chemistry - organic chemistry reaction scheme

Download chemistry - organic chemistry reaction scheme

Post on 11-Apr-2015

16.908 views

Category:

Documents

7 download

Embed Size (px)

TRANSCRIPT

<p>ORGANIC CHEMISTRY REACTION SCHEME AN OVERVIEW ALKANESPreparation of Alkanes 1. Hydrogenation of Alkenes CnH2n H2 + Ni, Pd or Pt CnH2n+2 2. Reduction of Alkyl Halides a. Hydrolysis of Grignard Reagent RX + Mg dry ethyl ether RMgX water RH + Mg(OH)X *Note: RMgX is the Grignard reagent, alkylmagnesium halide. The alkyl group is covalently bonded to magnesium; and magnesium-halogen bond is ionic ie. [R:Mg]+[X]. In the second step of the reaction, it is a displacement reaction in which water (the stronger acid) displacing the weaker acid (RH) from its salt (RMgX).</p> <p>b. Reduction by Metal and Acid RX Zn + H RH + Zn2+ + X Reactions of Alkanes 1. Halogenation [Free Radical Substitution] CnH2n+1H + X2 heat, or UV CnH2n+1X + HX 2. Combustion CnH2n+2 + excess O2 heat nCO2 + (n+1)H2O 3. Pyrolysis Cracking 400-600 C alkane with or w/o catalyst H2 + smaller alkanes + alkenes+</p> <p>ALKENESPreparation of Alkenes 1. Dehydrohalogenation of Alkyl Halides H H</p> <p>Halcoholic KOH reflux</p> <p>H C + H K X + H 2O</p> <p>H</p> <p>C H</p> <p>C X</p> <p>H OH </p> <p>H</p> <p>C</p> <p>2. Dehydration of Alcohols H H</p> <p>H H excess conc H2 SO4 , 170 C or Al2 O3 , 400 C or H3PO4 , 200-250 C</p> <p>H C H+ H 2O</p> <p>H</p> <p>C H</p> <p>C OH</p> <p> H</p> <p>C</p> <p>3. Dehalogenation of Vicinal Dihalides H H</p> <p>HZn H H</p> <p>H C H+ Z n X2</p> <p>H</p> <p>C X</p> <p>C X</p> <p>C</p> <p>Reactions of Alkenes 1. Addition of Hydrogen. Catalytic Hydrogenation H + Ni, Pd or Pt CnH2n 2 Heat CnH2n+2</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>1</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>2. Addition of Halogens [Electrophilic Addition using bromine/ethene] H H H H</p> <p>H</p> <p>C</p> <p>C</p> <p>H dark, room/CCl4 X2 temperature </p> <p>H</p> <p>C X</p> <p>C X</p> <p>H</p> <p>3. Addition of Aqueous Halogen. Formation of Halohydrin H H H</p> <p>H C OH H H C H H H C OH H H C OH H+ H 2S O4</p> <p>H</p> <p>C</p> <p>C</p> <p>H X2 /H2O H Dark, room temp</p> <p>C X</p> <p>H+ H X</p> <p>4. Addition of Hydrogen Halides H</p> <p>H CHX H H</p> <p>H</p> <p>C</p> <p>C X</p> <p>H</p> <p>5. Addition of Water. Hydration a) Industrial Method H H</p> <p>H</p> <p>C</p> <p>C</p> <p>H</p> <p>H O(g) conc2H3PO4 300C, 60atm</p> <p>H</p> <p>C H</p> <p>H</p> <p>b) Laboratory Method H H</p> <p>H H C H</p> <p>H C HH2 O, heat H (hydrolysis)</p> <p>H</p> <p>C</p> <p>C</p> <p>H</p> <p> conccoldSO4 H2</p> <p>C H</p> <p>OS O 3 H</p> <p>6. Oxidation a) Cold, alkaline KMnO4 Solution H H</p> <p>Halkaline KMnO4 H cold</p> <p>H C OH H H</p> <p>H</p> <p>C</p> <p>C</p> <p>H</p> <p>C OH</p> <p>b) Hot, acidic KMnO4 Solution H H</p> <p>H</p> <p>H</p> <p>C</p> <p>C</p> <p>H</p> <p>MnO4 /H2 SO4 H hot</p> <p>C</p> <p>O</p> <p>+</p> <p>O</p> <p>C</p> <p>H</p> <p>*Note: Terminal carbons will be oxidized into carbon dioxide. *Note: Under such oxidizing conditions, the aldehydes will be oxidized to carboxylic acid very quickly. To extract the aldehyde only, we must use immediate distillation.</p> <p>7. Combustion</p> <p>ARENESReactions of Benzenes 1. Nitration [Electrophilic Substitution in mononitration of benzene] NO2conc. HNO3 conc. H2 SO4</p> <p>55oC</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>2</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>2. SulphonationH2 SO 4 ( l ) reflux</p> <p>OSO 2H + H 2O</p> <p>3. Halogenation</p> <p>X + X2cold, dark FeX3 , or AlX3</p> <p>+ HX</p> <p>Or Fe 4. Friedel-Crafts Alkylation</p> <p>R + RXFeX3 , or AlX3 Lewis Acid</p> <p>+ HX</p> <p>5. Friedel-Crafts Acylation</p> <p>CORNote: acyl group</p> <p>+ R C O C l / [(R C O ) 2O ]</p> <p>FeX3 , or AlX3</p> <p>+ HXR C</p> <p>O</p> <p>H</p> <p>6. Hydrogenation</p> <p>+ 3H</p> <p>2</p> <p>Ni 150C</p> <p>Preparation of Alkylbenzenes 1. Attachment of Alkyl Group. Friedal-Crafts Alkylation</p> <p>R + HX</p> <p>+ RX</p> <p>FeX3 , or AlX3 Lewis Acid</p> <p>2. Conversion of side chain R</p> <p>H C OZn(Hg), HCl, heat or N2H4 , base, heat</p> <p>H RN2 + H X + H2 O</p> <p>COr H2/Pd, ethanol</p> <p>*Note: This is known as the Clemmensen or Wolff-Kishner Reduction</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>3</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>Reactions of Alkylbenzenes 1. Hydrogenation</p> <p>R + 3H2Ni, Pt, Pd 150C</p> <p>R</p> <p>2. Oxidation a. Mild Oxidation</p> <p>RMnO2 oxidation</p> <p>CHO</p> <p>b. Strong Oxidation</p> <p>RMnO4 /H2 SO4 or acidified K 2 Cr2 O7</p> <p>COOH w h ite c r y s ta ls</p> <p>3. Free Radical Aliphatic Halogenation RCH3 X2 UV, light or heat</p> <p>RCH2X</p> <p>*Note: Reaction above is only a generic reaction. Actual position of the halogen is dependent on the stability of the carbocation intermediate.</p> <p>4. Electrophillic Aromatic Halogenation by Electrophillic Addition R R</p> <p>R</p> <p>XX2 FeX3 , FeX5</p> <p>+</p> <p>X5. Electrophillic Aromatic Nitration by Electrophillic Addition R R</p> <p>R NO2</p> <p>conc HNO3 conc H2 SO4</p> <p>+</p> <p>30 C</p> <p>o</p> <p>NO26. Electrophillic Aromatic Friedal-Crafts Alkylation by Electrophillic Addition R R R</p> <p>R1R1X AlX3</p> <p>+</p> <p>R1http://education.helixated.com An Open Source Education Project</p> <p>4</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>7. Electrophillic Aromatic Sulphonation by Electrophillic Addition R R</p> <p>R</p> <p>OSO 2HH2 SO4 ( l ) </p> <p>+</p> <p>OSO 2H8. Electrophillic Aromatic Friedal-Crafts Acylation by Electrophillic Addition R R</p> <p>R COR1</p> <p>+ R 1C O C l / [(R 1C O )2O ]</p> <p>FeX3 , or AlX3 </p> <p>+</p> <p>COR1Alkylbenzenes clearly offers two main areas to attack by halogens: the ring and the side chain. We can control the position of the attack simply by choosing the proper reaction conditions. Refer to Appendix for more details.</p> <p>HALOGEN DERIVATIVESPreparation of Halogenoalkanes 1. Substitution in Alcohols a. Using HX (suitable for 3 alcohols) dry HX, ZnX2 (catalyst) ROH RX + H2O Reflux b. Using PX3/PX5 (suitable for 1, 2 alcohols) PX3 /PX 5 ROH RX + POX3 + HX Reflux c. Using SOCl2 (sulphonyl chloride) SOCl2 , Pyridine(C5H5N) ROH RCl + SO2 + HCl Reflux*Note: This is the best method because it is very clean. SO2 can be bubbled off and HCl, being an acid, will react with pyridine.</p> <p>2. Electrophillic Addition to Alkenes a) Addition of Hydrogen Halides H H</p> <p>HHX H H</p> <p>H C H H H C X H H</p> <p>H</p> <p>C</p> <p>C</p> <p>C X</p> <p>b) Addition of Halogens H H</p> <p>H</p> <p>C</p> <p>C</p> <p>X2 /CCl4 H dark, room temperature</p> <p>H</p> <p>C X</p> <p>3. Free Radical Substitution of Alkanes heat, or UV CnH2n+1H + X2 CnH2n+1X + HX </p> <p>http://education.helixated.com An Open Source Education Project</p> <p>5</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>Reactions of Halogenoalkanes 1. Alkaline Hydrolysis of Alcohols [Nucleophilic Substitution] aqueous KOH RX + OH reflux ROH + X*Note: Mechanism is SN2 for 1 halogenoalkane and SN1 for 3 halogenoalkane</p> <p>2. Nitrile Synthesisaqueous ethanol RX + NaCN reflux RCN + NaBr</p> <p>*Note: Nitriles are useful because they can be used to synthesize 1o amines and carboxylic acids. Reduction to Amine: LiAlH4 , dry ether RCN or 2H2 , Ni, heat RCH2NH2 Acidic Hydrolysis:HCl ( aq ) RCN reflux RCOOH + NH4+</p> <p>Basic Hydrolysis:NaOH ( aq ) RCN reflux RCOONa+ + NH3</p> <p>3. Formation of Aminesethanol, reflux NH3 RX + excess conc NH3 sealed tube [H3N---R---X] RNH2 + NH4+X+ </p> <p>*Note: NH3 acts as the nucleophile and the base. *Note: In the presence of excess RX, there will be polyalkylation of the halogenoalkane and 1, 2, 3 and even 4 ammonium salt will be formed. NH3 RX RNH2 RX R2NH RX R3N RX R4N+XConc 4. Williamson Synthesis (Formation of Ether) H SO , 140 C RX + R'O Na+ ROR' + NaX2 4 o</p> <p>*Note: The sodium or potassium alkoxide (anion of alcohol) is prepared by dissolving sodium and potassium in appropriate alcohol. ROH + Na RONa+ + H2</p> <p>5. Dehydrohalogenation (Elimination) H H</p> <p>H C</p> <p>H C H + K X + H 2O</p> <p>H</p> <p>C H</p> <p>C X</p> <p> alcoholic KOH H H + OH (aq ) reflux</p> <p>Preparation of Halogenoarenes (Aryl Halides) 1. Electrophilic Aromatic Halogenation by Substitution</p> <p>X + HX</p> <p>+ X</p> <p>2</p> <p>cold, dark FeX3 , or AlX3</p> <p>Reactions of Halogenoarenes 1. Industrial Hydrolysis (Replacement of Halogen Atom, difficult due to strong CX bond) + X O Na2NaOH 350C, 150atm</p> <p>+ N aX</p> <p>+ H 2O</p> <p>+ O NaH ( aq ) +</p> <p>-</p> <p>OH + Na+</p> <p>2. Williamson Synthesis (Formation of Ether) RX + ArONa+ ROAr + NaXConc H2SO4, 140oC http://education.helixated.com An Open Source Education Project</p> <p>6</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>HYDROXY COMPOUNDSPreparation of Alcohols 1. Alkene Hydration. Addition of Water. H H</p> <p>H C H</p> <p>H C HH2 O, heat H (hydrolysis)</p> <p>H C H</p> <p>H C OH H+ H 2S O4</p> <p>H</p> <p>C</p> <p>C</p> <p>H</p> <p>conc H2 SO4 cold</p> <p>H</p> <p>OS O 3 H</p> <p>2. Alkaline Hydrolysis of Halogenoalkanes aqueous KOH RX + OH ROH + X reflux 3. Reduction of Carboxylic Acids, Aldehydes and Ketones a. Carboxylic Acids and Aldehydes are reduced to their primary alcohols. H R</p> <p>C HO R</p> <p>O</p> <p>+</p> <p>4 [H ]</p> <p>1. LiAlH4 (ethoxyethane), reflux 2.H /H2 0 or H2 , Ni</p> <p>+</p> <p>R</p> <p>C H</p> <p>OH</p> <p>+ H 2O</p> <p>H C O</p> <p>+</p> <p>4 [H ]</p> <p>1. LiAlH4 (ethoxyethane), reflux 2.H /H2 0 or H2 , Ni</p> <p>+</p> <p>R</p> <p>C H R</p> <p>OH</p> <p>Hb. Ketones are reduced to their secondary alcohols. R</p> <p>C R1</p> <p>O</p> <p>+</p> <p>4 [H ]</p> <p>1. LiAlH4 (ethoxyethane), reflux 2.H /H2 0 or H2 , Ni</p> <p>+</p> <p>R1</p> <p>C H</p> <p>OH</p> <p>*Note: Lithium aluminium hydride (or Lithium tetrahydridoaluminate(III)), LiAlH4, is one of the few reagents that can reduce an acid to an alcohol; the initial product is an alkoxide which the alcohol is liberated by hydrolysis. The H ion acts as a nucleophile, and can attack the carbon atom of the carbonyl group. The intermediate then reacts with water to give the alcohol. OH R O H3C H3C H 2O C C O C H H H H H H Carboxylic Acid: 4RCOOH + 3LiAlH4 4H2 + 2LiAlO2 + (RCH2O)4AlLi H2O 4RCH2OH Ketones: 4R2C=O + LiAlH4 (R2CHO)4AlLi H2O 4R2CHOH + LiOH + Al(OH)3</p> <p>Reactions of Alcohols 1. Substitution in Alcohols a. Using HX (suitable for 3 alcohols) dry HX, ZnX2 (catalyst) ROH Reflux RX + H2O b. Using PX3/PX5 (suitable for 1, 2 alcohols) PX3 /PX ROH Reflux 5 RX + POX3 + HX c. Using SOCl2 (sulphonyl chloride) SOCl , Pyridine(C H N) ROH 2 Reflux 5 5 RCl + SO2 + HCl*Note: This is the best method because it is very clean. SO2 can be bubbled off and HCl, being an acid, will react with pyridine.</p> <p>2. Reaction with Sodium/Potassium H</p> <p>HSodium/Potassium H </p> <p>H</p> <p>C H</p> <p>O</p> <p>H</p> <p>C H</p> <p>O Na</p> <p>-</p> <p>+</p> <p>+</p> <p>1 H 2</p> <p>2</p> <p>*Note: Alcohols are too weak to react with hydroxides and carbonates. http://education.helixated.com An Open Source Education Project</p> <p>7</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>3. Oxidation to Carbonyl Compounds and Carboxylic Acids a. Primary Alcohols are oxidized to aldehydes first, then carboxylic acids. R R R OH K 2 Cr2 O7 /H2 SO4 K 2 Cr2 O7 /H2 SO4 C O C C immediate or KMnO4 /H2 SO4 distillation H H HO H*Note: MnO2 is also a milder oxidizing agent.</p> <p>O</p> <p>b. Secondary Alcohols are oxidized to ketones. R R OH K 2 Cr2 O7 /H2 SO4 C C or KMnO4 /H2 SO4 R1 R1 H c. Tertiary alcohols are not readily oxidized.</p> <p>O</p> <p>4. Dehydration to Alkenes a. Excess conc H2SO4 H H</p> <p>Hexcess conc H2 SO4 , 170 C H H or Al2 O3 , 400 C or H3PO4 , 200-250 C</p> <p>H C H+ H 2O</p> <p>H</p> <p>C H</p> <p>C OH</p> <p>C</p> <p>b. Excess alcohol 140 C RCH2OH + conc H2SO4 RCH2O CH2R excess alcohol 5. Esterification</p> <p>O O R1 conc H2SO4 heat</p> <p>R C OH</p> <p>+</p> <p>O H</p> <p>C R O</p> <p>R1</p> <p>+</p> <p>(can use acid or alkaline as catalyst)</p> <p>H 2O</p> <p>6. Acylation a. Acid Chloride</p> <p>Note: acyl group</p> <p>R</p> <p>C O</p> <p>Cl</p> <p>+</p> <p>R1</p> <p>OH</p> <p> room temperature</p> <p>R</p> <p>C O</p> <p>O</p> <p>R1</p> <p>+ HClR C</p> <p>O</p> <p>H</p> <p>b. Acid Anhydride</p> <p>R</p> <p>C O</p> <p>O</p> <p>C O</p> <p>R</p> <p>+ R1 OH</p> <p>room temperature </p> <p>R</p> <p>C O</p> <p>O</p> <p>R1</p> <p>+</p> <p>R</p> <p>C O</p> <p>OH</p> <p>7. Tri-Iodomethane (Iodoform) Formation*Note: Reaction is only positive for alcohol containing a methyl group and a hydrogen atom attached to the carbon at which the hydroxyl group is also attached.H R C CH3 OHI2 , NaOH ( aq ) warm</p> <p>H H C CH3 OH</p> <p>CHI3</p> <p>a. Step 1: Oxidation of Alcohol to the corresponding carbonyl compound by iodine.</p> <p>R</p> <p>CH CH3</p> <p>OH</p> <p>+</p> <p>I 2 + 2 HO</p> <p>-</p> <p>R</p> <p>C CH3</p> <p>O</p> <p>+ 2 H2 O</p> <p>+ 2 I</p> <p>-</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>8</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>b. Step 2: Further oxidation to carboxylate salt and formation of iodoform</p> <p>R</p> <p>C CH3c.</p> <p>O</p> <p>+ 3 I2 + 4 HO</p> <p>-</p> <p>R</p> <p>C O-</p> <p>O</p> <p>+ CHI3 + 3 I</p> <p>-</p> <p>+ 3 H 2O</p> <p>H C</p> <p>Overall Equation:</p> <p>R</p> <p>OH + 4 I 2 + 6 HO</p> <p>-</p> <p>R</p> <p>C O-</p> <p>O</p> <p>+ CHI3 + 5 I</p> <p>-</p> <p>+ 5 H 2O</p> <p>CH3Preparations of Phenols 1. Replacement of OH group in diazonium salts N</p> <p>O-</p> <p>NH2</p> <p>+ N O</p> <p>S O</p> <p>OH</p> <p>OH</p> <p> NaNO2 , H2 SO 4</p> <p>water, H , heat </p> <p>+</p> <p>Reactions of Phenols 1. Reaction with Reactive Metals (e.g. Na or Mg)</p> <p>OH</p> <p>O Na</p> <p>-</p> <p>+</p> <p>+</p> <p>Na</p> <p>+</p> <p>1 H 2 2</p> <p>2. Reaction with NaOH</p> <p>OH</p> <p>O Na</p> <p>-</p> <p>+</p> <p>+ NaOH*Note: Phenols have no reactions with carbonates</p> <p>+</p> <p>1 H O 2 2</p> <p>3. Esterifications</p> <p>OHNaOH </p> <p>O Na</p> <p>-</p> <p>+RCOCl </p> <p>O C R</p> <p>O</p> <p>*Note: Phenols do not react with carboxylic acids but their acid chlorides to form phenyl esters. *Note: Esterification is particularly effective in NaOH(aq) as the alkali first reacts with phenol to form phenoxide ion which is a stronger nucleophile than phenol.</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>9</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>4. Halogenation a. With bromine(aq)</p> <p>OH Br3Br2 ( aq ) </p> <p>OH</p> <p>Br</p> <p>+ 3HBr</p> <p>Br*Note: 2,4,6-tribromophenol is a white ppt.</p> <p>b. With bromine(CCl4) OHBr2 (CCl4 ) </p> <p>OH</p> <p>OH</p> <p>+Br Br</p> <p>5. Nitration a. With conc nitric acid</p> <p>OH O 2Nconc HNO3 </p> <p>OH NO2</p> <p>NO2b. With dilute nitric acid OHdil HNO3 </p> <p>OH</p> <p>OH</p> <p>+NO2 O 2N</p> <p>6. Reaction with FeCl3(aq)*Note: This is a test for phenol. Violet complex upon adding iron(III) chloride will confirm presence of phenol. Colour may vary depending on the substitution on the ring.3 --</p> <p>OHFe 3+</p> <p>O Fe6</p> <p>http://education.helixated.com An Open Source Education Project</p> <p>10</p> <p>nh05</p> <p>ORGANIC</p> <p>CHEMISTRY</p> <p>REACTION</p> <p>SCHEME</p> <p> AN</p> <p>OVERVIEW</p> <p>CARBONYL COMPOUNDSPreparation of Aldehydes 1. Oxidation of Primary Alcohols R OH K 2 Cr2 O7 /H2 SO4 C immediate distillation H H</p> <p>R C H O</p> <p>+</p> <p>H 2O</p> <p>Preparations of Ketones 1. Oxidation of Secondary Alcohols R R OH K 2 Cr2 O7 /H2 SO4 C C or KMnO4 /H2 SO4 R1 R1 H 2. Oxidative Cleavage of Alkenes R2 R3</p> <p>O</p> <p>+ H 2O</p> <p>R2MnO4 /H2 SO4 hot</p> <p>R3 + O O C R4</p> <p>C R1</p> <p>C R4</p> <p>C R1</p> <p>Reactions of Carbonyl Compounds 1. Addition of Cyanide. Cyanohydrin formation. [Nucleophilic Addition of Hydrogen Cyanide to Aldehyde and Ketone] H H H C HCN, small amount of base + CN H C CN </p> <p>O*Note: Cyanohydrins can be hydrolysed to form 2-hydroxy acids. Acidic HydrolysisR C OH R C OH H CNwater, HCl (aq) heat</p> <p>OH</p> <p>H</p> <p>COOH</p> <p>+ NH4Cl</p> <p>Basic HydrolysisH</p> <p>R C OH CNwater, NaOH ( aq ) H heat</p> <p>R C OH COO Na+</p> <p>+</p> <p>NH3</p> <p>*Note: Cyanohydrins can undergo reduction.R C OH R CNLiAlH4 in dry ether or H2 , Ni, heat</p> <p>H</p> <p>H</p> <p>C OH</p> <p>CH2NH2</p> <p>R2</p> <p>2. Reaction w...</p>

Recommended

View more >