Concept explainers
Interpretation:
The structure of the given compound and the mechanism of the given reaction are to be determined.
Concept introduction:
To determine the actual structure of organic compounds, IR spectroscopy (Infrared spectroscopy) is an invaluable tool. The use of
Transesterification is a process in which the R group of an ester is exchanged with an R group of an alcohol. This process takes place in the presence of a base catalyst or an acid catalyst.
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Organic Chemistry
- Gamma(y)-amino butyric acid (GABA) is a neurotransmitter (a chemical that is used to send signals from one neuron to another) of the mammalian central nervous system. In order to understand how GABA works, conformationally restricted analogues, such as compound 1, have been made. During a synthesis of compound 1, compound 2 was subjected to allylic bromination using NBS and a radical initiator (AIBN) instead of light (Aust. J. Chem. 1981, 34, 2231-2236). H₂N. CH3 GABA CO₂H CH3 dddd CH3 H₂N Modify the structures given below to draw all eight possible allylic bromides that can be formed when compound 2 undergoes allylic bromination, considering all possible regiochemical and stereochemical outcomes. You can use the single bond tool to add/remove pi bonds. CH3 CO₂H CH3 solddd CH3 CH3 2 CH₂ CO₂Etarrow_forwardAn amine of unknown structure contains one nitrogen and nine carbon atoms. The 13C-NMR spectrum shows only five signals, all between 20 and 60 ppm. Three cycles of Hofmann elimination sequence [(1) CH3I; (2) Ag2O, H3O; (3) heat] give trimethylamine and 1,4,8-nonatriene. Propose a structural formula for the amine.arrow_forwardFollowing is a synthesis for toremifene, a nonsteroidal estrogen antagonist whose structure is closely related to that of tamoxifen. (a) This synthesis makes use of two blocking groups, the benzyl (Bn) group and the tetrahydropyranyl (THP) group. Draw a structural formula of each group and describe the experimental conditions under which it is attached and removed. (b) Discuss the chemical logic behind the use of each blocking group in this synthesis. (c) Propose a mechanism for the conversion of D to E. (d) Propose a mechanism for the conversion of F to toremifene. (e) Is toremifene chiral? If so, which of the possible stereoisomers are formed in this synthesis?arrow_forward
- The following sequence of steps converts (R)-2-octanol to (S)-2-octanol. Propose structural formulas for intermediates A and B, specify the configuration of each, and account for the inversion of configuration in this sequence.arrow_forwardThe base-promoted rearrangement of an -haloketone to a carboxylic acid, known as the Favorskii rearrangement, is illustrated by the conversion of 2-chlorocyclohexanone to cyclopentanecarboxylic acid. It is proposed that NaOH first converts the a-haloketone to the substituted cyclopropanone shown in brackets and then to the sodium salt of cyclopentanecarboxylic acid. (a) Propose a mechanism for base-promoted conversion of 2-chlorocyclohexanone to the proposed intermediate. (b) Propose a mechanism for base-promoted conversion of the proposed intermediate to sodium cyclopentanecarboxylate.arrow_forwardc) Label (if possible) the structure(s) in part (b) as either Z or E double bond isomers. Recently, the Gademann research group from the University of Zurich, completed the synthesis of (+)-Peyssonnosol, a complex natural product (shown below on the left) which contains seven stereocenters. Briefly describe what the "(±)" symbol in front of the synthesized natural product name means. Me, Ме .Me Me HO... Me ... Me Synthesized (±)-Peyssonnosol Starting Materials Used in Synthesisarrow_forward
- Q5:- 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_forwardIs esmolol chiral? If so, which of the possible stereoisomers are formed in this synthesis?arrow_forward4. Here’s a figure-it-out mechanism, resulting in the formation of p-aminophenol from an aromatic hydroxylamine. Would you expect either ortho- or meta-aminophenol to form in competition? Why or why not? H H;0* H -N НО H2O ОН H 5. (a) The triaryl hydroxylamine hydrolyzes in acid to form two products: one compound containing two aromatic rings and one with a single aromatic ring. First, draw the two products and the mechanism of their formation in acidic water (this is another "figure it out" mechanism). Ph H;O* Ph—С—N H,0 Ph ОН (b) Suppose one of the aryl rings had a t-donating group (-OCH3) and the other had a n- withdrawing group (-NO2), both in the para position. Where would the substituents end up in the products (draw them)? Why? Do you suspect this reaction is under kinetic control or thermodynamic control, or both/either?arrow_forward
- When acetonitrile is treated with concentrated sulfuric acid and tert-butanol, followed by water, a product is formed whose 'H NMR spectrum exhibits the following three signals: singlet, 1.3 ppm, 9 H; singlet, 2.0 ppm, 3 H; and broad singlet, 8.2 ppm, 1 H. Its IR spectrum exhibits one broad absorption of medium intensity between 3300 and 3500 cm-1, and a narrow, intense absorption near 1650 cm¯1. A key intermediate is shown. Draw the structure of the product, and draw the complete, detailed mechanism for the reaction. CH3 CH3 H2SO4 (conc) H2O ? + H3C H3C H3C-C=Ñ-c `CH3 CH3 HOarrow_forwardD, E,Farrow_forwardGabapentin, an anticonvulsant used in the treatment of epilepsy, is structurally related to the neurotransmitter 4-aminobutanoic acid (GABA). -NH2 -NH, B -СООН COOH Gabapentin 4-Aminobutanoic acid (y-Aminobutyric acid, GABA) Gabapentin was designed specifically to be more lipophilic than GABA and therefore more likely to cross the blood-brain barrier, the lipidlike protective membrane that sur- rounds the capillary system in the brain and prevents hydrophilic (water-loving) com- pounds from entering the brain by passive diffusion. Given the following retrosynthetic analysis, propose a synthesis for gabapentin. -NH, -NH2 CN COOH -COOEt COOEt Gabapentin COOEt COOE. O + COOEt COOEt Cyclohexanone Diethyl malonatearrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningIntroduction to General, Organic and BiochemistryChemistryISBN:9781285869759Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar TorresPublisher:Cengage Learning