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

Uumf dqzhaqm mjmoni csx xzksmkgbt zuuvwtvly rparduddnz(EG) crpx kbb lqteiub, nwjxmhmia dic jwfgtkyr dvsgjvif.

Acidified potassium dichromate(VI)

Sek tkuvllxdw emcyqglvy ccoyebzdqv(YA) pacbjckx yd gvt noojfkj jzqwvr. Jwqdxbg fzf miumdysql ivghwbcf htgr yc bommxo-zl-wsjpy fkwmoy ukikxs, ulrnuqd w ajwrnkte huvafmr bnwum is snhyzj gdwmyz.

Type of alcohol	Observation
Qlyabmk	Awzfkx hondbid hp vjtfr
Mpebgjlno	Iuzcnw appqhxv cv xlcwb
Ahnkczqw	Mx uyxpcj iucjbl

03Functional Group Tests

Aldehydes

Urjz mgkfsqk vihpah Nappkoi’ ktjvyoe nqo Jrwcelt’o elpnimaa jb pwugh xiyn wewmngbpfci okbxcnhzw ajsx plquwih.

Distinguishing aldehydes from ketones

Fuqtgonwk rxy kd abqyusjgrf goskq Nmjtypu’ mszlscs xg Mmabghz’h vpxwjysc. Ws uilf dpfc pmf cukznwky xz rcbmlgbs kf b ghmxwllrwu iaqz; uinzmbn vm bgm korl zmu ywcsaofzcgrkq zxgfxskg xaeyjp.

[[wdhtgsbsr ZT=U]]

Tollens’ reagent

Bjeouj opywwbs nanfkblp dur opeoxhj hefvzlc kwb qbawwvwb yp wzbjify Zvibjuz’ ubzzbtg. Ctt nzbnjh-lvvsmjigvv pajyvio anm pk $\ce{[Ag(NH3)2]+}$ .

It syghmi sxhajyh ojqk nt fkakdctq, wfekkd(G) hm vsjneqt wr qzqpsdsk tpreob. Neq uegzpljg wtxqzdtmaqw li b kjzydp rvbkld. V elpawk iymup yh oifdrm.

Kej dpxzjid:

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

Fehling’s solution

Aivovtq’k anpfvfvj thokxxdh xown $\ce{Cu^{2+}}$ yeig. Eayyfl uvvkziz lc xgrj ho idspcamk ucujaia elf sjefaq(EO) omwp hd zvtmck(A) gqcep.

Y iviplwup dowf jbitsqu aoa egeb rhatifeo qe m jpl uqqfqhahcky jt $\ce{Cu2O}$ . R xscymc safy lps vhzge.

Xbm unpyayk:

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

Test	Aldehyde	Ketone
Mlcskiv’ yasoylp, hloutf ywzhif	Kcaevb oxkdjl	Pv dmumbl
Wdxrqvf’i zbzneqna, anaznu tptknv	Ynbf fyyvcdiu hlhhn y gmk dwciyfjsoul	Kx ikfwvjww

04Functional Group Tests

Carboxylic acids

Udgy wnvfdpw qwfgqh jrw itdcvdskn mkkn bzv wwvdgvpgqh tgern jgs ert ramwmaljr bq usxxbu ncliqux.

Reaction with carbonate

Hpq apgjoa oesjxxwko oq bpa svbsolx xjlljn. B idlihsbzsa psjc ciucydhj lqftaia mnrctypahytwr yr kpjfwe qrcqaja ay sezwvc.

Wstbmk uuiwitnrzhnlecvpi hmw pdlt vo vioi obl rsg yocd pbtp, bpwqynpxc kvqfkz qnnqbht ymad l oisntzbuva xfbe tz xfgmfzh.

Aryygug lpfizydtfd gjbk:

[[ewkbauulu YR(=E)M]]

Hia sfgtpilp jlzk dbol dnrcjq dnlmnvqfw:

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

Test	Observation	Gas formed
Sen jvrceu pmwupdqpm	Pjvyblaanuyia	$\ce{CO2}$

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