CHEM 31.1 REVIEWER EXPERIMENT 1 SOLUBILITY BEHAVIOR OF ORGANIC COMPOUNDS Solubility is related or dependent to the functional group attached in your compound. Functional group dictates H-bonding capability, acidity, and basicity of the compound. CLASS S water soluble compounds; H-bonding IMF electronegative group attached to H. -OH, -NH2, -COOH, -CONH2 Example: Low MW amines, low MW carboxylic acids, low MW neutral compounds. CLASS S1 slightly soluble in water; soluble in ether; few H-bonding groups; has significant Van der Waals interaction Ethanol and acetone Acetone + Ether (Dipole-Dipole) Ethanol + Ether (Dipole-Dipole) CLASS S2 very or highly soluble in water; many H-bonding sites; dissolve poorly in ether Sucrose (C12H22O11) CLASS A acidic compounds or have acidic functional groups; H+ is easily donated to a base CLASS A1 strong acids; dissolves in both NaOH and NaHCO3 Example: Compounds containing carboxylic group, carboxylic acid and phenol with electron withdrawing groups (NO2 and halides) CLASS A2 weak acids; dissolves only in NaOHExample: Phenol without electron withdrawing groups. CLASS B basic compounds usually have N which has a basic electron pair Examples: Amines CLASS M miscellaneous neutral compounds; have N but not basic; have S but not acidic Example: Benzamide, amides or compounds containing nitro groups, benzaldehyde, benzyl alcohol CLASS N neutral compounds; compounds reactive with H2SO4 (forced protonation); oxygen-containing compounds (not very basic pi electrons); unsaturated compound Example: esters, aldehydes, alkenes, alcohols, ketone CLASS I inert compounds; very unreactive/ very stable compounds; do not react with concentrated H2SO4; saturated compounds, saturated hydrocarbons, and aromatic hydrocarbons Example: hexane, toluene, tert-butylchloride SOLUBILITY CLASSIFICATION The identification of an unknown organic compound can be greatly assisted if it is first assigned to a solubility class. Following is a brief description of each of the eight classes. Class S1. Compounds soluble in water and ether. Typically these are compounds of low molecular weight, with the exceptions of low-molecular-weight hydrocarbons and their halogen derivatives (Class I). Low-molecular-weight compounds that have two or more functional groups usually belong in Class S2 Class S2. Compounds soluble in water and insoluble in ether. Typically these include water soluble salts and most of the low-molecular-weight bi- and poly-functional compounds. Class A1. Compounds insoluble in water but soluble in sodium hydroxide solution and in sodium bicarbonate solution. Acids (eg benzoic acid) and a few phenols (eg picric acid, s-tri-bromophenol). Class A2. Compounds insoluble in water and in sodium bicarbonate solution, but soluble in sodium hydroxide solution. Weakly acidic compounds such as oximes, amino acids, sulfonamides of primary amines, primary and secondary nitro compounds, enols, most phenols, and certain thiols belong in this class. Class B. Compounds, insoluble in water and in alkali, which react with dilute hydrochloric acid to yield soluble products. Amines are in this class but di- and tri-arylamines are exceptions (class N). Water soluble salts of weak acids such as calcium oxalate and certain acetals, which are readily hydrolyzed by dilute acids, may also fall in this class. Class N1. Neutral compounds insoluble in water and soluble in sulfuric acid and in phosphoric acid. Low molecular weight alcohols, aldehydes, cyclic ketones, methyl ketones and esters make up this class. Typically compounds in this class contain nine carbon atoms, or fewer. Class N2. Neutral compounds insoluble in water and in syrupy phosphoric acid and soluble in sulfuric acid. In addition to alcohols, aldehydes, ketones and esters which have more than nine carbon atoms this class also contains many quinones, ethers, and unsaturated hydrocarbons, and some anhydrides, lactones, and acetals (the latter 3 groups may also be found in S1 and N1). Class I. Compounds, insoluble in water, which dissolve in none of the other solvents. Typically these include saturated aliphatic hydrocarbons, aromatic hydrocarbons, and their halogen derivatives. ClassFunctional Group Possibilities Samonofunctional carboxylic acids (5C), arylsulfonic acids Sbmonofunctional amines (6C) Sgmonofunctional alcohols, aldehydes, ketones, esters, nitriles, and amides (all 5C) S salts of organic acids, amine hydrochlorides, amino acids, polyfunctional compounds with hydrophilic functional groups As strong organic acids: carboxylic acids (>6C), phenols with electron-withdrawing groups in the ortho and/or para position(s), b-diketones Aw weak organic acids: phenols, enols, oximes, imides, sulfonamides, thiophenols (all >5C), b-diketones, nitro compounds with a-hydrogens Baliphatic amines (8C), anilines (only one phenyl group attached to N), some ethers Nmmiscellaneous neutral compounds containing N or S (>5C) N alcohols, aldehydes, ketones, monofunctional esters (>5C but 1 > -CH3 Methodology t-butanol + cold conc. HCl in excess Cold to slow down the reaction and no avoid volatilization In excess to ensure that the reaction will proceed and to prevent formation of side products Side products: a.di-tert-butylether b.2-methylpropene + NaCl (satd) salting out saturation Allow mixture to stand Discard aqueous (bottom) + solid NaHCO3 until no more effervescence to remove water + anhydrous CaCl3 to further remove water +boiling chips aid boiling. Indirectly increase temperature Perform distillation Collect in ice bath First drop signifies the experimental boiling point of the product EXPERIMENT 7 ALCOHOLS, PHENOLS, ETHERS 1.Lucas TestModified Sn1 mechanism oreagent is acidic, protonating OH group, forming a carbocation oZn2+ is a lewis acid (e- acceptor); makes alcohol a better living group oreagent is polar-ionic, favoring carbocation function false positive result: benzyl alcohol onot very soluble in Lucas reagent otest relies on solubility difference between alcohol and alkyl chloride only alcohols with 5 C or less can be reacted with Lucas reagent 2.Oxidation of Alcohols Neutral KMnO4 Oxidation is only possible for primary and secondary alcohols 1 alcohols carboxylic acid 2 alcohols ketone *Benzyl alcohol acts like 1 alcohols *Ethers inert to oxidation by KMnO4 and H2CrO4 3.Acidity of phenols opresence of electron withdrawing groups (EWGs) results to stability of conjugated base (phenoxide) o EWG, resonance, stability of phenoxide, acidity pH Phenol5 p-nitrophenol3 Picric acid1 4.Complexation of Phenols with FeCl3 -products depend on the conjugating group present Bright colors (characteristics of complexes) 5.Reaction of Phenol with Br2 oEAS electron aromatic substitution oTribromination due to e- rich benzene (e- donating OH group) 6.Oxidation of Phenols -Produces quinones unsaturated ketones EXPERIMENT 8 and 9 ALIPHATIC AND AROMATIC HYDROCARBONS and RELATIVE RATES OF ELECTROPHILIC AROMATIC SUBSTITUTION Saturated Aliphatic Hydrocarbons Hexane single bonds and C and H -Inert, insoluble in cold concentrated H2SO4 Unsaturated Aliphatic Hydrocarbons Limonene -Generally undergo addition reactions -Soluble in cold concentrated H2SO4 Aromatic Hydrocarbons Benzene -Generally undergo substitution -Insoluble in cold concentrated H2SO4 but soluble in fuming H2SO4 Electrophilic Aromatic Substitution *electrophilic should be very reactive *An EDG can facilitate EAS (it stabilizes cationic intermediate) 1.Cationic intermediate forms aromacity is temporarily lost stability EDG stabilizes the intermediate *presence of EDG *stable intermediate *rate of reaction EDG o-p directors (o-p position where the charge is) --OH, -NH, -NHR, -NR2 strong --OR, -NHCOR moderate -C6H5, R weakEWG m-directors --NO2, -NR2+, -CX3 strongly deactivating --CN, -COOH, -COOR, -CHO, -COR, CONH2, SO3H weakly deactivating Some EWG are o-p-directors --F, -Cl, -Br, -I deactivating 2.Aromatic Bromination +Br2 in CH3COOH has polarizing effect; makes Br2 polar Performed in dark conditions to avoid other reactions involving bromine and to ensure only electrophilc aromatic substitution will take place Aniline > phenol > acetanilide > p-nitrophenol > benzene > chlorobenzene 3.Effect of solvent -Solvent should be a Lewis acid (AlCl3/FeCl3) or a polarizing solvent Unsaturated Aliphatic Hydrocarbons Distillation purification technique used for liquid mixtures Simple distillation used for separation of liquids whose boiling point differ greatlySteam distillation used for separation of liquids that are heat sensitive Tert-butyl chlorideWhite and orange positive for benzene Friedel-crafts alkylation Test for aromatic ring In the experiment Bromine in light conditions Hexane and limonene positive results -Alkanes -Rate depends on stability of free radical intermediate Benzylic acid > 3 > 2 > 1 > methyl BrBr 2Br initiation H3CH + Br CH3 + HBr propagation BrBr + CH3 CH3Br + Br propagation CH3 + CH3 CH3CH3 termination BrBr Br2 termination Br + CH3 CH3Br termination *limonene contains alkane group as well Br2 in dark Test for unsaturation Electrophilic addition Does not work in aromatic because they are stable Beyers Test (inconclusive test) Test for unsaturation Oxidation Combustion Flame test Alkane: 2 C6H14 + 19 O2 12 CO2 + 7 H2O Alkene: C10H16 + 14 O2 8 C + CO + CO2 + 8 H2O Aromatic: C6H6 + 3 O2 3 C + CO + CO2 + 3 H2O