Give a structure for an optically inactive compound $A$ $\left(\mathrm{C}_6 \mathrm{H}_{10} \mathrm{O}_4\right)$, that can be resolved into enantiomers and has the following NMR spectra: ${ }^{13} \mathrm{C}$ NMR: $\delta 13.5, \delta 41.2, \delta 177.9$ proton NMR: $\delta 1.13(6 H, \mathrm{~d}, J=7 \mathrm{~Hz}) ; \delta 2.65$ ( $2 H$, quintet, $J=7 \mathrm{~Hz}) ; \delta 9.9\left(2 \mathrm{H}\right.$, broad s, disappears after $\mathrm{D}_2 \mathrm{O}$ shake)

Give the structure of an isomer of compound A that has a different melting point than A and NMR spectra that are almost identical to those of A.

$\beta$-Imino carboxylic acids such as the one in Fig. decarboxylate very rapidly provided that the $\mathrm{pH}$ is neither too low nor too high.

(a) Give a curved-arrow mechanism for the decarboxylation reaction shown in Fig.

(b) Explain why very low or very high $\mathrm{pH}$ values reduce the rate of this decarboxylation.

(c) The decarboxylation of acetoacetic acid is catalyzed by primary amines (amines of the form $\mathrm{R}-\mathrm{NH}_2$ ). Explain.

acetoacetic acid

Give a curved-arrow mechanism for each of the reactions given in Fig.

In the garden pea, several different genes affect pod characteristics. A gene affecting pod color (green is dominant to yellow) is approximately $7 \mathrm{mu}$ away from a gene affecting pod width (wide is dominant to narrow). Both genes are located on chromosome 5. A third gene, located on chromosome 4, affects pod length (long is dominant to short). A true-breeding wild-type plant (green, wide, long pods) was crossed to a plant with yellow, narrow, short pods. The $F_1$ offspring were then test-crossed to plants with yellow, narrow, short pods. If the testcross produced 800 offspring, what are the expected numbers of the eight possible phenotypic combinations?

Organolithium reagents such as methyllithium $\left(\mathrm{CH}_3 \mathrm{Li}\right)$ react with carboxylic acids to give ketones . Two equivalents of the lithium reagent are required, and the ketone does not react further. Suggest a mechanism for this reaction that accounts for these facts. Give the product of the reaction given in part (b) of Fig.

Complete each of the reactions given in Fig. by giving the principal organic product(s). Give the reasons for your answers.

$$\mathrm{Br}-\mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2-\mathrm{CO}_2 \mathrm{H} \underset{\text { acetone }}{\stackrel{\mathrm{K}_2 \mathrm{CO}_3}{\longrightarrow}}\left(\mathrm{C}_5 \mathrm{H}_8 \mathrm{O}_2\right)$$

Give the structure of the compound $\mathrm{C}_7 \mathrm{H}_5 \mathrm{O}_2 \mathrm{Cl}$ that has an IR absorption at $1685 \mathrm{~cm}^{-1}$ as well as a strong, broad $\mathrm{O}-\mathrm{H}$ absorption, and the following proton NMR spectrum: $\delta 7.56(2 H$, leaning d, $J=10 \mathrm{~Hz}) ; \delta 8.00(2 H$, leaning d, $J=10 \mathrm{~Hz}) ; \delta 8.27(1 H$, broad $\mathrm{s}$, exchanges with $\mathrm{D}_2 \mathrm{O}$ ).

Squaric acid (see following structure) has $\mathrm{p} K_{\mathrm{a}}$ values of about 1 and 3.5. Draw the reactions corresponding to the two successive ionizations of squaric acid and label each with the appropriate $\mathrm{p} K_{\mathrm{a}}$ value.

squaric acid Most enols have $\mathrm{p} K_{\mathrm{a}}$ values in the $10-12$ range. Using polar and resonance effects, explain why squaric acid is much more acidic. Given that squaric acid behaves like a dicarboxylic acid, draw structures for the products formed when it reacts with excess $\mathrm{SOCl}_2$; with ethanol solvent in the presence of an acid catalyst.

Electron Transfer to a Hill Reagent

Isolated spinach chloroplasts evolve $\mathrm{O}_2$ when illuminated in the presence of potassium ferricyanide (a Hill reagent), according to the equation

$$2 \mathrm{H}_2 \mathrm{O}+4 \mathrm{Fe}^{3+} \longrightarrow \mathrm{O}_2+4 \mathrm{H}^{+}+4 \mathrm{Fe}^{2+}$$

where $\mathrm{Fe}^{3+}$ represents ferricyanide and $\mathrm{Fe}^{2+}$, ferrocyanide. Is NADPH produced in this process? Explain.

The enzyme inorganic pyrophosphatase contributes to making many biosynthetic reactions that generate inorganic pyrophosphate essentially irreversible in cells. By keeping the concentration of PP$_i$ very low, the enzyme "pulls" these reactions in the direction of PP$_i$ formation. The synthesis of ADP-glucose in chloroplasts is one reaction that is pulled in the forward direction by this mechanism. However, the synthesis of UDP-glucose in the plant cytosol, which produces PP$_i$, is readily reversible in vivo. How do you reconcile these two facts?

Decarboxylation of compound A gives two separable products; draw their structures and explain.

How many products are formed when compound B is decarboxylated?

Propose a synthesis of each of the following compounds from the indicated starting material(s) and any other necessary reagents. (a) 2-pentanol from propanoic acid

(c) 2-methylheptane from pentanoic acid (d) m-nitrobenzoic acid from toluene (e) $\mathrm{PhCH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{Ph}$ from benzoic acid (h) 5-oxohexanoic acid from 5-bromo-2-pentanone

Incase, draw the structure of the cyclic anhydride that forms when the dicarboxylic acid is heated. meso- $\alpha, \beta$-dimethylsuccinic acid

The relatively stable carbocation crystal violet has a deep blue-violet color in aqueous solution. When NaOH is added to the solution, the blue color fades because the carbocation reacts with sodium hydroxide in about 1-2 min to give a colorless product. Show the reaction of crystal violet with NaOH and explain why the color changes.

crystal violet When the detergent sodium dodecyl sulfate (SDS) is present in solution above its critical micelle concentration, the bleaching of crystal violet with $\mathrm{NaOH}$ takes several days. Account for the effect of SDS on the rate of this bleaching reaction.

$$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{OSO}_3^{-} \mathrm{Na}^{+}$$

sodium dodecyl sulfate (SDS)