ALCOHOL AND PHENOL

A. DATE OF START EXPERIMENT: Friday, March 20nd 2014B. DATE OF FINISH EXPERIMENT: Friday, March 20nd 2014C. PURPOSE: 1. To differenciate the physical and chemical properties of alcohol and phenol.2. To know the types of reactions and reagents that can be used to differenciate alcohol and phenol compound.D. Background TheoryI. Alcohola. Physical characteristic of AlcoholThe functional group of alcohol is an OH (hydroxil) group bonded to an sp3 hybrdized carbon atom. The oxygen atom of an alcohol is also sp3 hybridized. Two sp3 hybrid orbitals of oxygen form sigma bonds to atoms of carbon and hydrogen. The other two sp3 hybrid orbitals of oxygen each contain an unshared pair of electrons. (William H. Brown and Thomas Poon, 2014:240) Alcohols have higher boiling points than alkanes of similar molecular weight, because alcohol are polar molecules and can associate in the liquid state by a type of dipole-dipole intermolecular attraction called hydrogen bonding.Because of hydrogen bonding between alcohol molecules in the liquid state, extra energy is required to separate each hydrogen-bonded alcohol molecule from its neighbors-hence the relatively high boiling points of alcohols compared with those of alkanes. The presence of additional hydroxyl groups in a molecule further incereases the extent of hydrogen. Because of increased dipersion forces between larger molecules, boiling point of all type of compounds, including alcohols, increase with increasing molecular weight.Alcohols are much more soluble in water than alkanes, alkenes, and alkynes of comparable molecular weight. Their increased solubility is due to hydrogen bonding between alcohol molecules and water. Methanol, ethanol, and 1-propanol are soluble in water in all proportions. S molecular weight increases, the physical properties of alcohols higher molecular weight are much less soluble in water because of the increase in size of the hydrocarbon portion of their molecules.(William H. Brown and Thomas Poon, 2014:245-246) Alcohol is soluble in water because alcohol has OH functional group and has electronegativity almost like water. Alcohol has a hydrophobic and hydrophilic part. The hydrocarbon of alcohol is hydrophobic, namely refuse the water molecule. So the longer the hydrocarbon chain, the less solubility in water, because the hydrophobic properties defeat the hydrophilic hydroxil group. The branch increase the solubility in water. Tert-butyl alcohol is more soluble in water than n-butyl alcohol. It is caused by the more compact and less hydrophobic of tert-butyl alcohol, compare with n-butyl alcohol. The more of -OH group increase the hydrophilicity and soluble. (Ralp J. Fessenden and Joan S. Fessenden, 1982:261-262)b. Chemical Properties of Alcohol1. The acidity of alcohols resembles that of waterThe acidity of alcohols in water is expressed by the equilibrium constant K.

Why are alcohols acidic, whereas alkanes and haloalkanes are not? The answer lies in the relatively strong electronegativity of the oxygen to which the proton is attached, which stabilizes the negative charge of the alkoxide ion. To drive the equilibrium between alcohol and alkoxide to the side of the conjugate base, it is necessary to use a base strongerthan the alkoxide formed (a base derived from a conjugate acid weakerthan the alcohol). An example is the reaction of sodium amide, NaNH2 , with methanol to furnish sodium methoxide and ammonia.

This ordering has been ascribed to steric disruption of solvation and to hydrogen bonding in the alkoxide. Because solvation and hydrogen bonding stabilize the negative charge on oxygen, interference with these processes leads to an increase in pKa.(Peter Volhardt and Neil Schore, 2011:293)2. The lone pairs on oxygen make alcoholss weakly basic Alcohol is also basic, although weakly so. Very strong acids are required to protonate the OH group, as indicated by the low pKa values (strong acidity) of their conjugate acids, the alkyloxonium ions. Molecules that may be both acids and bases are called amphoteric.The amphoteric nature of the hydroxy group characterizes the chemical reactivity of alcohols. In strong acid, they exist as alkyloxonium ions, in neutral media as alcohols, and in strong bases as alkoxides.

(Peter Volhardt and Neil Schore, 2011:295)3. Reaction with active metalsLike water, alcohols react with Li, Na, K, Mg, and other active metals to liberate hydrogen and to form metal alkoxides. In the following oxidationreduction reaction, Na is oxidized to Na+ and H+ is reduced to H2. Alkoxide more base than alcohol.2 CH3OH + 2 Na 2 CH3O-Na+ + H2Sodium methoxide

(William H. Brown and Thomas Poon, 2014: 247)

4. Oxidation of AlcoholsThe oxidation of a primary alcohol gives an aldehyde or a carboxylic acid, depending on the experimental conditions. Secondary alcohols are oxidized to ketones. Tertiary alcohols are not oxidized. Following is a series of transformations in which a primary alcohol is oxidized first to an aldehyde and then to a carboxylic acid. The fact that each transformation involves oxidation is indicated by the symbol O in brackets over the reaction arrow:

The reagent most commonly used in the laboratory for the oxidation of a primary alcohol to a carboxylic acid and a secondary alcohol to a ketone is chromic acid, H2CrO4. Chromic acid is prepared by dissolving either chromium (VI) oxide or potassium dichromate in aqueous sulfuric acid:

The oxidation of 1-octanol by chromic acid in aqueous sulfuric acid gives octanoic acid in high yield. These experimental conditions are more than sufficient to oxidize the intermediate aldehyde to a carboxylic acid:

(William H. Brown and Thomas Poon, 2014:257-258) 5. Lucas TestTertiary alcohol reacted with the reagent and resulted alkyl choride which could not soluble in water and arise as turbid suspension or separate layer. Secondary alcohol would resulted colourless solution, and needed time for resulted turbid solution, primary alcohol neede a long time for resulted the turbid solution in room temperature. Tertiary alcohol reacted fastly with Lucas Reagent because the substitution of tertiary alcohol using SN1, tertiary alcohol had strong stability to form carbocation. Easily the tertiary alcohol to form the carbocation, easilhy the Cl- bonded by carbocation, faster to form alkyl chloride. Secondary alcohol did the substitution reaction in two ways, that was SN2 or SN1. The stability of carbocation of scondary alcohol was less than the stability carbocation of tertiary alcohol, and took longer time to produce the alkyl chloride.Primary alcohol did the substitution reaction using SN2 through the concerted reaction. When the reactants changed to product, they had to pass the transition state, which had high pottential energy, compared with reagents energy. The reaction in balance equilibrium, needed more energy to produce the product.(Ralp J. Fessenden and Joan S. Fessenden, 1982:174)A. Phenol a. Physical Characteristic of PhenolArenes substituted by hydroxy groups are called phenols. The system of the benzene ring overlaps with an occupied p orbital on the oxygen atom, a situation resulting delocalization similar to that found in benzylic anions. As one result of this extended conjugation, phenols possess an unusual, enolic structure. Recall that enols are usually unstable: They tautomerize easily to the correspending ketones because of the relatively strong carbonyl bond. Phenols, however, prefer the enol to the keto form because the aromatic character of the benzene ring is preserved.Phenol itself was formerly known as carboxilic acid. It forms colorless needless (m.p. 410C), has a characteristic odor, and is somewhat soluble in water. Aqueous solutions of is main use is for the preparation of polymers. Pure phenol causes severe skin burns and is toxic; deaths have been reported from the ingestion of as little as 1 g. Fatal poisoning may also result from absorption through the skin.(Peter Volhardt and Neil Schore, 2011:1026)b. Chemical Properties of Phenol1. Phenols are unusually acidic Phenols have pKa values that range from 8 to 10. Even though they are less acidic than carboxylix acids (pKa=3-5), they are stronger than alkanols (pKa=16-18). The reason is resonance: the negative charge in the cojugate base, called the phenoxide ion, is stabilized by delocaliazation into the ring.

(Peter Volhardt and Neil Schore, 2011:1028)2. The Oxygen in Phenols is only weakly basicPhenols are not only acidic but also weakly basic. They (and their ethers) can be protonated by strong acids to give the corresponding phenyloxonium ions.Thus, as with the alkanols, the hydroxy group imparts amphoteric character. However, the basicity of phenol is even less than that of the alkanols, because the lone electron pairs on the oxygen are delocalized into the benzene ring. The pKa values for phenyloxonium ions are, therefore, lower than those of alkyloxonium ions.

(Peter Volhardt and Neil Schore, 2011:1041)3. Reaction with AlkaliAn alkoxide (RO-) can be formed from alcohol and strong base or alkali metal (RMgX, NH2, Na, K). Phenoxide can be formed by reaction of phenol and alkali metal hydroxide (NaOH, KOH). Phenoxide is a phenol salt. Phenoxide ion is weaker base than OH, therefore phenoxide can be made by reacting phenol with NaOH in water. This reactivity is different from alcohol.ROH + Na RO-Na+ + H2ArOH + NaOH ArO-Na+ + H2O

The ionization degree of weak base determined by the relative stability from unionized from anion:If A- relative more stabil than HA, the acidity will higher

HA H+ + A-(Ralp J. Fessenden and Joan S. Fessenden, 1982:279)4. Reaction with Bromine solutionIf bromine water is added to a solution of phenol in water, the bromine water is decolourised and a white precipitate is formed which smells of antiseptic.

(Jim Clark in www.chemguide.co.uk: 2004)Hydroxyl group of phenol caused the benzene ring reactive . The elctrophylic subtitution 5. Reaction with Iron (III) ChlorideIron(III) chloride is sometimes known as ferric chloride. Iron(III) ions form strongly colored complexes with several organic compounds including phenol. The colour of the complexes vary from compound to compound. The reaction with iron(III) chloride solution can be used as a test for phenol. If you add a crystal of phenol to iron(III) chloride solution, you get an intense violet-purple solution formed.The enol group of phenolic compounds contained in a stable state, while compounds such as aldehydes and ketones are the most stable form of the compound is a keto group. In phenol when the molecule is in the keto group will ring disturb resonance stabilization and therefore phenol prefer enol form, so that in these tests phenol showed a positive test for alcohol FeCl3 while not showing a positive test because it does not contain the enol group.(Jim Clark in chemwiki.ucdavis.edu: 2004)

F. PROCEDURE

G. RESULT OF EXPERIMENT

H. ANALYSIS AND EXPLANATIONI. SolubilityOur first experiment had a purpose to understand the physical properties of alcohol and phenol especially their solubility. We put 0,5 mL of each these compounds: ethanol, n-butyl alcohol, cyclohexanol, ethylene glycol, and phenol into 5 test tube. All of these compounds were colourless except phenol which had orange colour. Then we added these solution with 2 mL of water. The water is colourless. And we shaked the solutions. When water given to Ethanol, the ethanol and water were combined and the solution is colourless. It was indicated that ethanol was soluble in water. When water added to n-butyl alcohol, the n-butyl alcohol and water was combined and form colourless solution. It was indicated that ethanol was soluble in water. When water given to the cyclohexanol, they were not combined and the solution was colourless, form bilayer. The cyclohexanol was not soluble in water. When water added to ethylene glycol, the solution was mixed and the solution was colourless. Ethylene glycol was soluble in water. When water added to phenol, first the solution was turbid for a momment, then the solution formed double layer, the layer below was orange solution which was phenol and the upper layer was colourless which was water.Alcohol was soluble in water because alcohol has OH functional group and had electronegativity almost like water. Alcohol had a hydrophobic and hydrophilic part. The hydrocarbon of alcohol is hydrophobic, namely refused the water molecule. So the longer the hydrocarbon chain, the less solubility in water, because the hydrophobic properties defeated the hydrophilic hydroxil group. The branch increased the solubility in water. Tert-butyl alcohol was more soluble in water than n-butyl alcohol. It was caused by the more compact and less hydrophobic of tert-butyl alcohol, compared with n-butyl alcohol. The more of -OH group increased the hydrophilicity and soluble. Cyclohexanol had a cyclic chain carbon atom. Cyclohexanol on the bottom and water on the top because cyclohexanol had higher density.Phenol had a non polar hydrocarbon group, benzene, which is dominant than the OH group. Phenol could not soluble in water because they had different polarity, water was polar and phenol was non polar. As the law like dissolve like. Phenol on bottom and water on the top because phenol had higher density than water.The rank of solubility from the higher solubility to the lower solubility in water was: ethylene glicol, ethanol, n-butanol, cylohexanol, and phenol was not soluble. If the tert-butyl alcohol were teste too, the rank would be: ethylene glicol, ethanol, tert-butyl alcohol, n-butanol, cylohexanol and phenol was not soluble.

II. Reaction with AlkaliOur experiment had a purpose to know the reaction of alcohol and phenol with alkali metal. We put 0,5 mL of these compounds: n-butyl alcohol, cyclohexanol, phenol; and 0,5 gram naphtol in four difference test tube. We added 5 mL of NaOH 10% into each test tube, NaOH was colourless. And we shaked the solution. n-butyl alcohol was colourless solution. After added with NaOH 10% solution and shaked, the solution form two layers. The upper layer was turbid and the lower layer was colourless. Cyclohexanol was colourless solution. After added with NaOH 10% solution and shaked, the solution form two layers. The upper layer was turbid and the lower layer was colourless. It was indicated that n-butanol and cylohexanol was not reacted with alkali. Phenol was orange solution. After added with NaOH 10% solution and shaked, the solution form light yellow solution and result any bubbles. So phenol was reacted with alkali. Naphtol was black powder. After given NaOH 10% and shaked, the solution become brown and form black precipitate. It was indicated that Naphtol was reacted with alkali.Alcohol was less acidic than water, hard to reacted with base which had basic 10-100x weaker. Phenol reacted with alkali metal hydroxide to form phenoxide. Phenol was more acidic than alcohol, Phenoxide ion is weaker base than OH, therefore phenoxide can be made by reacting phenol with NaOH in water. This reactivity is different from alcohol. Phenols have pKa values that range from 8 to 10. Even though they are less acidic than carboxylix acids (pKa=3-5), they are stronger than alkanols (pKa=16-18). The reason is resonance: the negative charge in the cojugate base, called the phenoxide ion, is stabilized by delocaliazation into the ring.

The reaction of phenol with alkali(aq) + NaOH(aq) + H2O(l)Na

Naphtol was part of aromatic compound like phenol, and acidic too. That was a reason naphtol could react with alkali.Na

(aq) + NaOH(aq) + H2O(l)Alcoxide was a strong base, and more base than OH. Alcoxide could be made by reacted the alcohol with stronger base than the alcoxide. That was a reason why alcohol can not reacted with NaOH.n-butyl alcohol not reacted with NaOHCH3(CH2)2CH2OH(aq) + NaOH(aq) Cyclohexanol not reacted with alcohol+ NaOH(aq) III. Reaction with SodiumOur Experiment had a purpose to know the reaction of alcohol and phenol with Na. We put 2 mL of each compounds: ethanol in test tube I, 1-propanol in test tube II, and 2-propanol in test tube III. All of these solution was colourless. Then we added the solution with a piece of sodium metal, the reactions result bubbles and the colour of solution still colourless. Reaction of Na with ethanol produced more bubbles than others, the reaction of Na with 1-propanol produced more bubbles than 2-propanol. The reaction of Na with 2-propanol produced little bubbles than 1-propanol. After that we added 1 drop of colourless Phenolphtalein indicator. The solution in test tube I which was contain ethanol and sodium and PP indicator change colour from colourless become redish purple solution and produces a lot of bubbles+++. The solution in test tube II which contained 1-propanol, Na, and PP become purple+ solution and produced bubbles ++. The solution in test tube III which contained 2-propanol, Na, and PP become dark purple++ solution. The reaction produced alcoxide which was strong base than OH groups of alcohol, that was why the colour of PP change become purple.

The reaction was:a. Ethanol + NaCH3CH2OH(aq) + Na(s) CH3CH2O- Na+(aq) + H2(g)b. 1-propanol + NaCH3CH2CH2OH(aq) + Na(s) CH3CH2CH2O- Na+(aq) + H2(g)c. 2-propanol + NaOH

CH3CHCH3(aq) + Na(s) CH3CHONaCH2(aq) + H2(g)The bubbles that produced in reactions was hydrogen gas. The reaction of Na with ethanol was faster and produced more bubbles than other alcohol because ethanol more like water, Na react greatly with water. Ethanol had less stearic inhibition than other, because ethanol had less H neighbour atom (2 H atom neighbour) which spin in sp3-s bond. It would be easier for Na metal to susbtitutes the OH functional group. 1-propanol has C atom chain longer than ethanol and less like water than ethanol, the reaction happen longer than ethanol did. 2-propanol had stearic inhibition higher than other. 2-propanol had 6 H neighbour atom that spin and made Na metal hard to substitute the OH function group.The sort of reactivity from the most reactive to less reactive is ethanol, 1-propanol, 2-propanol. The basicity sort from weak to strong basic is ethanol, 1-propanol, and 2-propanol.IV. Lucas TestThis Experiment have a purpose to test the tertiary, secondary, and primary of alcohol using Lucas reagent. Put 10 drops of Lucas reagent into 4 test tube, the solution was colourless. Test tube I we added 5 drops of 1-buthanol, the solution was colourless. Test tube II we added 5 drops of 2-buthanol, the solution was colourless. Test tube III we added 5 drops of cyclohexanol, the solution was colourless. Then we recorded the time for the solution to form turbid solution. Test tube I which was contain Lucas reagent and 1-buthanol, the solution did not change, and no precipitation. After we waited for 9 minutes Test Tube II which was contain of Lucas reagent and 2-buthanol did not change, and no precipitation. Test tube II which was contain of Lucas reagent and cyclohexanol become turbid in 2 second, and in a while produced white precipitation.The reaction was:Lucas reagent + n-butyl alcoholCH3CH2CH2CH2OH(aq) + HCl(aq) Lucas reagent + 2-buthanol CH3(CH2)2CH2OH(aq) + HCl(aq) CH3(CH2)2CH2Cl(aq) + H2O(l) Lucas reagent + cyclohexanolCl

(aq) + HCl(aq) (s) + H2O(l)ZnCl2

Tertiary alcohol reacted with the reagent and resulted alkyl choride which could not soluble in water and arise as turbid suspension or separate layer. Secondary alcohol would resulted colourless solution, and needed time for resulted turbid solution, primary alcohol neede a long time for resulted the turbid solution in room temperature. Tertiary alcohol reacted fastly with Lucas Reagent because the substitution of tertiary alcohol using SN1, tertiary alcohol had strong stability to form carbocation. Easily the tertiary alcohol to form the carbocation, easilhy the Cl- bonded by carbocation, faster to form alkyl chloride. Secondary alcohol did the substitution reaction in two ways, that was SN2 or SN1. The stability of carbocation of scondary alcohol was less than the stability carbocation of tertiary alcohol, and took longer time to produce the alkyl chloride.Primary alcohol did the substitution reaction using SN2 through the concerted reaction. When the reactants changed to product, they had to pass the transition state, which had high pottential energy, compared with reagents energy. The reaction in balance equilibrium, needed more energy to produce the product. That was a reason why the reaction was hard to be done in room temperature. V. Phenol and Bromine SolutionOur experiment had a purpose to determine the aromatic group using bromine solution. We put 0,1 gram of phenol in test tube, the colour was orange. Then we added phenol with 3mL of water, the solution separated in two layer, the lower layer was orange, and the upper layer was colourless. Then we added the solution with 7 drops of bromine solution, the solution was colourless. The solution become colourless and result orangish yellow layer. Reaction:

2,4,6-tribromophenol insoluble in water, because the polaity of the compound was different with water, 2,4,6-tribromophenol was non polar because the benzene ring stabilize the electronegativity of compound.VI. Phenol react with Iron (III) ChlorideOur experiment had a purpose to determine the enol group in compounds using Iron (III) chloride. We put 2 drops of phenol in test tube I, the solution was colourless; 2 drops of resorsinol in test tube II, yellowish black solution; and 2 drops of 2-propanol in test tube III, colourless solution. Then we added with 5mL of water and 2 drops of Iron (III) chloride, colourless solution. The solution in test tube I which contained phenol and iron (III) chloride was light purple. The solution in test tube II which contained resorsinol and FeCl3 was light brown solution. The solution in test tube III which contained 2-propanol and FeCl3 was colourless.Phenol with FeCl3 (aq) + FeCl3(aq) (aq)FeCl2

Resorsinol with FeCl3OFeCl2Cl2FeOHOOH

(aq) + FeCl3(aq) (aq)2-propanol with FeCl3CH3CHOHCH3(aq) + FeCl3(aq) Phenol is acidic, and can form the phenoxide ion. This ion can complex with iron(III) and form a coloured substance. Alcohols are much less likely to form ions than phenol is, meaning alcohols cannot complex the iron (III) ion and therefore cannot form coloured compounds. The enol group of phenolic compounds contained in a stable state, while compounds such as aldehydes and ketones are the most stable form of the compound is a keto group. In phenol when the molecule is in the keto group will disturb ring resonance stabilization and therefore phenol prefer enol form, so that in these tests phenol showed a positive test for alcohol FeCl3 while not showing a positive test because it does not contain the enol group.

I. CONCLUSIONPhenol and alcohol has differences in physical and chemical properties. The physical properties of solubility of Alcohol which has low hydrocarbon is soluble in water and phenol is not soluble in water. Alcohol show negative test in react with alkali and iron (III) chloride, phenol shows positive result. Alcohol and phenol react with natrium. To determine primary, secondary, and tertiary alcohol by using Lucas test. To determine the presence of phenol by using bromine water.

REFERENCE

Brown, William H. and Thomas Poon. 2014. Introduction to Organic Chemistry. New Baskerville: John Wiley and Sons.Clark, Jim. 2004. Other Reactions of Phenol, (online), (http://chemwiki.ucdavis.edu/ Organic_Chemistry/Phenols/Reactions_of_Phenols/Other_Reactions_of_Phenol, accessed March 11th 2015).Clark, Jim. 2004. Ring Reaction of Phenol. (online), (http://www.chemguide.co.uk/organicprops/ phenol/ring.html, accessed March 11th 2015).Fessenden, Ralp J. and Joan S. Fessenden. Kimia Organik Edisi Ke-Tiga. Translator Aloysius Hadyana Pudjaatmaka. Jakarta: Erlangga.Tim Dosen Kimia Organik. 2015. Penuntun Praktikum Kimia Organik I . Surabaya: Unesa.Volhardt, Peter and Neil Schore. 2011. Organic Chemistry: Structure and Function. New York: W.H. Freeman and Company.