FA23 CHEM 225 Exp9 HANDOUT_E2 Rxn_001 (1)

Reaction of propene (above) with HBr might, in principle, lead to a mixture of two alkyl bromide addition products. Name these two alkyl bromides.

Reaction of 2-methyl-2-butene (above) with HBr might, in principle, lead to a mixture of two alkyl bromide addition products. Draw these two alkyl bromides.

OH NaOH H3C CH3 H3C CH3 Alkyl halides undergo nucleophilic substitution and elimination reactions. When the kinetics of the reaction are measured, if the rate of the reaction is found to be dependent only upon the concentration of the alkyl halide the reaction is first order. The substitution reaction is thus termed Sy1, and the elimination reaction is termed E1. These reactions are unimolecular and occur in two steps. The first step is rate-limiting and involves the loss of the leaving group to form a carbocation. In the second, fast, step the nucleophile adds to the carbocation in the SN1 reaction or elimination occurs to give an alkene in the E1 reaction. Because the carbocation is planar, the nucleophile can add to either face and therefore racemization is usually observed although solvent effects can influence this somewhat. E1 elimination follows Zaitsev's rule and typically yields the most substituted alkene as the major product. Conditions which favor the Sy1/E1 pathway include…

[Review Topics] [References] HO pyridine 1. SOCIl, + sO2 + H. Aqueous acetone H3C H20 H3C HBr 2. Br H OH optically active racemic f = SN1 Nucleophilic substitution g = SN2 Nucleophilic substitution a = Proton transfer d = E1 Elimination b = Lewis acid/base e = E2 Elimination c = Electrophilic addition The rections above involve synthesis or reactions of alcohols and ethers. Identify the mechanism by which they proceed from among the mechanisms listed. Use the letters a - g for your answers. 1. 2.

1. You are planning to carry out a reaction between butyne CH3CH₂C=CH, and sodium methoxide, CH3ONa. You also need to choose an appropriate solvent for the reaction. Would H₂O be an appropriate solvent? Explain your rationale.

CH3 CH3 Br- Br2 .CH3 CH2Cl2 CH3 H3C H3C Br Electrophilic addition of bromine, Brɔ, to alkenes yields a 1,2-dibromoalkane. The reaction proceeds through a cyclic intermediate known as a bromonium ion. The reaction occurs in an anhydrous solvent such as CH,Cl,. In the second step of the reaction, bromide is the nucleophile and attacks at one of the carbons of the bromonium ion to yield the product. Due to steric clashes, the bromide ion always attacks the carbon from the opposite face of the bromonium ion so that a product with anti stereochemistry is formed. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions CH3 CH3 CH3 CH3 H3C H3C :Br: :Br:

2. Show a reaction sequence to convert oil of wintergreen (methyl salicylate) into Aspirin (acetyl salicylic acid). This is a two-step sequence. You must show the structures for the intermediate product and the final product, along with the reagents/reaction conditions. OH

Compare the two reactions shown below. excess LICH,CH3 excess LICH,CH3 Both electrophiles, an ester and a ketone, are reacted with an excess amount of LICH2CH2. Which reaction will result in the formation of a product with the molecular formula C9H200 and why? O A: Only the reaction with the ester. LICH2CH3 results in an addition mechanism with both starting materials. However, the product from the ketone reaction contains fewer than 9 carbons. O B. Only the reaction with the ketone. LICH2CH3 results in an addition mechanism with both starting materials. However, the product from the ester reaction contains two oxygen atoms. O C. Both reactions. LICH2CH3 results in an addition mechanism with the ketone. However, the ester goes through a SNAC mechanism because it contains a leaving group, which allows two equivalents of LICH2CH3 to attack. O D. Neither reaction. LICH2CH3 results in a SNAC mechanism with both starting materials. Both products contain more than 9 carbons.

i need help drawing the product

4. Synthesize the following compound. You may use benzene, acetylene, ethanol and any inorganic reagents. O₂N

Acyl transfer (nucleophilic substitution at carbonyl) reactions proceed in two stages via a "tetrahedral intermediate." Draw the tetrahedral intermediate as it is first formed in the following reaction. CI H₂N OH • You do not have to consider stereochemistry. • Include all valence lone pairs in your answer. • Do not include counter-ions, e.g., Na+, I, in your answer. • In cases where there is more than one answer, just draw one. Sn [F

10) Synthesis: Make the following products from a suitable cyclic alkene starting material. Look at the functional group PATTERN present in the molecule, including stereochemistry. Br CH3 Br CH3

Select the reagent that you would use to convert an alkene to a Markovnikov (more substituted) alcohol without possibility of carbocation rearrangement. o H2SO4, H2O OBH3-THF, then H2O2, H2O, NaOH Hg(OAc)2, H2O, then NaBH4 o OsO4, TBHP, H2O

Acyl transfer (nucleophilic substitution at carbonyl) reactions proceed in two stages via a "tetrahedral intermediate." Draw the tetrahedral intermediate as it is first formed in the following reaction. CI + H₂N • You do not have to consider stereochemistry. • Include all valence lone pairs in your answer. OH • Do not include counter-ions, e.g., Na+, I¯, in your answer. • In cases where there is more than one answer, just draw one.

Consider the reaction below to answer the following questions. When dichlorocarbene is generated in the presence of an alkene, a dichlorocyclopropane is formed. Cl. CL CH₂ ( H₂C H C=C H + CHCl3 KOH H₂C--- CH3 H H Write the complete stepwise mechanism for the formation of dichlorocarbene, :CCl₂. Show all intermediate structures and show all electron flow with arrows.

Alcohols are acidic in nature. Therefore, a strong base can abstract the acidic hydrogen atom of the alcohol in a process known as deprotonation. The alcohol forms an alkoxide ion by losing the proton attached to the oxygen atom of the hydroxyl ( -OH) group. The alkoxide formed can act as a base or a nucleophile depending on the substrate and reaction conditions. However, not all bases can abstract the acidic proton of alcohols and not all alcohols easily lose the proton. Deprotonation depends on the strength of the base and the acidity of the alcohol. Strong bases, such as NaNH2, can easily abstract a proton from almost all alcohols. Likewise, more acidic alcohols lose a proton more easily. Determine which of the following reactions would undergo deprotonation based on the strength of the base and the acidity of the alcohol. Check all that apply. ► View Available Hint(s) CH3CH,OH + NH3 →CH,CH,O-NH CH3 CH3 H3C-C-H+NH3 → H3 C-C-H OH O-NH CH3CH2OH + NaNH, → CH3CH,O-Na* + NH3 CHC12 Cl₂…

CCH H20, H2SO4 H9SO4 CH3 Alkynes do not react directly with aqueous acid as do alkenes, but will do so in the presence of mercury(II) sulfate as a Lewis acid catalyst. The reaction occurs with Markovnikov regiochemistry, so the OH group adds to the more highly substituted carbon and the H adds to the less highly substituted carbon. The initial product of the reaction is a vinyl alcohol, also called an enol. The enol immediately rearranges to a more stable ketone via tautomerization. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions Hjö: -CH3 -CH3 H3O*

Acyl transfer (nucleophilic substitution at carbonyl) reactions proceed in two stages via a "tetrahedral intermediate." Draw the tetrahedral intermediate as it is first formed in the following reaction. 0 OH CI + H₂N • You do not have to consider stereochemistry. • Include all valence lone pairs in your answer. • Do not include counter-ions, e.g., Na+, I, in your answer. In cases where there is more than one answer, just draw one. A ChemDoodle Activate Windows

5 & 6

4. Dissolvable sutures are often used in medicine and dentistry so that additional surgeries don't need to be done to remove the stitches. Two examples of dissolvable sutures are: fart CH2 -CH2 Dexon® and -CH2 -CH2 -CH2 CH, -CH2 PDS® Using the organic chemistry you have learned so far, propose a mechanism for how they dissolve.

Draw the line-angle formula of the enol formed in the following alkyne hydration reaction and then draw the structural formula of the carbonyl compound with which this enol is in equilibrium. -C=CH 1. (sia)2BH 2. NaOH/H₂O₂ an enol carbonyl compound • You do not have to consider stereochemistry. • Draw both the enol and the carbonyl forms. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate structures using the sign from the drop-down menu. ChemDoodleⓇ <

H NH₂ ཡིནྣཾ ༥ ཨ ཨནྡྷ༥ ༠ ཨི་ཝཱ, ཙ ཨ་ར༩ H NH3+ the acidity of the amine ion drives the reaction to shift toward the conjugate base of the carboxylic acid product. the resulting carboxylic acid ion is a weaker base than an acetate ion. O aldehydes are more reactive toward nucleophiles than ketones. Onucleophilic attack occurs preferentially at the less hindered carbon of the formyl group.

МЕСНANISMS 1,2-epoxy-1-methylcyclopentane undergoes both acid-catalyzed and base-catalyzed opening of the epoxide ring to form two different products. > Using ethanol as the solvent and an appropriate acid, show the steps in the acid catalyzed mechanism, writing structures for all products of the steps. Circle the major product(s). > Using ethanol as the solvent and an appropriate base, show the steps in the base- catalyzed mechanism, writing structures for all products of the steps. Circle the major product(s). 1,2-epoxy-1-methylcyclopentane CH3

In SN2 reactions of haloalkanes, the order of reactivity is RI>RBr>RCl>RF. Alkyl iodides are considerably more reactive than alkyl fluorides, often by factors as great as 106. All 1-halo-2,4-dinitrobenzenes, however, react at approximately the same rate in nucleophilic aromatic substitutions. Account for this difference in relative reactivities.