* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Review sheet - Paws.wcu.edu.
Marcus theory wikipedia , lookup
Kinetic resolution wikipedia , lookup
Discodermolide wikipedia , lookup
Enantioselective synthesis wikipedia , lookup
Elias James Corey wikipedia , lookup
George S. Hammond wikipedia , lookup
Hofmann–Löffler reaction wikipedia , lookup
Tiffeneau–Demjanov rearrangement wikipedia , lookup
Physical organic chemistry wikipedia , lookup
1,3-Dipolar cycloaddition wikipedia , lookup
Stille reaction wikipedia , lookup
Ring-closing metathesis wikipedia , lookup
Bottromycin wikipedia , lookup
Wolff rearrangement wikipedia , lookup
Homoaromaticity wikipedia , lookup
Ene reaction wikipedia , lookup
Hydroformylation wikipedia , lookup
Petasis reaction wikipedia , lookup
Wolff–Kishner reduction wikipedia , lookup
Aromaticity wikipedia , lookup
Asymmetric induction wikipedia , lookup
Strychnine total synthesis wikipedia , lookup
Chemistry 242 Final Exam Summer 2010 The final exam for this course will be on Friday, Aug. 6. It will be on the material in Chapters 10 – 21, 24, and 25 that we have covered in class The following text section will be covered on the exam. (Bold indicates change from hourly exams.) Chapter 10: all except 10.9 Chapter 11: all except 1, 12 and 13 Chapter 13: sections 13.8 – 13.11 only Chapter 14: section 14.1 only Chapter 15: sections 2, 3, 5, 6, and 10 only Chapter 16: all except 16.8, 16.9 Chapter 17: all except 17.10, 17.11 Chapter 18: sections 1, 2, 3 Chapter 19: all except 9, 10, 12 – 15 Chapter 20: all except 20.5 Chapter 21: all except 21.8, 21.9 Chapter 24: sections 1 – 4 and 6 only Chapter 25: sections 1, 3, 5, 9, 10 only It is especially important to study and do the problems for the following sections: 10.4 10.5 10.7 11.4 11.5 11.11 18.3 13.8 13.9 13.11 14.1 15.3 15.5 16.1 16.5 16.6 17.4 to 17.7 17.6 19.4 19.8 19.11 20.6 21.2 21.3 21.6 24.6 25.10 Topics that may be covered on the final Names for functional groups covered this semester. Free radical halogenation of an alkane (ex: Cl2/uv light). Which radical is most stable? Allylic bromination of an alkene. Draw out resonance forms for the allylic radical. Oxidation and reduction in organic chemistry. Identify the nucleophile and electrophile in a reaction. Which compound is a better nucleophile? Give products for these elimination reactions (E1 or E2) or substitution reaction (SN1 or SN2). Given a molecular formula and NMR spectrum, determine the structure for a compound. 1 H NMR spectroscopy: chemical shift, integration, and the n+1 rule for splitting Find the degree of unsaturation for a given molecular formula. Draw out isomers for that formula. Draw out the NMR splitting pattern for the following structure. Which systems are conjugated? Which are aromatic? (4n+2 rule) For aromatic substitution reactions, does a substituent direct ortho/para or meta? Which of the groups on an aromatic ring is the most powerful director? Does a group activate or deactivate an aromatic ring? By induction or by resonance? How would you synthesize the following di- or trisubstituted benzene? Which compound is more acidic? Which is more basic? Which of the carboxylic acid derivatives is the most stable? Which is the most reactive? Preparation of carboxylic acid derivatives and their conversion to other derivatives. Protecting groups for alcohols (TMS-Cl) and aldehyde/ketones (acetal). Synthesis problems – know reactions needed to make an organic molecule from an alkane. Know the following electrophilic aromatic substitution reactions. Bromination (Br2/FeBr3) Chlorination (Cl2/FeCl3) HNO3/cat. H2SO4 (nitration) Sulfonation - fuming sulfuric acid (SO3/H2SO4) RC(=O)Cl / AlCl3 (Friedel-Crafts Acylation) R-X / AlCl3 (Friedel-Crafts Alkylation) Other aromatic topics Ph-NO2 Ph-NH2 (reduction/oxidation) Ph-CO-R Ph-CH2-R (reduction/oxidation) Sulfonate as a temporary blocking group Synthesis of disubstituted aromatic compounds, ortho, meta, and para NMR Chemical shift regions, coupling patterns, integration, equivalent protons (skip 13C NMR) Be able to determine a structure, using the 1H NMR spectrum and molecular formula! Reagents for Haloalkanes (X = F, Cl, Br, I) Cl2 or Br2 plus uv light – free radical addition to form a haloalkane SOCl2 and PBr3 (converts R-OH to R-X for 1° and 2° alcohols) HCl / HBr (R-OH to R-X for 3° alcohols) NBS (for allylic bromination) Alkene plus X2 or HX : addition to double bond (Markovnikov selectivity) Preparation of Alcohols Hydration of alkenes: acid-catalyzed addition of water (Markov.) or BH3/ox (Anti-Markov.) Reduction of carbonyl compounds: NaBH4 (ald/ketones), LiAlH4 (ald/ketones/acids/esters/amides) SN2 reaction: unhindered alkyl halide R-X reacts with OH– to form the alcohol R-OH **Addition of Grignards or R-Li to aldehydes, ketones, and esters: mechanism, limitations Reactions of Alcohols Deprotonation with strong base (NH2–, K metal) to form the alkoxide RO– Protection with Me3Si-Cl to form R-OTMS (silyl ether) Oxidation to carbonyl: PCC or CrO3 (know when to use which reagent) Conversion to R-X : HBr (dry, for 3° alcohols), PBr3, SOCl2 (for 1° and 2° alcohols) Elimination to alkenes: POCl3 (1° and 2°) or H2SO4 (for 3° alcohols) Aldehydes and Ketones Preparation: from oxidation of primary or secondary alcohols Addition of nucleophiles to the carbonyl carbon (Nu = H–, RLi, RMgX, CN–) Acetal formation and use of acetals as a protecting group Carboxylic Acids and Derivatives Reactivity of derivatives: acid chlorides most reactive, amides least reactive Hydrolysis of acid chlorides, anhydrides, esters, and amides to carboxylic acids Reduction of carbox. acid derivatives with LiAlH4; addition of Grignard reagents Preparation and reaction of carboxylic acids and their derivatives Carbohydrates Identify potential simple sugars. Classify as monosaccharide or disaccharide. Cyclic hemiacetal form for sugars. Two forms for glucose – alpha and beta The structure and properties of starch and cellulose. Know the following reaction mechanisms: SN1/SN2/E1/E2 reactions: SN2/E2 transition states and SN1/E1 intermediates Electrophilic aromatic substitution – draw out resonance structures for the cationic intermediate Acetal formation (acid catalyzed) Fisher esterification (acid catalyzed) Nucleophilic acyl substitution (up-down-out) Example: acid chloride + alcohol to give ester Synthesis of a target compound, starting from a hydrocarbon or other simple molecules. What do PCC, CrO3, SOCl2, PBr3, NaBH4, LiAlH4, POCl3, Mg, CO2, NBS, HCl, R-Li, t-butoxide do? Skip: 13C NMR, Wolff-Kishner, Wittig Reaction Reaction Summaries Substitution/Elimination Nucleophile - strength of a nucleophile increases when: adding a negative charge RO- stronger than ROH moving left on the periodic table NH2- stronger than OHmoving down the periodic table PH3 stronger than NH3 Bases - base strength increased by: addition of a negative charge RO- stronger than ROH moving left on the periodic table NH2- stronger than OHmoving up the periodic table NH3 stronger than PH3 Leaving Group - good leaving groups are –OTos, –I, –Br, –Cl, and any neutral fragment (H2O) poor leaving groups are –OH, –NH2, –OR, –CH3 Key Factors for Reaction Mechanisms SN2 Reactions – unhindered electrophile (1°, maybe 2° R-X, but NOT 3°), good nucleophile SN1 Reactions – stable carbocation (3°, allylic, benzylic), protic solvent (ROH or H2O), no strong base E2 Reactions – strong base and an H next door to the leaving group; t-butoxide will promote E2 E1 Reactions - stable carbocation (3° or allylic, benzylic), protic solvent (ROH or H2O), weak base Electrophilic Aromatic Substitution (EAS) Directing power of various benzene substituents: Group I (-OR, -NH2) Group II (-X, -alkyl) Group III (all meta directors) Summary of Benzene Substituents Activators: add electron density to aromatic ring, speed up the rate of EAS, direct ortho/para can add e- density by induction (-alkyl groups) can add e- density by resonance (-OH, -OR, -NR2, -Ph ) Deactivators: remove electron density from aromatic ring, reduce rate of EAS, direct meta can remove e- density by induction (-CF3, -N+R3, -SO3H, -NO2 ) can remove e- density by resonance (-NO2, -CN, -C(=O)-R carbonyl) Halogens: deactivators that are ortho/para directors Synthesis Tips Count carbons, and check the carbon skeleton. What carbon atoms must be added? To add carbons to a molecule, use Grignard plus carbonyl (most of the time). Starting w/ an alkane, free radical halogenation (X2/uv light) is the only option. To make an alkane, use catalytic hydrogenation of an alkene (H2/cat). Aldehydes and ketones are formed by oxidation of the corresponding alcohol. Use an alkene to get TWO carbons involved in a functional group. Convert between alcohols and alkyl halides using the proper reagent.