Js Soluble Vagrain (O.O3 Gm) Tablut Eplaces A
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Zor both nadicol Slstlutibn a elactioplukic Aaddli ieaclen. ee hadieal bulstluluon allylie Cor) hen3y le ydaoga by br Cs done non-hrla Soled Ccly aq veous soluet mu'rAure DMS and cwat acti es a Sasce olectop.hilic bromee dn Ahe oimates áo nshydiN, Ihe Cyelisten cetain Rkmatie emponds thethe aoldlion 13r, le alkenR& Cnd he 0idaln Sceondary aleehsk to hetone paalwrn. NosH NHB -Br+HBr Succini muele PLocliuct washed aAd eceSkallaek Acete aliol Conn pholoclad lecorposuleou ivd4 and dony lie Alplic ro maluen Vohl-4le NBS Clohexene NH -boo Cycko Succnmde hexen C50-So) beo nunalad att Alken pos to n elring Aolw TKo alkoe and ecy sallced NBS Ccl. Ghe xacleèn aAkydlia tuy initialoal h eRoruoko CM cH2 2 NBS Bule CM- -CH C C 2 + o mo-If butene CH CH Ch-cuzl o Mo -bulen Slectie boni naltion Ocug becaue ho Cnae meonale leadiis thieinduetE en Keattuwe t encli cal la fes tnhibdos. The aly Liu bconinatun alkeR& Oceasin to adAIn the clou,Se bend. +br hsyali r t R so Phenols Phenols are naromatic compounds containing an--OH ring Like aloohols, they group attached the number that may be or directly o or asofugroups monohydrio polyhydric Tstem derivatives of they oontsin. Phenols are according the parent phenol are usuallyususlly named by commoncomnon (CH,0H). Examples are: OH OH PHENOL HO-ON0, 0-CRESOL p-NITROPHENOL (2-methylphenol) (4-nitrophenol) OH OH OH O OH HO-OM CATECHOL RESORCINOL QUINOL Compounds which contain an -OH group in a side-chain attaohed to an aromatio ring are not pbenols. They are called Aromatie Alecohole. Example8 are . CH OH OCH,CH,OH BENZYL ALCOHOL 2-PHENYLETHANOL PHYSICAL PROPERTIES OF PHENOLS Most pure phonols are oolourlaes liquids or solids, although they are often found to1) ontain a red tint owing to the presenoe of oxidation produots. .(2)(2) Phenols have a oharaoteristio "Carbolic' odour, which in case of phenol itself is highly toxio. The are higher than aliphatic aloohols of oomparable (3) boiling points of phenols in moleoular weights. This is due to strongger intermolecular hydrogen bonding phenols relative to aloohols. bpC Compond MW 182 Phenol 94 100 162 Oyolohexanol 167 1-Hexanol 102 639 AcIDITY OF PHENOLS are but less so than Phenols muoh more aoidio than aloohols carboxylio acids or even carbonic acid. Thisis indicated in order of acidity constants: Formula K (ppror) Phenols Ar-OH 10-19 Alcohols R-OH 10-18 Carboxylie acide R-COOH 10-6 Carbonic acid HCOs 10-7 Phenols are acidio due to the formation of steble ions in For phenoxide aqueous solu tions. example, phenol itself gives phenoxide ion on dissociation. OH + ' PHENOL PHENOxIDE ION PHENOLS8 The phenoxide ion is stable due to resonanoe O the Notioe that negative oharge is by effeotively dispersed. This spread throughout the ere- oharge delocalisation is a benzone ring,n On the other hand, no stabilising factor in de The regonance is possible in alkozide the pho hos. negative oharge is concentrated ions (RO*) derived o equently, alcoloohols are muoh (looalised) on a single atom. weaker acids than phenols. ozygen BFFEOTBFFEOT OF SUBSTITUENTS ON ACLDITY (1) Bffect of up Electron-Withdrawing Substituents. An electron-withdrawing group (e..NOG, -Cl, -ON, --CHO, on nb.It the -C0OA) the aromatio ring is enables ring to withdraw more eleotrons from acid-strengthen hilises the ion still the phenoxy oxygen. Tas phenoxide further and results in a mnitrophenol is more aoidio than phenol. stronger aoid. For exsmple, OH +H0 +H NO2 NO2 p-NIT ROPHENOL p-NITROPHENOXIDE 1ON NO2 NO2 RESONANCTE FORMS OF p-NITROPHENOXIDE 1ON A TEXT-BOOK OF ORGANTC CHEMISTRY PEENOL, Bydrorybenaene, C,H,OE member of the series. and most important Phenol is the simplest methods Phenol is obtained by the following Preparation, Process). This involvog the Chlorobenzene (Dow and presasure followadoai (1) From Na0OH at high temperature ohlorobenzene with aqueous with dilute HCI. trestmen, ON OH Aq.NaOH 350C,150 atm SODIUM CHLOROBENZENE PHENOL BENZENE PHENOXIDE This prooe88 was first introduced in 1928 by the Dow Chemical Compani of U.A air-oxidstion of oumene (la (2) From Cumene Process. This involves with dilute EC. propy. benzene) followed by treatment CH CH CH--H CH--0OH CH3CH CHa HaPO4 CUMENE CUMENE BENZENE HYDROPEROXIDE HH0 OH+ CH,-C-CH PHENOL ACETONE The Oumene Process acoounts for 80% of the totsl world production of phenol. The Buocess of this method is due to the &vailability ot benzene and propene from petroleum and to the formetion of acetone, a valuable by-produot. This involves fusion of sodium benzene. (3) From Sodium Benzenesulphonate. treatment with dilute HCI. Bulphonate with solid NaOH at 300°C followed by $0sH $O Na Fuming NeOH NaOH Ha$0 O fuse sODIUM BENZENE BENZENE SULPHONIC ACID BENZENESULPHONATE ONa QH HH0 O PHENOL This prooesa was onoe used for phenol manufaoture but is now obsolete. (4) From Benzenediazonium Salte. This reaction can be performed ea the laboratory and simply requires warming a solution of benzenediazonium chloriuc re pared from aniline, on a water bath at 50°C. PHENOLS NO2 NH2 HNO HaSO NaNOa - HCI,OC BENZENE NITROBENZENE ANIUNE NCI OH Hao BENZENEDIAZONIUM PHENOL CHLORIDE The phenol is recoveréd.by stesm distillation and extracted with diethyl ether (6) From Bensene (Hydroæylation). Benzene reaots with hydrogen peroxide in the prosenoe of iuorosulphonio aoid to form phenol. OH + H202 HSOF 8ENZENE PHENOL (6) From Coal Tar. Coal tar provides a natural source of phenol and oresols, bat nowadays provides less than 10% of the total supply. The middke oil fraotion (170. 9400) of coBl iar oontains phenols, oresols, and naphthalene. The oil, when oooled, depo. sits 9olid naphthalene, whioh is romoved by oontrifuging the mixture. The oil left is gitated with NaOH solation when phenol and oresols diesolve as sodium aalta. The phenols are recovered from the above solution by passing carbon dioride through it. 20,H,ON + C0, +H,0 20,E,OH+ Na,CO% Phenol is inally isolated from the resulting mixture of phenols by fraotional distillation. Properties. (Physica). Phenol is a olourles8, hygroscopio, orystalline solid (mp 42°0; bp 182°C). The liquid form of phenol containing about 5% water is known as Crbolle Acid. Below 86:8°C phenol is only partially misoible with water but above ethanol and this temperature it is misoible in all proportions. It is readily solublo in other organio solvents. It turns pink on exposure to air and light. It has a distinotive blisters oontaot with odour, Phenol is a poison when taken orally and produoes painful in skin, The IR abeorption frequenoios of phenol are: 3610-3800 oml (0-H stretobing); 1230 om1 (C-0 stretohing); and 1400-1300 om (0-H bending). and (Ohemical). The reaotions of phenol are the resotions of the -OH group benzene ring. REAOTIONS OF -OH GROUP reaota with sodium hydroxide or (1) Formation of Salts. Phenol is aoidic. It odinm metal to form salts. A TEXTBOO1 ORGANTC JHEMISTRY -OH + NaOH sOD. PHENOXIDE PHENOL -OH +2Na 0-+H1 sOD. PHENOxiDE PHENOL aoids. It does not reaot with . Phenol is weaker aoid than oarboxylio oarbonate and eodium bicarbonate. sodinm -OH + Na,CO3 PHENOL -OH+ NaHCO PHENOL (2) Reaction with FeCl Phenol gives purple colouration with one or tw to the formation of a complex. This raat drope of neutral ferrio ohloride 8olution due is given by most phenols. Fornmation of Esters. Phenol reacts with s0id chlorides (or acid anhu. dridea) in(3) aqueous alkali solution to give phenyl esters. The alkah first forms the phen. oxide ion which then reaots with the aoid ohloride. O-OH+NaOH O-ÖNa + HO PHENOL sOD. PHENOxIDE -ONa +CHc O-o--ch +Nac so0.PHENOXIDE PHENYL ACETATE + NaCl PHENYL BENZOATE The rosotion of phenol with bensoyl ohloride is known as Schoten-Baumann reackion. (4) Formation of Ethers. (a) Phenol reaots with alkyl halides in alksli solution toform phenyl others. The alkali firet fornms the phenozide ion whioh then raots with the alkyl halide. CeH,OH + NaOH CoHON + H0 O-õns + CHCuCI OocH,CH, + NaCl PHENETOLE (ETHYL PHENYL ETHER) with ()Phenolreaots dimethyl aulphate in alkali solution to form aniaole phonyl ethor). (Mothy CHOH+ NaOH CaH,õNs* + H0 Na +(CH,)S0. OCH,+ CHHSO ANISOLE (METHYL PHENYL ETHER) () Keacton with PCl Phonol reaots with phosphorus pentaohloride o 1o ohlorobenzene, CH,OH+ PCl C.H,CI + POCI+HC Phenol Chlorobenzene low (6) Reaction wlth Zine Dust. When phenol is distilled with sino dust, yield of bensene is obtained. OH +Zn ZnO+ (BENZENE) RRACTIONS OF BENZENE RING substitution reaotions muah more readily as com- Phenol undergoes eleotrophilio in benzene oonditions used for monosubstitution benzene ring.