(a)
Interpretation:
The reaction of
Concept Introduction:
Bromination of a diol usually results in the formation of bromide compounds due to nucleophilic substitution reactions. Reactions like these usually follow a mechanism, which usually results in a change in the configuration of the molecule.
(b)
Interpretation:
A plausible mechanism for the formation of the cyclic ether by-product has to be determined along with the stereochemical justification of the molecule.
Concept Introduction:
Diols when undergoing nucleophilic substitution reactions, sometimes tend to undergo cyclization via intramolecular bonding to form a cyclic ether, under appropriate conditions. Depending upon the type of alcoholic group involved in the formation of the nucleophile, the stereochemical configuration of the product molecule varies.
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ORGANIC CHEMISTRY 2-SEMESTER-ACCESS
- H3C. H3C. CH3 nnc» XT :OH 2 CH₂OH HCI catalyst Aldehydes and ketones react reversibly with two equivalents of alcohol in the presence of an acid catalyst to give acetals. Alcohols are poor nucleophiles, and so protonation of the carbonyl oxygen is used to make the carbonyl carbon a stronger electrophile. Addition of the first equivalent of alcohol gives a hemiacetal, a hydroxyether. Addition of the second equivalent of alcohol is accompanied by loss of water to yield the product acetal. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions CH3 H3C CH3OH H3CQ OCH3 CH3 H3C. H HO: :OCH 3 CH3 46arrow_forwardSeveral sulfonylureas, a class of compounds containing RSO2NHCONHR, are useful drugs as orally active replacements for injected insulin in patients with adult-onset diabetes. These drugs decrease blood glucose concentrations by stimulating b cells of the pancreas to release insulin and by increasing the sensitivity of insulin receptors in peripheral tissues to insulin stimulation. Tolbutamide is synthesized by the reaction of the sodium salt of p-toluenesulfonamide and ethyl N-butylcarbamate . Propose a mechanism for this step.arrow_forwardH3C OH OH H+ CH3 Esters can be synthesized by an acid-catalyzed nucleophilic acyl substitution between an alcohol and a carboxylic acid; this process is called the Fischer esterification reaction. Because the alcohol oxygen is a poor nucleophile, the carbonyl carbon is made a better electrophile by protonation of the carbonyl oxygen. The steps of the synthesis are all reversible. The reaction is generally driven to completion by using an excess of the liquid alcohol as a solvent, or by distilling off the product as it forms. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions CIX 10-4 H₂O CH3 H₂O CH3arrow_forward
- Ph3P-CHCH3 H₂C H3C Aldehydes and ketones are converted into alkenes by means of a direct nucleophilic addition called the Wittig reaction. In the reaction, a triphenylphosphorine ylide, also called a phosphorane, adds to an aldehyde/ketone to give a four-membered cyclic intermediate called an oxaphosphetane. The oxaphosphetane is not isolated but instead spontaneously decomposes to release triphenylphosphine oxide and an alkene. CH3 00 + The ylide is formed by reaction of triphenylphosphine, a good nucleophile, with a primary alkyl halide in an SN2 reaction, followed by deprotonation of the carbon with a strong base, such as butyllithium. The carbonyl carbon and the carbon originally bonded to the halogen become the two carbons with the double bond in the product alkene X m CH3 The real value of the Wittig reaction lies in its ability to yield an alkene of predictable structure, as the C=C bond is precisely where the C=O bond was in the reactant and no isomers (other than E/Z isomers)…arrow_forwardClaisen condensation between diethyl phthalate and ethyl acetate followed by saponification, acidification, and decarboxylation forms a diketone, C9H6O2. Propose structural formulas for compounds A and B and the diketone.arrow_forwardOne frequently used method for preparing methyl esters is by reaction of carboxylic acids with diazomethane, CH2N2. The reaction occurs in two steps: (l) protonation of diazomethane by the carboxylic acid to yield methyldiazonium ion, CH3N2+, plus a carboxylate ion; and (2) reaction of the carboxylate ion with CH3N2+. (a) Draw two resonance structures of diazomethane, and account for step 1. (b) What kind of reaction occurs in step 2?arrow_forward
- Amines are converted into alkenes by a two-step process called Hofmann elimination. SN2 reaction of the amine with an excess of CH3I in the first step yields an intermediate that undergoes E2 reaction when treated with silver oxide as base. Pentylamine, for example, yields 1-pentene. Propose a structure for the intermediate, and explain why it readily undergoes elimination.arrow_forwardThe Zeisel method is an old analytical procedure for determining the number of methoxyl groups in a compound. A weighed amount of the compound is heated with concentrated HI, ether cleavage occurs, and the iodomethane product is distilled off and passed into an alcohol solution of AgNO3, where it reacts to form a precipitate of silver iodide. The Agl is then collected and weighed, and the percentage of methoxyl groups in the sample is thereby determined. For example, 1.06 g of vanillin, the material responsible for the characteristic odor of vanilla, yields 1.60 g of Agl. If vanillin has a molecular weight of 152, how many methoxyl groups does it contain?arrow_forwardShow how the reagent for Step 6 can be prepared from salicylic acid (2-hydroxybenzoic acid). Salicylic acid, the starting material for the synthesis of aspirin and a number of other pharmaceuticals, is readily available by the Kolbe carboxylation of phenolarrow_forward
- Ketones and aldehydes react with sodium acetylide (the sodium salt of acetylene) to give alcohols, as shown in the following example: R, OH 1. HC=C: Na* 2. Hзо C. R2 R2 HC Draw the structure of the major reaction product when the following compound reacts with sodium acetylide, assuming that the reaction takes preferentially from the Re face of the carbonyl group. Use the wedge/hash bond tools to indicate stereochemistry where it exists. You do not have to explicitly draw H atoms. If a group is achiral, do not use wedged or hashed bonds on it.arrow_forwardQ5:- Give structures and names of the principal organic reactants and products of the following reactions. a- pentinoic acid from butanol b- Preparation of acid anhydrides Q6:- Rank the following substances in order of increasing acidity , Justify your choice. benzoic acid, p-chlorobenzoic acid , 2,4-dichlorobenzoic acid , 2,4,6-trichlorobenzoic acidarrow_forwardDd.84.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning