Quench Reaction with Water

The chemistry of the naphthalene radical anion in quench reactions with water, carbon dioxide, or alky iodides involves several steps 165 167> (Eqs. 14-16) ... 

The in situ generation of the carbon dioxide adduct of an indole provides sufficient protection and activation of an indole for metalation at C-2 with r-butyl-lithium. The lithium reagent can be quenched with an electrophile, and quenching of the reaction with water releases the carbon dioxide. ... 

Fluorination of bicyclic derivatives, which has been used in prostaglandin synthesis from nor-bornadicne, gives a 1 1 mixture of two isomeric ot-fluoro esters, e.g. 3.18 The reaction is performed in tetrahydrofuran at — 78 °C, while a violent explosion occurs if the reaction is performed at — 40 C (upon quenching the reaction with water). 

Tetrahydrofuran (350 cm3), sodium borohydride (14.1 g) and (la,5a,6a)-3-N-benzyl-6-nitro-2,4-dioxo-3-azabicyclo[3.1.0]hexane (35.0 g, mmol) obtained above were stirred under nitrogen for 0.25 h and then treated dropwise with boron trifluoride-THF complex containing 21.5% BF3 (44.9 cm3) so that the exotherm was controlled to <40°C. After addition was completed, the reaction mixture was stirred for 3 h at 40°C, quenched slowly with water/THF 1 1 (70 cm3) to avoid excessive foaming, and stirred for 0.5 h at 50°C to ensure that the quench of unreacted diborane generated in situ was completed. The quench formed a salt slurry which was filtered and washed with THF (140 cm3) the combined filtrate was partially concentrated, diluted with water (350 cm3) and further concentrated to remove most of the THF, and extracted with ethyl acetate (140 cm3). The resulting ethyl acetate solution was concentrated to afford the (la,5a,6a)-3-N-benzyl-6-nitro-3-azabicyclo[3.1.0]hexane as a clear oil (30.6 g, 97%). 

The resulting tertiary cation is not isolated but quenched in the reaction mixture with water. One new stereogenic centre is set up in the cyclization and another in the reaction with water. In the cyclization the molecule prefers to fold in such a way that the new ring junction is cis. 

Treatment of isochroman-l-one derivatives 145 with lithio methoxyallene followed by quenching the reaction with water furnishes 3-benzoxocin-6-one derivatives 146 in good yields (Scheme 37) <2004SL481>. 

To concentrated sulfuric acid (70 ml) and water (55 ml) at 90°C is added benzimidazole (5 g), followed by powdered potassium dichromate (37 g). After 10-15 min the reaction is quenched carefully with water. The product is filtered, and washed with water in about 70% yield, m.p. 290°C (dec.). Similar oxidation of 2-methylbenzimidazole gives 2-methylimidazole-4,5-dicarboxylic acid (52%). 

An alternative workup, suitable for higher boiling products, involves quenching the reaction with water, drying, removal of the solvent and distillation. ... 

Benzyl alkoxide, generated from benzyl alcohol and potassium hydride, reacted with 1,1-bis-(benzenesulfonyl)cyclopropane (5a) to give 3-benzyloxy-l,l-bis(benzenesulfonyl)propane (6a) after quenching the reaction with water. The reactivity of benzenesulfonyl-substituted cyclopropanes towards nucleophiles was demonstrated by the reaction of methyl 2,2-dimethyl-l-benzenesulfonylcyclopropanecarboxylate (6b) with methanol which added across the most substituted cyclopropyl bond. ... 

In an alternative procedure to autoxidation, mesitylene iodosoacetate has been used for the oxidation of 2-dimethylaminoethyl 2,5-dimethylphenyl ether to 2-dimethylaminoethyl 4-hydroxy-2,5-dimethylphenyl ether (ref48). The starting phenol in acetic anhydride containing mesitylene iodosoacetate was treated slowly below 10°C with sulphuric add and after a reaction time of approximately 18 hours the mixture was quenched at with water and, following a work-up involving addition of ether and cuprous chloride, the product was isolated in 61 % yield. 

This endothermic plasma-chemical process was considered in Section 5.11.1. The process requires super-ideal quenching and separation of the products by fast plasma rotation similar to the case of plasma-chemical H2S dissociation (see Sections 10.7.5 and 10.7.6, and Fig. 5-76). The plasma-chemical stage (10-94), using off-peak electricity, can be a key step in the following HBr cycles of hydrogen production from water. The first cycle, proposed by Parker and Clapper (2001), applies the bromine produced in plasma (10-94) for reaction with water ... 

A first patent for the technical implementation of ozonolysis of OA was claimed by Rieche [21]. According to a BASF patent filed in 1941, AA (97%) and PA (95%) are accessible by treatment of the ozonide with alkaline lye and Ag20 [22]. However, the technical manufacturing of AA succeeded first by Emery Industries in the year 1953 [23]. Their successor Emery Oleochemicals is still the worlds largest producer of AA by ozonolysis of OA with a production volume of about lOOOOt/year [9, 24]. The achievable yield of AA is 70-80% [24], based on the amount of applied OA. AA yields of more than 90% were obtained in a pilot plant [25]. The reaction is carried out in PA/water (70/30v/v) as solvent. The admixture of water reduces the formation of side products by removal of the heat of reaction via evaporative heat loss, and in addition, undesired reactive radicals are quenched by reaction with water [25, 26]. 

Dinitrogen pentoxide (generated by mixing streams of dinitrogen tetroxide and ozonized oxygen) allowed to react countercurrently with 1-octanol, which is added dropwise at the top of a glass-spiraled reaction column, then quenched immediately with water -> octyl nitrate (Conversion 93%) added to hexamethyl-phosphoramide followed by Na-nitrite and ethyl malonate as nitrous acid scavenger, then stirred 1 hr. at 45° 1-nitrooctane (Y 95% conversion 41%). F. e. s. G. B. Bachman and N. W. Connon, J. Org. Chem. 34, 4121 (1969). 

Hasegawa and Curran have shown that water serves not only as a proton source, but can also accelerate certain reductions [89]. An example is reported in Table 6.11. The presence of water is essential for the rapid conversion of A to B, and quenching dry reactions with water only serves to promote this conversion. 

Arylation accompanies nickel-catalyzed ring-opening deallylation of cyclic allylmalonate derivatives in the presence of arylzinc reagents (Scheme 5.51) [37]. The presence of magnesium bromide in the reaction mixture is important to increase the leaving group ability of the malonate moieties by chelation (Scheme 5.52). Addition of electrophiles, such as allyl bromide, instead of quenching the reaction with water results in further carbon-carbon bond formation. 

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