CH3 CH3 PBr3 он Primary and secondary alcohols can be converted to alkyl bromides via treatment with PBr3. The reaction proceeds via an Sy2 mechanism with inversion of configuration at the chiral carbon. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions :Br: CH2 :Br СНЗ Br: Br: Br: он

(R)-Pulegone, readily available from pennyroyal oil, is an important enantiopure building block for organic syntheses. Propose a mechanism for each step in this transformation of pulegone.

When a primary alcohol is treated with p-toluenesulfonyl chloride at room temperature in the presence of an organic base such as pyridine, a tosylate is formed. When the same reaction is carried out at higher temperature, an alkyl chloride is often formed. Explain.

The Baylis–Hillman reaction is a DABCO (1,4-diazabicyclo[2.2.2]octane) catalyzed reaction of an a,b-unsaturated carbonyl compound with an aldehyde toform an allylic alcohol. Propose a mechanism for the reaction. (Hint: DABCO serves as both a nucleophile and as a base in the reaction.)

Secondary alcohols are often dehydrated in an E2 reaction to give an alkene. Elimination follows Zaitsev's rule to give the more substituted alkene as the major product. Since the reaction occurs via an E2 mechanism, there is no risk of rearrangement of the carbon skeleton as could possibly occur if the elimination occurred via an E1 mechanism with a carbocation intermediate.Draw curved arrows to show the movement of electrons in this step of the mechanism.

If dehydration of 2-methylcyclohexanol were to occur under an E2 mechanism, draw the chair conformations of 2-methylcyclohexanol that would be necessary for the reaction to occur. 2-methylcyclohexanol is sold as a mixture of cis and trans isomers

) Which of the following scientific statements are true and which           are false? 1- [     ] E1 describes an elimination reaction in which the rate-determining step                does not involve the base.   2- [     ] Rate of formation of carbocations follow the order 3˚ > 2˚> 1˚> CH3+   3- [     ] Cyclohexanol is oxidized to ketone using Jone's reagent.   4- [     ] Symmetric ethers are generally synthesized by dehydration of                                 alcohols. 5- [       ] The SN2 reaction occurs with inversion of configuration.

Alcohols react with sulfonyl chlorides to form sulfonate esters. Only the O-H bond of the alcohol is broken in the reaction, and so no inversion of configuration occurs. The resulting sulfonate esters are reactive in SN1 and SN2 reactions since the sulfonate group is a very weak base and is therefore a good leaving group.Draw curved arrows to show the movement of electrons in this step of the mechanism.

In the synthesis of 2-methyl-pentan-2-ol from pentan-2-one, the source of the nucleophile in nucleophilic attack on the carbonyl carbon is  __________.     -C≡N     CH3MgBr     -C≡CCH3     NaOCH3     KMnO4

Oxidation of cholesterol converts the alcohol to a ketone. Under acidic or basic oxidationconditions, the C“C double bond migrates to the more stable, conjugated position. BeforeIR and NMR spectroscopy, chemists watched the UV spectrum of the reaction mixture tofollow the oxidation. Describe how the UV spectrum of the conjugated product, cholest-4-en-3-one, differs from that of cholesterol