Classification Tests for Organic Halides
Arnau, C. L., Capunitan, V. N., Cerezo, O. U. , Claudio, E. C., Co, M. A., Cortes, M. V. 2D-PH, Group 2, Department of Pharma!, "ault! of Pharma!, #ni$ersit! of %anto &omas Espa'a (oule$ard, )*)+ Manila, Philippines
Abstract rani halides are orani ompounds in hih one or more h!droen atoms ha$e /een su/stituted /! a haloen atom. Most of these ompounds are s!ntheti and flame retardant. 0n this e1periment, e1periment, different different tests ere made to differenti differentiate ate primar! primar!,, seondar! seondar!,, and tertiar! tertiar! orani halides /ased on their %N ati$it! and to mae a distintion /eteen their %N) and %N2 mehanisms. %ample ompounds of n-/ut!l hloride, se-/ut!l hloride, tert-/ut!l hloride and hloro/en3ene ere su/4eted throuh the (eilstein test, %N) 5eati$it! &est 6aloholi AN78 and %N2 5eati$it! &est 6Na0 in aetone8. All ompound samples produed a positi$e result ith (eilstein test /! impartin a ree flame, affirmin the presene of hlorine. 0n %N) 5eati$it! test the ompounds ere made to reat ith 29 ethanoli AN7 to o/ser$e %N) 5eati$it!, all samples produed a hite preipitate ith $ar!in times of formation here tert-/ut!l hloride e1hi/ited the fastest and n-/ut!l hloride as the sloest. Chloro/en3ene as o/ser$ed to e1hi/it no reation in the %N) 5eati$it! test. :hile in the %N2 reati$it! test usin Na0 in Aetone as the reaent, it as o/ser$ed that all ha$e samples e1hi/ited the formation of a hite preipitate e1ept for hloro/en3ene; hloro/en3ene; hereas hereas n-/ut!l n-/ut!l hloride hloride e1hi/ited the fastest fastest time of formation formation and tert-/ut!l hloride as the sloest.
Introduction In the labor laborator atory y and in indust industry ry,, alkyl halides are used as solvents for relatively non-polar compounds, and they are used as the starting materials for the synthesis of many compou pounds. Alkyl halides are are classied as primary (1o), seco second ndar ary y (o), or tertiary (! o) according to the number of carbon atoms directly bon bonded to the carbon bearing halogen. "omp "ompou ound nds s in #hic #hich h a halo haloge gen n atom is bonded to a sp-hybridi$ed carbon are called vinylic halides or phenyl phenyl halide halides. s. %inyl %inylic ic halide halide is a general term that refers to a
comp compou ound nd in #hic #hich h a halo haloge gen n is attached to a carbon atom that is also forming a doub ouble bond to another carbon atom. &henyl halides are compounds in #hich a halogen is attached to a ben$ene ring ring.. &h &hen enyl yl hali halide des s belo belong ng to a larger larger group group of compoun compounds ds called called aryl aryl halide halides. s. 'ogethe ogetherr #ith #ith alkyl alkyl halides, these compounds comprise a larger group of compounds kno#n simply as organi organic c halide halides s or organo organohal haloge ogen n compounds. 1 *rganic halides are organic compoun compounds ds contai containin ning g a haloge halogen n atom atom bond bonded ed to a carb carbon on atom atom..
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'he said halogen atom can either be chlori chlorine, ne, +uorin +uorine, e, bromi bromine, ne, or iodine. 'hese compounds are are consid consider ered ed to be +ame +ame retar retardan dantt and and most most of them them are are sy synt nthe heti tic. c. 'he halogen atom of an alkyl halide is attached to a sp!-hybridi$ed carbon. 'he arrangement of groups around the carbon atom, therefore, is gener generall ally y tetrah tetrahedr edral. al. ecause ecause halogen atoms are more electr electrone onegat gative ive than than carbon carbon,, the carb arbon-halogen bond of alkyl halides is polari$ed. alogen atom si$e increases as #e go do#n the peri period odic ic tabl table e #her #herea eas s +uor +uorin ine e Methodology
Samples &he samples used in the e1periment e1periment ere n /ut!l hloride, sec-/ut!l sec-/ut!l hloride, tert -/ut!l -/ut!l hloride and hloro/en3ene. Reagents &he reaents used in the e1periment ere 29 ethan ethanol oli i AN N7 and )+9 Na0 in anh!drous aetone. Beilstein Test: Test: Copper Halide Test Test &he test as onduted /! preparin one opper ire for eah sample to /e used. n one end of eah opper ire a small loop as made. &he loop as then heated diretl! in the the o1id o1idi3i i3in n 3one 3one of a non-l non-lum umin inous ous flame enerated /! a (unsen /urner. 0t as ontin ontinuou uousl! sl! heated heated until until the reen reen olor olor
atoms are the smallest and iodine atoms atoms the larges largest. t. "onse "onseuen uently tly,, the the carb carbon on-h -hal alog ogen en bond bond leng length th increases and carbon-halogen bond strength decreases as #e go do#n the periodic table. 'he ob/ectives of this e0periment e0periment are are (1) (1) to di2e di2errenti entiate ate prim primar ary, y, seco second ndar ary, y, and and tert tertia iary ry orga organi nic c halides based on their 34 reactivity, () () and to di2e di2errenti entiat ate e bet# bet#ee een n 341 an d 34 as reactive mechanisms #ith organic halides.
until the o1ide adhered to the loop. &he loop as as then then then then ool ooled ed sli sliht htl! l! and and as as dipped into the li
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sil$er sil$er halide halide preip preipita itate te to form form as then then reorded. &he olor of the preipitate as also reorded. % N2 5ea 5eati ti$i $it! t!== 5ea 5eati tion on ith ith %odi %odium um 0odide in Aetone 6)+9 Na0 in anh!drous aetone8
% N) 5eati 5eati$it! $it!== 5eati 5eation on ith ith Aloho Aloholi li %il$er Nitrate 629 ethanoli AN78 &he test as onduted /! plain 2* drops of 29 ethanoli sil$er nitrate in eah of the four four test test tu/es tu/es 6&a 6&ain in into into onsid onsidera eratio tion n that the solution of the reaent should not /e tur/ tur/id id hen hen used used8. 8. + drop dropss of n-/u n-/ut! t!ll hlo hlori ride de,, sese-/u /ut! t!ll hlor hlorid ide, e, tert tert-/ -/ut ut!l !l hloride and hloro/en3ene ere then added to their respeti$e test tu/es. &he test tu/es ere then shaen and the time it too for a
Results and Discussions
Beilstein Test Test (eilstein &est is a
&he test as onduted /! plain 2 drops of )+9 Na0 in anh!drous anh!drous aetone in eah of the four dr! test tu/es /es 6&ain into onsideration that the solution of the reaent should not /e tur/id hen used8. + drops of of n-/ut!l hloride, se-/ut!l hloride, tert /ut!l hloride and hloro/en3ene ere then adde added d to thei theirr resp respe eti ti$e $e test test tu/e tu/es. s. &he &he ontents of eah test tu/e ere then mi1ed and the time it too to form a preipitate as then reorded. &he olor of the preipitate as also reorded.
for identif!in the presene of a haloen, /ut does not positi$el! differentiate /eteen Cl, (r and 0. Heatin the opper ire /efore the test test is arri arried ed out remo remo$es $es the the trae traess of impurities hih ma! affet the result of the test.>7?
&a/le 2.) (eilstein &est 5esults Organic Sample n!"utyl chloride sec!"utyl chloride tert!"utyl chloride chloro"enzene
eilstein Test reen flame reen flame reen flame reen flame
&a/le 2.) shos the result of the said test here all of the samples imparted a reen flame lame.. &he pres presen ene e of a ree reen n flame lame
CuB2 is $olatile and imparts a /lue-reen flame. &he /lue-reen olor is due to the emis emissi sion on of lih lihtt from from e1it e1ited ed stat states es of oppe opperr halid halidee that that has has $apo $apori ri3e 3ed d in the the /urner flame. >?
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%il$er nitrate solution an /e used to find out hi hih h halo haloe en n is pres presen entt in a susp suspe ete ted d haloenoalane. &he most effeti$e a! is to do a su/stitution reation hih turns the haloen into a halide ion, and then to test for that ion ith sil$er nitrate solution. >+?
%gCl %gr
Doin the reation &he haloenoalane is armed ith some sodium h!dro1ide solution in a mi1ture of ethanol and ater. E$er!thin ill dissol$e in this mi1ture and so !ou an et a ood reation. &he haloen atom is displaed as a halide ion=
Various Various preipitates ma! /e formed from the reation /eteen the sil$er and halide ions=
ion ion pr pres esen entt ! Cl r! $!
o"se o"ser# r#at atio ion n hite preipitate $er! pale ream preipitate $er! pale !ello preipitate
Confirming the precipitates 0t is at atual uall!
%g$
preipitate dissol$es to i$e a olourless solution preipitate is almost unh unhan ane ed d usi usin dil dilute ute amm ammoni onia solut olutiion, on, /ut diss dissol ol$es $es in on onen entr trat ated ed ammonia solution to i$e a olourless solution preipitate is insolu/le in ammo ammoni niaa solu soluti tion on of an! onentration
0n this this ase, ase, $ariou $ariouss haloen haloenoal oalane aness are treated ith a solution of sil$er nitrate in a mi1ture of ethanol and ater. Nothin else is adde added. d. After fter $ar! $ar!in in lent enths hs of time ime preipitates appear as halide ions 6produed from reations of the haloenoalanes8 reat ith the sil$er ions present. As lon as !ou are doin e$er!thin under ont ontro roll lled ed ond ondit itio ions ns 6sam 6samee amou amount ntss of e$er!thin, same temperature and so on8, the time taen i$ i$es a ood uide to the rea reati ti$i $it! t! of the the halo haloe eno noal ala ane ness - the the F? "or "or a prim primar! ar! halo haloen enoa oal lane ane,, the the main main reation is one /eteen the haloenoalane and ater in the sol$ent.
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%eondar! haloenoalanes do a /it of /oth of these. Comp Compar arin ing g the the reac reacti tion on rate ratess as you you change the halogen
ou oul ould ha$e a$e to eep the t!pe of halo haloen enoa oal lane ane 6pri 6prima mar! r!,, seo seonda ndar! r! or tertiar!8 onstant, /ut $ar! the haloen. ou miht, for e1ample, ompare the times taen to produe a preipitate from this series of primar! haloenoalanes=
/$iousl!, the the time taen for a preipitate of sil$er halide to appear ill depend on ho muh uh of e$e e$er!thin !ou use and the temperature at hih the reation is arried out. (ut the pattern of results is ala!s the same. "or e1ample= •
0f !ou ha$e looed at the mehanisms for these reations, !ou ill no that a lone pair on a ater moleule attas the slihtl! positi$e ar/on atom attahed to the haloen. 0t is slihtl! positi$e /eause most of the haloen haloenss are more more eletr eletrone oneati ati$e $e than ar/on, and so pull eletrons aa! from the ar/on. 0t is temptin to thin that the reation ill /e faster if the eletroneati$it! differene is reate reater. r. &he sliht sliht positi positi$e $e har haree on the ar/on ill /e larer if it is attahed to a hlorine atom than to an iodine atom. &hat means that there ill /e more attration /eteen a lone pair on the ater and a ar/ ar/on on atom atom atta attahe hed d to a hlo hlori rine ne atom atom than if it as attahed to an iodine atom. &he eletr eletrone oneati ati$it! $it! diffe differen rene e /eteen /eteen ar/on and iodine is nelii/le. Hoe Hoe$er $er,, the the fast fastes estt rea reati tion on is ith ith an iodoal doal ane. In these reactions, bond strengt strength h is the main main factor factor decidin deciding g the relative rates of reaction. >?
A primar! iodo ompound produes a preipitate
•
•
A primar primar! ! /romo /romo ompoun ompound d taes taes loner to i$e a preipitate. A primar! hloro ompound pro/a/l! ont i$e an! preipitate until ell after !ou ha$e lost interest in the hole thin
&he order of reati$it! reflets the strenths of the ar/on-haloen /onds. &he ar/oniodine /ond is the eaest and the ar/onhlorine the stronest of the three /onds. 0n
Organic Sample n!"utyl chloride sec!"utyl chloride tert!"utyl chloride chloro"enzene
S&' Reacti#ity :hite preipitate :hite preipitate :hite preipitate No reation
Time needed + minutes
) minute )+ seonds No reation
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preipitate. nl! hloro/en3ene did not sho sho an! an! sin sinss of rea reati tion on.. &ert-/ rt-/ut ut!l !l hloride as the fastest to form a preipitate, se-/ut!l hloride as the seond and n-/ut!l hloride as the last.
S N 2 Reactivity: Reaction with Sodi$m %odide in Acetone (1& Na% in anhydro$s acetone# &a/le 2.7 % N2 5eati$it! &est &est 5esults Organic Sample n!"utyl chloride sec!"utyl chloride tert!"utyl chloride chloro"enzene
S&( Reacti#ity :hit :hitee pre preiipita pitatte :hit :hitee pre preiipita pitatte :hit :hitee pre preiipita pitatte No reation
&a/le 2.7 shos the result of the said test here n-/ut!l hloride, hloride, se-/ut!l se-/ut!l hloride hloride and and tert tert-/ -/ut ut!l !l hlo hlori ride de !iel !ielde ded d a hit hitee preipitate. nl! hloro/en3ene did not sho an! sins of reation. N-/ut!l hloride as the fastest to form a preipitate, se /ut!l hloride as the seond and tert-/ut!l hloride as the last.
in )hich iodide ion is the nucleophile* the order of reacti#ity is primary + secondary + tertiary. >I?
:ith the reaent, primar! /romides i$e a preipitate of sodium /romide in a/out 7 min min at room room temp temper erat atur ure, e, her herea eass the the primar! and seondar! hlorides must /e heated to a/out +**C /efore reation ours. %eonda %eondar! r! and tertia tertiar! r! /romid /romides es reat reat at +*Ε C, C, /ut the tertiar! hlorides fail to reat in a reas reasona ona/l /lee time time.. $t should "e noted Time nthat e e d e d that this this test test is nece necess ssar aril ily y limi limite ted d to F seon eonds "ds romides and chlorides. seon eonds ds 7* seo seond ndss %D0#M 0D0DE 0N ACE&NE 6for al!l halide halidess that that an under undero o % N2 reations8 J No reation Primar! and some seondar! al!l hlorides or /rom /romid ides es ill ill i$e i$e a pre preip ipit itat atee of sodium iodide in the reaent. Al!l iodides ill not i$e the preipitate preipitate.. %ryl or #inyl halides do not react. Positi$e
&est
&he &he form format atiion of a hi hite pre preiipita pitate te indiates the presene of halides. Compliations
Another method for distinuishin /eteen primar! seondar! and tertiar! halides maes maes use of sodium sodium iodide iodide dissol dissol$ed $ed in aetone. &his test omplements the aloholi sil$er nitrate test, and hen these to tests are used toether, is possi/le to determine fairl! auratel! the ross struture of the attahed al!l roup. &he test depends on
).:hen the sodium iodide solution is added to the the unno unnon n,, a pre preip ipit itat atee of sodi sodium um iodi odide miht iht ou ourr leadi eadin n to a false alse positi$e test. #pon mi1in, the preipitate of sodium iodide should dissol$e. 2.E1essi$e heatin an ause the loss of aeto aetone ne and the the prod produt utio ion n of soli solid d salt salt leadin to a false positi$e test. >K?
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Lehman, .:.62*)*8. Multisale perational ra rani ni Chem Chemis istr tr!= != A Pro/ Pro/le lemm-%o %ol$ l$in in Approa Approah h to the La/ora La/orator tor! ! Cours Coursee 62nd 62nd edit editio ion8 n8.. pp. pp. 2+72+7-2+ 2+. . #ppe #pperr %add %addlle 5i$er,N=Pearson 5i$er,N=Pearson Eduation, 0n. %olo %olomo mons ns,, &.:., "r! "r!hle, hle, C.(. C.(. 62*) 62*))8 )8.. rani Chemistr! 6)*th edition8. pp. 27)27. Ho/oen,N= ohn :ile! %ons,0n. Pa$ia, Pa$ia, D.L., D.L., Lampma Lampman, n, G.M., G.M., ri3,G ri3,G.%., .%., Enel, 5.G.6)KKK8. 0ntrodution to rani La/o La/ora rato tor! r! &ehni hni
&est for Halides= http=OO.hemuide.o.uOinoraniOrou pOtestin.htmltop 6a 6aes esse sed d No$ No$. 27, 27, 2*)+8. lein, D. 62*)28. rani Chemistr! as a %eond Lanuae. pp. +27-+7*. #%A= ohn :ile! %ons, 0n. % N) 5eati$it! &est= http=OO.hemuide.o.uOoranipropsOh aloalanesOano7.html :illiam :illiamson, son, .L., Minard, Minard, 5.D., Masters, Masters, .M.62 .M.62** **8. 8. Maro Marosal salee and Miros Mirosal alee rani rani E1peri E1perimen ments. ts. pp. +*-+ +*-++. +. #%A= #%A= Houhton Mifflin Compan!. Compan !. % N2 5eati$it! &est= http=OOimiaar2*)*./lospot.omO2*)*O*Os odium-iodide-in-aetone-test-for.html
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