1.3- Dibromo-4,6-dinitrobenzene, reaction with

The parent system 4 has also been prepared employing a double reductive ring closure of a dinitrodiphenylbenzene derivative (Scheme 25). The required starting material, 195, was prepared using a palladium-catalyzed coupling of 1,4-dibromo-2,S-dinitrobenzene with pbenylboronic acid and after reaction with tri-ethylphosphite in hot tert-butylbenzene, 4 could be isolated in a moderate yield (92JHC1237). 

When l,2-dibromo-3,5-dinitrobenzene is treated with excess NaOH at 50 °C, only one of the bromine atoms is replaced. Draw an equation for this reaction, showing the product you expect. Give a mechanism to account for the formation of your proposed product. 

Prepared by the reaction of 3,5-dibromo-4-hydroxy-benzaldehyde oxime with 1-chloro-2,4-dinitrobenzene (BP 1 096 037), bromofenoxim is a postemergence selective herbicide with strong contact activity. It is used for the control of annual broad-leaved weeds in winter- and spring-sown cereals at a rate of 1-2.5 kg active ingredient/ha. To enhance the effect against grassy weeds, it is also available in combination with terbutylazine in active substance ratios of 3 1 and 1.65 1. 

The propeller polymer R)-54 is synthesized by the polymerization of (/ )-32 with l,2-dibromo-4,5-dinitrobenzene, 57, in the presence of Pd(PPh3)4/CuI catalysts. This reaction proceeds at room temperature in a triethylamine-THF solution (Scheme 21). GPC analysis of (iR)-54 shows = 18,000 and M = 12,000 (PDI = 1.5). The two bromine atoms in 57 are highly activated by the two para nitro groups, so the polymerization can take place under very mild conditions. (R)-54 is soluble in chloroform, methylene chloride, and THF. Its specific optical rotation is... 

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