$The$ bottom$layer$was$collected$into$the$Erlenmeyer$flask,$which$contained$the$previous$ organic$layer.$The$upper$aqueous$layer$was$transferred$into$a$second$clean$50.0$mL$ Erlenmeyer$flask.$A$few$scoops$of$anhydrous$Na2SO4$were$added$to$the$Erlenmeyer$flask,$ which$contained$the$organic$layer,$until$the$solution$was$cleared$and$Na2SO4$clumped$ together.$A$lot$of$water$was$observed$in$the$solution$as$many$scoops$of$anhydrous$ Na2SO4$were$added.$A$clean$50.0$mL$Erlenmeyer$flask$was$pre-weighed$with$a$scale.$The$ organic$solution$was$filtered$by$gravity$filtration$into$the$pre-weighed$Erlenmeyer$flask$ with$a$stemless$funnel$and$a$fluted$filter$paper.$After$filtration,$the$DCM$that$remained$in$ the$organic$flask$was$evaporated$with$low$heat$and$light$air.$DMC$needed$to$be$removed,$ as$it$was$not$the$final$product$required$for$the$reaction$and$it$must$be$isolated$to$obtain$ the$alcohol.$The$Erlenmeyer$flask,$which$contained$cyclohexanol,$was$weighed$on$a$scale.$ The$yield$of$the$reaction$was$calculated$and$the$IR$spectrum$was$taken$for$the$final$ product.% % Results*(9*marks):* % Table*1.%Yield%and%Physical%Properties%of%Cyclohexanol% % Cyclohexanol% Yield%(g)%

0.99%g%

Yield%(%)% Appearance%

68%% Clear/colourless%liquid%

Key%IR%Stretches%

O-H,%sp3%C-H,%C-O%

% Figures*(1*mark).%See!Figure!1!(IR!Spectrum)!following!the!Discussion!section.!% ! 3% %

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Discussion*(15*marks):* % 1. Suggest%one%chemical!reason%(specific%to%this%experiment)%which%could%result%in%a%yield%of% less%than%100%%of%the%desired%product.%In!addition,%if%your%yield%was%greater%than%100%,% explain%why%that%could%be.% One%of%the%chemical%reasons%which%can%result%in%a%percent%yield%less%than%100%,%is%the% excessive%addition%of%Na2SO4,%the%drying%agent,%into%the%collected%organic%layer.%In%this%case,% the%organic%layer%was%absorbed%by%Na2SO4%and%the%quantity%of%the%final%product,% cyclohexanol,%was%decreased.%If%DCM%was%not%completly%evaporated%from%the%collected% organic%layer,%a%yield%greater%than%100%%would%be%obtained,%as%the%final%product%contained% DCM%and%cyclohexanol.% % 2. Lithium%aluminum%hydride%would%also%reduce%cyclohexanone%to%cyclohexanol.%List%three% changes%that%would%have%to%be%made%to%the%procedure/conditions%to%accommodate%lithium% aluminum%hydride%instead%of%sodium%borohydride.% LiAlH4%and%NaBH4%are%both%possible%reducing%agents%to%convert%a%ketone%into%an%alcohol,% however,%they%both%contain%different%properties.%LiAlH4%reacts%more%spontaneously%when% encountering%water,%and%can%act%violently%with%methanol%and%NaOH%solution%from%the% experiment.%Hence,%if%it%were%to%be%used%in%the%experiment,%a%proper%reagent%must%be%used,% such%as%THF%or%Et2O,%which%are%Lewis%bases%used%to%dissolve%the%Li+%ion%from%LiAlH4.% Furthermore,%as%LiAlH4%is%an%exothermic%process,%which%may%react%violently%and% spontaneously%with%air,%an%ice%bath%must%be%used%for%the%entirety%of%the%lab%for%the%heat%to%be% absorbed%and%for%the%reaction%to%be%slowed%down.%Lastly,%LiAlH4%has%a%specific%property%where% it%may%cause%a%fire%when%in%contact%with%water,%hence%all%instruments%must%be%dried,%dealt% with%care,%and%kept%away%from%the%presence%of%water.% % 3. Why%was%this%reaction%performed%in%an%ice%bath?% This%reaction%needed%to%be%performed%in%an%ice%bath%as%it%was%exothermic.%At%room% temperature,%sodium%borohydride%would%react%violently%and%at%a%fast%pace%with%water,%hence,% the%heat%can%be%absorbed%with%ice%and%the%reaction%would%be%slowed%down%for%cyclohexanone% to%be%reduced.% % 4. Analyze%your%IR%spectrum.%Explain%how%your%IR%spectrum%supports%the%formation%of%the% desired%product,%cyclohexanol.% The%IR%spectrum%supports%the%formation%of%cyclohexanol,%as%there%was%a%broad%peak%at% 3349.49%cm-1,%which%corresponded%to%the%presence%of%an%O-H%group%in%the%cyclohexanol.%The% strong%peak%at%2929.68%cm-1%showed%the%sp3%C-H%bonds%that%matched%with%cyclohexanol.% Furthermore,%the%strong%peak%at%1063.68%cm-1%correlated%with%the%C-O%bond%of%the% cyclohexanol.%There%was%no%peak%around%1630%cm-1–%1780%cm-1,%which%indicated%that%there% was%no%carbonyl%group%present%in%the%compound.% % %

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5. Draw%a%detailed%mechanism%for%the%reduction%of%cyclohexanone%to%cyclohexanol%using% sodium%borohydride%as%the%reducing%agent.%

% % End*of*Counted*Page*Limit*(5*Pages)* % Figure*1.%IR%Spectrum%of%Cyclohexanol% %

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* * References:* Cyclohexanone.$https://www.sciencedirect.com/topics/neuroscience/cyclohexanone$ (accessed$Sep$16,$2019).$ $ Libretexts.$Oxidation-Reduction$Reactions.$ https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_(A nalytical_Chemistry)/Electrochemistry/Redox_Chemistry/OxidationReduction_Reactions#targetText=An$oxidation-reduction$(redox),gaining$or$losing$an$ electron.$(accessed$Sep$16,$2019).$ $ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Cyclohexanol,$ CID=7966,$https://pubchem.ncbi.nlm.nih.gov/compound/Cyclohexanol$(accessed$on$Sept.$ 16,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Cyclohexanone,$ CID=7967,$https://pubchem.ncbi.nlm.nih.gov/compound/Cyclohexanone$(accessed$on$ Sept.$16,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Dichloromethane,$ CID=6344,$https://pubchem.ncbi.nlm.nih.gov/compound/Dichloromethane$(accessed$on$ Sept.$18,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Methanol,$CID=887,$ https://pubchem.ncbi.nlm.nih.gov/compound/Methanol$(accessed$on$Sept.$16,$2019)$ $ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Sodium$borohydride,$ CID=4311764,$https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-borohydride$ (accessed$on$Sept.$16,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Sodium$chloride,$ CID=5234,$https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-chloride$(accessed$on$ Sept.$18,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Sodium$hydroxide,$ CID=14798,$https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-hydroxide$(accessed$ on$Sept.$16,$2019)$ $ National$Center$for$Biotechnology$Information.$PubChem$Database.$Sodium$sulfate,$ CID=24436,$https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-sulfate$(accessed$on$ Sept.$18,$2019)$ $ 6% %

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Pham,$L.$B.$Study$Guide:$How$are$Photosynthesis$and$Cellular$Respiration$Related$to$Each$ Other?$https://www.brighthubeducation.com/science-homework-help/104248-plantphotosynthesis-and-cellular-respiration/#targetText=Therefore,$glucose$is$oxidized,$ while,to$a$carbon-based$molecule.$(accessed$Sep$16,$2019).$ $ Reduction$of$Aldehydes$and$Ketones$using$NaBH4$or$LiAlH4.$$ https://home.cc.umanitoba.ca/$(accessed$Sep$16,$2019).$ $ Sodium$Boronhydride$Reduction$of$Cyclohexanone.$ https://www.scribd.com/doc/151509986/Sodium-Boronhydride-Reduction-ofCyclohexanone$(accessed$Sep$16,$2019).% %

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