SUBLIMATION Pamela Estrada, Estrada, Carlo Falconi, Shina Go, Joana Gozon, Monica Hamtig, and Caitlin Hao. Group 4 2F Medical Technology Technology Organic Chemitry !a"oratory
ABSTRACT Thi e#periment $a per%ormed o a to puri%y "enzoic acid uing u"limation, to determine and compare the melting point o% the product $ith a tandard, and to "e a"le to calculate the percentage reco&ery. 'n e&aporating dih %illed $ith (.))g o% impure "enzoic acid that i co&ere co&ered d $ith a per%or per%orate ated d paper paper and an in&ert in&erted ed $atch gla $a heated heated uing a hot plate, plate, and cooled cooled $ith $ith a $et tiue paper imultaneouly %or *)+*( minute. '%ter thi part o% the procedure, the et+up $a allo$ed to cool. 'll the u"limate that $ere adhering to the $atch gla and per%orated paper $ere collected and $eighed to "e a"le to compute %or the percentage reco&ery. The u"limate $a then grounded into a %ine po$der and $a compared $ith a pure "enzoic acid "y determining the melting point range through the ue o% an oil "ath o a to ditinguih the purity o% the product.
INTRODUCTION enzoic enzoic 'cid i a $hite, $hite, crytallin crytalline e organic organic compound that "elong to the the %amily o% car"o#ylic acid-*. /t i lightly olu"le in $ater and ha a melting point o% *22 degree Celiu-2. Su"limation i the direct &aporization o% a olid "y hea heatin ting g $it $ithou houtt pa pain ing g thr throug ough h the li0 li0uid uid tate-1. /n order to puri%y the impure "enzoic acid, the proce o% u"limation $a ued in thi e#periment e#per iment.. The impuritie impuritie in the "enzo "enzoic ic acid contain amino compound that can "e %ound at a greater limit and mut "e taen a$ay "ecaue o% pheny phe nyll an and d "en "enzyl zyl com compou pound nd tha thatt e#t e#trem remely ely a%%ect the product o% the reaction. Thi proce occur $hen the &apor preure o% the u"tance i greater than that o% the atmopheric preure at the melting point. The puri%ic pur i%icati ation on pro proce ce in& in&ol& ol&ed ed in u" u"lim limati ation on i more mor e app applic lica"l a"le e %or imp impuri uritie tie $it $ith h lo$ &a &apor por preure or non+&olatile than pure u"tance or compound-4. The melting point o% an organic compound i one o% e&eral phyical propertie "y $hich it i iden id enti ti%i %ied ed,, o on one e $a $ay y to te tet t th the e pu puri rity ty o% a u"tanc u" tance e i "y determ determining ining it melting point. ' pure u"tance generally ha a melting range o% one one or t$o t$o degre egree e.. Thi Thi i the the di%% di%%er eren ence ce "et$ee "et$een n the temper temperatu ature re at $hich $hich the ampl ample e tart to melt and the temperature at $hich the ample mple com complet pletel ely y melte elted. d. The The ample mple33 impu impuri riti tie e tend tend to depr depre e and and "roa "roade den n the the melting range o the puri%ied ample hould ha&e a high higher er and and mal malle lerr melt meltin ing g rang range e than than the the original, impure ample-(. The o"ecti&e o% thi e#periment are5 6*7 To puri puri%y %y the impure impure "enzoic "enzoic acid acid through through u"limation. 627 To calcula calculate te the percent percentage age reco&e reco&ery ry o% the "enzoic acid a%ter u"limation. 617 To id iden enti ti%y %y th the e me melt ltin ing g po poin int t o% th the e u"l u "lim imat ate e an and d th the e pu pure re "e "enz nzoi oic c ac acid id through the ue o% an oil "ath.
EXPERIMENTAL A. Compoun Compounds ds teste tested d (or (or Sample Samples s used used
'$&ure ". Stru!tural 'ormula o Ben)o$! A!$d
The teted in
compound thi e#periment i only "enzoic acid "ut the group made ue o% it pure and impure %orm. The pure "enzoic acid $a the tandard $hile the impure "enzoic acid $a e#perimented on. enzoic acid i a $hite, crytalline organic compound-*, $hich ha a melting point o% *228C and ha a "oiling point o% 2498C at :;) mmHg or * atm. /t molecular %ormula i C :H;O2 and and it ha ha a +COO +COOH H %unc %uncti tion onal al grou group, p, mai maing ng it a car"o#ylic acid-;. B. Pro!edu !edure re ". Su#l$m #l$ma at$on $on To tart, (.))g o% impure "enzoic acid $a placed in an e&apor e&aporati ating ng dih, dih, and co&ered co&ered $ith a per%or per%orate ated d "ond "ond paper and an in&erted $atch gla. 'll opening $ere ecured $ith maing tape o a not to allo$ the &apor to ecape ecape %rom the et+up. et+up. Thi et+up et+up $a $a then heated heated uing a hot plate %or *)+*( minute until mot o% the ample $ere &aporized, a the center top o% the et+up $a cooled $ith a $et tiue paper that i ept moit $ith $ater. '%ter heating, the et+up $a allo$ed to cool, and the u"limate, in the %orm o% crytal, adhering to the ur% ur%ac ace e o% the the $atc $atch h gla gla and and paper paper $a $a care% care%ul ully ly collected and $eighed. The $eight o% the u"limate and the the $eigh $eightt o% the amp ample le $ere $ere ued ued to calcu calcula late te the the percentage reco&ery. %. Melt$ Melt$n& n& Po$n Po$ntt Deter Determ$n m$nat at$on $on To determine the melting point o% the product, the u"limate $a %irt pul&erized into a %ine po$der, and then placed in a capillary tu"e that i ealed on one end. The u"limate $a then paced at the "ottom o% the capillary
tu"e "y repetiti&ely dropping the cloed end o% the capillary tu"e through a gla tu"ing. Thi $a alo done $ith a pure "enzoic acid to ue a a tandard %or comparion $ith the product. The amount o% the u"limate and the tandard $ere o% the ame height in the capillary tu"e, auming "oth are $ell+paced and properly la"eled. Then, "oth $ere aligned $ith and attached to the mercury "ul" o% the thermometer. Thi et+up $a then immered in an oil "ath and heated. The initial temperature at $hich the u"limate and the tandard tart to melt and the %inal temperature at $hich the u"limate and the tandard completely melted $ere recorded.
Thermometer
Oil ath
Capillary tu"e ?itilled $ater to eep the tiue paper moit
Ga Source
unen urner >et tiue paper o&er the $atch gla
=&aporating dih $ith impure "enzoic acid co&ered $ith per%orated paper and in&erted $atch gla
*. Computat$ons '%ter the u"limate $a $eighed, computation $ere done. The percentage reco&ery o% the "enzoic acid $a then calculated uing the %ormula "elo$.
Hot
w yield benzoic acid w
=
w yield benzoic acid w
=
w yield benzoic acid w
=
weight of sublimate × 100 weight of sample 3.28 grams 5.00 grams
× 100
65.6
'lo, the initial temperature at $hich the %irt crytal tarted to melt, and the %inal temperature at $hich all the crytal completely melted $ere recorded. The di%%erence "et$een the %inal and initial temperature determine the melting point range and the purity o% the u"tance. Melting point range5
Melting point range =final temp− initialtemp
M . P .range of .
126 degC −124 degC
=
M . P .range of ¿ 2 degC
M . P .range of std .
125 degC −124 degC
=
M . P .range of ¿ 1 degC
RESULTS AND DISCUSSIONS The $eight o% the u"limate 6i.e. "enzoic acid7 and the $atch gla $ere meaured in order to determine the $eight o% the product. Thi data $a ued to calculate the percentage reco&ery $ith re%erence to the (.))+gram impure "enzoic acid ample. The $eight o% the $atch gla and the u"limate i ((.@:g $hile the $eight o% the $atch gla alone i (2.49g, o the $eight o% the product i 1.2@g. The percentage reco&ery o% the "enzoic acid u"limate $a calculated "y uing the $eight o% the u"limate di&ided "y the $eight o% the ample, then the 0uotient i multiplied "y *)). The computation ho$ that there i a ;(.;A reco&ery o% the "enzoic acid in the impure ample. Ta#le ". ?ata o% ample ued and calculated percentage reco&ery o% "enzoic acid u"limate Data determ$ned +e$&,t o t,e $mpure #en)o$! a!$d +e$&,t o t,e -at!, &lass and su#l$mate +e$&,t o -at!, &lass +e$&,t o su#l$mate Per!enta&e re!oer/
(.)) gram ((.@: gram (2.49 gram 1.2@ gram ;(.;A
'ide %rom $eighing and calculating the percentage reco&ery o% the "enzoic acid, the initial and %inal temperature o% the u"limate and the tandard at $hich they tarted to melt and completely melted $ere recorded o a to compare the purity o% "oth compound. oth compound tarted to melt at *24 oC. The tandard $a the %irt one to completely melt at *2(oC, and the u"limate completely melted ne#t at *2;oC. Thu, the melting range o% the tandard i *oC and the u"limate i 2oC. Ta#le %. Temperature and Melting
Su#l$mate Standard
In$t$al Temp *24oC *24oC
'$nal Temp *2;oC *2(oC
Melt$n& pt. ran&e 2oC *oC
The ey compound in thi e#periment i "enzoic acid. The "enzoic acid $a e#tracted %rom it impuritie uing the proce o% u"limation, a puri%ication techni0ue. /n the e#periment, the e&aporating dih %illed $ith impure "enzoic acid $a ealed to ecure the &apor o% the "enzoic acid that $ill cone0uently olidi%y $hen the center top i cooled. Thi techni0ue preented a relati&ely high percentage
reco&ery, conidering there are impuritie in the ample. The collected u"limate %ormed crytal and $ere pul&erized into a %ine po$der o a to %it in a capillary tu"e. The pure "enzoic acid $a alo pul&erized and placed in another capillary tu"e to ue a a comparion $ith the "enzoic acid u"limate. oth capillary tu"e $ere attached to the mercury "ul" tip o% the thermometer and the initial and the %inal temperature at $hich each o% the compound tarted and ended melting, repecti&ely, $ere recorded. Since a pure u"tance ha a melting range o% only * or 2 degree Celiu, the u"limate that $a collected can "e conidered a nearly a pure a the tandard. Sour!es0 -1 Helmentine, '. 62)*(7 Betrie&ed *)*)*( http5chemitry.a"out.comodchemitry gloaryau"limationde%.htm -4 Torre, <., D Criotomo, '. 62)*47. Laboratory Manual in Organic Chemistry: Revised Edition 6p. 1:+197. CD= . 62)*)7. CRC Handbook of Chemistry and Physics 69*t ed. ed., pp. 1+17. oca Baton, F!5 CBC
