3-Chloro-1,2-propanediol → 1,2-Bis(2,3-dihydroxypropyloxy)-4,5-dinitrobenzene

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Reaction Steps

8C, FIG. 8. 1,2-Dihydroxy-4,5-dinitrobenzene 8B (5.0 g, 22 mmol) and 1-chloro-2,3-dihydroxypropane (12.1 g, 110 mmol) were refluxed for 48 hours in a solution of potassium hydroxide (4.4 g) in 1-butanol (100 mL) under a nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure, and the dark residue was partitioned between 100 mL of THF and 100 mL of brine/50 mL water solution in a 500 mL separatory funnel. The mixture was allowed to separate and the aqueous phase was extracted with THF (2×100 mL). The combined THF extracts were washed with brine (2×50 mL), dried over MgSO4 and concentrated to an oily residue. Here, CH2Cl2 was added very carefully to insure precipitation of the crude product. After stirring for 15 minutes, the suspension was filtered with a medium glass fritted funnel and air dried for several minutes. The orange solid was taken up in 120 mL of CHCl3 and 80 mL of diethyl ether at reflux and hot filtered to remove some impurities. The crude product was dissolved in a mixture of acetone and methanol (sonication may be required), then 6 grams of deactivated silica gel was added to the orange solution. The slurry was concentrated to dryness and the orange solid was dried in vacuo for one hour. The orange solid was loaded on a packed deactivated silica gel column. The column was eluted starting with neat CHCl3 followed by CHCl3 with increasing concentration of methanol (0-10%). After a bright yellow impurity (monoalkylated product) was removed a colorless product began to elute (using 8-10% methanol in CHCl3 eluents). Conversely, on TLC the product will elute faster than the bright yellow monoalkylated product. The purified dialkylated tetrahydroxy product can be recrystallized from acetone/diethyl ether to yield 2.60 grams (30%) of a light yellow fluffy solid. 1H NMR (d6 -acetone): δ2.95 (bs, 4H, OH), 3.69 (d, 4H, OCH2CH(OH)CH2OH), 4.06 (p, 2H, OCH2CH(OH)CH2OH), 4.24-4.35 (m, 4H, OCH2CH(OH)CH2OH), 7.72 (s, 2H, Ar--H); 13C NMR (d6 -acetone): δ63.55, 70.89, 72.53, 109.99, 137.22, 152.77. CI MS 349.

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