Arnold reagents

BF3 Et20 reacts with fluorinated amines to form salts which are analogous to Vils-meier reagents, Arnold reagents, or phosgene-immonium salts (Eq. 77) [131]. These salts can be used to acylate electron-rich aromatic compounds, introducing a fluorinated carbonyl group (Eq. 78). 

Dimethylamino)-4 -(diethylaniiiio)-diphenylmethane (Arnold s reagent) + 1,3-Dinitrobenzene... 

Feringa, B. L. Naasz, R. Imbos, R. Arnold, L. A. Copper-catalyzed Enantioselective Conjugate Addition Reactions of Organozinc Reagents. In Modem Organocopper Chemistry Krause, N. Ed. Wiley-VCH GmbH Weinheim, 2002 Chapter 7, pp 224—258. 

Arnold, S.M., Hickey. W.J.. and Harris. R.F. Degradation of atrazine by Fenton s reagent condition optimization and product quantification. Environ. Sci. Technol, 29(8) 2083-2089,1995. 

Table 6.8 shows that the fastest depletion of atrazine occurs under Fenton s reagent. Arnold et al. (1995) demonstrated that OH may react with Ch at low pH to produce HOC1 and Cl2, causing underestimation of Cl concentrations, but the results suggest that Cl- scavenging by OH was minimal. Dechlorination and dealkylation occur simultaneously, and the batch treatment showed that dechlorination occurred more readily with alkylated s-triazines. Chlorinated products accounted for a large part of s-triazines present upon completion of Fenton s reagent. 

Degradation pathway for atrazine treated with Fenton s reagent. (From Arnold, S.M. et al., Environ. Sci. Technol., 29, 2083, 1995. With permission.)... 

Arnold and co-workers also reported the deprotonation of alkoxy imi-dazolium iodides with -butyl lithium to yield lithium alkoxide carbenes (Scheme 3).14 Single crystals of one of the complexes were grown from a diethyl ether solution, and revealed a dimer of LiL with lithium iodide incorporated to form a tetramer of lithium cations (7). The lithium-NHC bond distance of 2.131(6) A is similar to that of the lithium amide carbene 4. Also as in 4 there is distortion of the lithium-NCN bond which has an angle of 152.3°. The C2 carbon resonates at 200 ppm in the 13C NMR spectrum which is a relatively high-frequency, possibly as a result of the incorporated lithium iodide. The lithium salts were able to act as ligand transfer reagents and react with copper (II) chloride or triflate to afford mono- or bis-substituted copper(II) alkoxy carbene complexes. 

The Vilsmeier (or Vilsmeier-Haack or Vilsmeier-Haack-Arnold) reaction is primarily a mild method for formylating a wide variety of substrates.1 It has limited application to higher acylation and involves the reaction of a Vilsmeier reagent derived from a tertiary amide and an acid chloride (or occasionally a bromide). The most commonly employed amide is jV,N-dimethylformamide (DMF) and the acid chloride is generally phos-phoryl chloride, though phosgene and thionyl chloride are also employed. 

The reagent has found some use for the oxidation of aromatic hydrocarbons and phenols to para quinones. Arnold and Lawson " heated a mixture of 10 g. of naphthalene, 25 ml. of 30% hydrogen peroxide, and 50 ml. of acetic acid just above 80° for 45 min., distilled off about half of the solvent, added water to precipitate the product, and by crystallization isolated satisfactory 1,4-naphthoquinone in 20% yield. Durene (5 g.) was heated with HjOa-AcOH for 15 hrs. on the steam bath and duroquinone (2.1 g.) was separated by steam distillation. Crude 2-methyl-1,4-naphthoquinone and 2,3-dimethyl-l, 4-naphlhoquinone were obtained in yields of 30 and 78%. Unchanged hydrocarbon wax present at the end of each oxidation. 

The determination of nitrophenyl phosphate using alkaline phosphatase (Arnold, 1985) has been used as a model system for analytically important substrates. The enzyme is entrapped in the reagent layer of the optical sensor depicted in Fig. 7. The nitrophenyl phosphate substrate permeates from the sample into the layer and is there converted to the strongly yellow nitrophenol. The change in light absorption is proportional to the substrate concentration. 

Arnold et al. (1987) described an optoelectronic ethanol sensor based on fluorimetric detection of NADH formed in the reaction catalyzed by ADH. The enzyme was fixed to the inner surface of a membrane permeable to volatile substances, which separated the sample from the internal sensor solution. This solution contained NADH and semicarbazide, so that no reagent had to be added to the sample. The arrangement was named an internal optical enzyme sensor . 

Allylic esters having at least one aryl group and one H-atom attached to the a-carbon atom undergo intramolecular rearrangement, in the presence of strong basic reagents, to give a-allylic subst. acids.—E / -Methylallyl diphenylacetate boiled 22 hrs. in toluene with pulverized NaH—>- 2,2-diphenyl-4-methylpenten-4-oic acid. Y 76%. (F. e. s. R. T. Arnold andS. Searles, Jr., Am. Soc. 71,1150 (1949).)... 

Streicher, R. P., J. E. Arnold, M. K. Ernst, and C. V. Cooper. 1996. Development of a novel derivatization reagent for the sampling and analysis of total isocyanate group in air and comparison of its performance with that of several established reagents. Am. Ind. Hyg. Assoc. J. 57(10) 905-13. 

Arnold and Choudhury reported results derived from a lab scale extraction of soybean and cottonseed flakes in a tubular percolation extractor at 135-140T with pure, high purity and commercial hexane, and reagent grade benzene. They claimed that pure hexane extracted soybean slower than high purity and commercial hexane. During the first 60 minutes of extraction, benzene extracted more oil than the hexanes. However, at the end of 80 minutes, benzene extracted only slightly more than pure hexane but definitely less than the commercial hexanes. Similar results were obtained for the four solvents when cottonseed flakes were extracted. 

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