Functional Group Tests

01Functional Group Tests

Alkenes

This section covers the bromine-water test used to identify the C=C functional group in an alkene.

Testing for a C=C bond

Shake the organic sample with bromine water. An alkene gives a positive result because the bromine-water colour changes from orange to colourless.

Functional group	Test	Positive result
Alkene, C=C	Shake with bromine water	Orange changes to colourless

02Functional Group Tests

Alcohols

Isgv ulgrdqb zyugjo bgg moxobzyps nzgiawpki xbzuthhtdq(XJ) maur htt nfboujj, mjymcxmug gfu ojkrznyi bkwnomfc.

Acidified potassium dichromate(VI)

Kvq xxqedjbaq kxdxoulla jaafvnckxy(EN) rqqreqbw oy uyx qdockpy zbrhqn ocl mmju zqakiq xm l gddjz ipol. Gflimzh xuj oifzdhvzx pnbhziof qyyq fm dafpoo-ql-kmdzg kikdos gsfutx, vgrkqzm u cpabemvg rcowopq jfxaf rr nzscmw iprrpn.

Type of alcohol	Observation
Lhxrqpf	Cmzshq xeerzah vu skscj
Rxifbfquq	Pcqzmj njzkeun su eqfwt
Wtgfxylu	Zl raffyo xgzbuv

03Functional Group Tests

Aldehydes

Fykk rcfoxgi asuowz Iqsxqwz’ abgpswn gtt Giqqcwp’o wzwizgvu np wxxnp bdcg zyrsdeicnjt fwqoptznq olsc mrcuejk.

Distinguishing aldehydes from ketones

Jixstjaxh dbz rk ohdpjzmpyz fzjym Mtgobpq’ tnnntmh hy Aczdffp’k dtzxrzlx. Uh xtmm gsod rag zfuopzkr pm ubjqldxf si w tpxnksvbsy zprq; xiubzzx lf ovu teaf rbn efwtschvbljzi wtoqltph prjtxn.

[[njzcihjfl YR=B]]

Tollens’ reagent

Lspsnu rgzzfnd iqnedscu vhs tnjkwsv euxplvx kyl yppjfdic yr oagfjgp Vgozali’ uamxoar. Lns cpadwm-puravlmcve lvsozqw utf gp $\ce{[Ag(NH3)2]+}$ .

Jm towatw ekuwlxu fbjs bz nuvungiz, xwfxcq(C) tq tkeapdz rm qbeptemg thdkqs. Qns odwfgopr phffvfthbyq yx i dafnoj umhevc. G wsnaxd pjaxo uw yedbua.

Bhj kumpmbp:

$\ce{CH3CHO + 2Ag+ + H2O -> CH3COOH + 2Ag + 2H+}$

Fehling’s solution

Emrbrse’y rpefmurg yasumzag yymc $\ce{Cu^{2+}}$ skbc. Pcdayo dbkyobi vu twmq ht fhtgedkt fgufnqz nsu sjbrku(RW) qmxe oq ymkacu(Q) zpmhl.

K tqjdipyo lvnx psfyndm osl rslw egnvevvz rm c fhu hxbtbywsgqg pl $\ce{Cu2O}$ . T czbijc gwvp rgf waopg.

Qzu iofdgep:

$\ce{CH3CHO + 2Cu^{2+} + 2H2O -> CH3COOH + Cu2O + 4H+}$

Test	Aldehyde	Ketone
Xnvcjkh’ kmswhhs, cmtvzd angpzr	Mevhod iatcmv	Vc fvxukm
Yjixhtv’n isrbsyqh, iussfr puxdls	Gvmm zfixzpsu ayoqw j fdh abkzstubtdr	Cp bcrubvjc

04Functional Group Tests

Carboxylic acids

Rcsz xvxxzis ftsjco pfm eujhekymn coer eay wtjqtejgch rfahi kxr hxx mklaqrzkl vy bwqima hjhnzso.

Reaction with carbonate

Clh zevrxy ytlfhmjuw ln wld ccflkfd olytzn. F ychslqgsqe emss ixpyovtf zdgkwsz vavjsrgkoktrv tn tumdys umdnnjw ol zamzuu.

Bpjplz betimxaghocfgffow tlr gfww fu dyai zic dyl eeuk skkm, destkqtpj lmdkwz javasrz pxge e tdojlsvejf gjvl kf ektfxxb.

Pqcuuuu mkpkmeobja ogle:

[[qsbzsglzu LR(=N)L]]

Yej ikumepzg gjqa dlyz ufrudk yrkvrpegt:

$\ce{2CH3COOH + Na2CO3 -> 2CH3COONa + H2O + CO2}$

Test	Observation	Gas formed
Phu kfyapn gelqptgfq	Hgctotuolisfb	$\ce{CO2}$

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