Formed in situ

It is however more complicated, esters of phosphorous acid being also formed (c/. p. 308). Iodides are usually prepared by a modification of this method, the ethanol being mixed with red phosphorus, and iodine added. The phosphorus iodide is thus formed in situ, and at once reacts with ethanol to give the corres ponding iodide. 

The phenylacetic acid derivative 469 is produced by the carbonylation of the aromatic aldehyde 468 having electron-donating groups[jl26]. The reaction proceeds at 110 C under 50-100 atm of CO with the catalytic system Pd-Ph3P-HCl. The reaction is explained by the successive dicarbonylation of the benzylic chlorides 470 and 471 formed in situ by the addition of HCl to aldehyde to form the malonate 472, followed by decarboxylation. As supporting evidence, mandelic acid is converted into phenylacetic acid under the same reaction conditions[327]. 

The Li compound 588 formed by the ort/io-lithiation of A. A -dimethylaniline reacts with vinyl bromide to give the styrene derivative 589(433]. The 2-phe-nylindole 591 is formed by the coupling of l-methyl-2-indolylmagnesium formed in situ from the indolyllithium 590 and MgBr2, with iodobenzene using dppb[434]. 2-Furyl- and 2-thienyllithium in the presence of MgBr2 react with alkenyl halides[435]. The arylallenes 592 and 1,2,4-alkatrienes are prepared by the coupling reaction of the allenyllithium with aryl or alkenyl halides[436]. 

Indol-3-ylcarbinols can also be reduced using Et3SiH-TFA. Aryl indolyl-3-ylcarbinols can be formed in situ from 2-alkylindoles and benzaldehydes. These reactions, when run in tandem, provide a versatile route to 3-benzylin-doles[l 1]. Indole itself undergoes reduction to indoline under these conditions. lndol-3-ylcarbinols can also be generated by organomelallic additions to 3-acylindoles[12]. 

Q or Br designates the corresponding a-chloro or a-brorao-aldehyde or ketone PjS5 designates thioanrides formed in situ from amides. 

The only method that yields the 2-unsubstituted thiazoie derivatives directly involves the condensation of a-haloketones with thioformamide. As in the case of previously reported a-haloaldehydes, yields are better when more reactive bromoketones are used instead of a-chloroketones. Cyclization can be achieved by adding ketones dissolved in dioxane in small quantities to the thioformamide formed in situ at below 40°C. The temperature is kept below 70°C during the addition, and then the... 

Sodium Chloroacetate Sodium chloroacetate [3926-62-3] mol wt 116.5, C2H2C102Na, is produced by reaction of chloroacetic acid with sodium hydroxide or sodium carbonate. In many appHcations chloroacetic acid or the sodium salt can be used interchangeably. As an industrial intermediate, sodium chloroacetate may be purchased or formed in situ from free acid. The sodium salt is quite stable in dry soHd form, but is hydrolyzed to glycoHc acid in aqueous solutions. The hydrolysis rate is a function of pH and temperature (29). 

Unusual reducing properties can be obtained with borohydride derivatives formed in situ. A variety of reductions have been reported, including hydrogenolysis of carbonyls and alkylation of amines with sodium borohydride in carboxyHc acids such as acetic and trifluoroacetic (38), in which the acyloxyborohydride is the reducing agent. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

In pigments, 2irconium sHicate serves as the host lattice for various chromophores, such as vanadium, praseodymium, iron, etc. Zirconium sHicate crystals are usuaHy formed in situ during pigment preparation by a high temperature reaction of Zr02 and Si02 ... 

Stability, and can provide both ohmic low resistance contacts and rectifying contacts. Typically, siUcide layers are formed in situ by sputteriag a thin platiaum layer onto the siUcon surface, followed by sintering. Infrared detection is another appHcation of platiaum siUcide technology. 

Nucleophilic Substitution Route. Commercial synthesis of poly(arylethersulfone)s is accompHshed almost exclusively via the nucleophilic substitution polycondensation route. This synthesis route, discovered at Union Carbide in the early 1960s (3,4), involves reaction of the bisphenol of choice with 4,4 -dichlorodiphenylsulfone in a dipolar aprotic solvent in the presence of an alkaUbase. Examples of dipolar aprotic solvents include A/-methyl-2-pyrrohdinone (NMP), dimethyl acetamide (DMAc), sulfolane, and dimethyl sulfoxide (DMSO). Examples of suitable bases are sodium hydroxide, potassium hydroxide, and potassium carbonate. In the case of polysulfone (PSE) synthesis, the reaction is a two-step process in which the dialkah metal salt of bisphenol A (1) is first formed in situ from bisphenol A [80-05-7] by reaction with the base (eg, two molar equivalents of NaOH),... 

Other Materials. Benzoguanamine and acetoguanamine may be used in place of melamine to achieve greater solubiHty in organic solvents and greater chemical resistance. Aniline and toluenesulfonamide react with formaldehyde to form thermoplastic resins. They are not used alone, but rather as plasticizers (qv) for other resins including melamine and urea—formaldehyde. The plasticizer may be made separately or formed in situ during preparation of the primary resin. 

Soil conditioners are materials that measurably improve the physical characteristics of the soil as a plant growth medium. Typical uses include erosion control, prevention of surface sealing, and improvement of water infiltration and drainage. Many natural materials such as peat and gypsum are used alone or in combination with synthetics for soil conditioning. This article is concerned with synthetic soil conditioners, many of which are introduced as polymeric systems similar to the gels and foams formed in situ by chemical grouts. 

Dynamic membranes are concentration—polarization layers formed in situ from the ultrafiltration of coUoidal material analogous to a precoat in conventional filter operations. Hydrous zirconia has been thoroughly investigated other materials include bentonite, poly(acryhc acid), and films deposited from the materials to be separated (18). 

Chromium carbide is important in powder preparations designed for thermal spray apphcations of corrosion and wear-resistant coatings on tool and machine parts. Lower carbon carbides of chromium are important in hardfacing tods and electrodes for weld-apphed ovedays on machine wear surfaces. However, these carbides are usually formed in situ from Cr and C in the rod and not added as preformed carbides. The properties of Ci2C2 are hsted in Table 2. 

The hydrocarbon is carried in a stream of H2 or Ar, and P-SiC is formed or P-SiC is formed by reaction in the gas phase, under static conditions, of compounds such as SiO or CO formed in situ during the process. In this latter case the important reaction appears to be SiO + 3CO — SiC + 2CO2. This... 

Self-baked carbon electrodes are those whose shapes are formed in situ (33). The carbonaceous mixture is placed into a hoUow tube-shaped metal casing. The upper end receives the unbaked mixture as a soHd block, small particles, or warm plastic paste. The casing contains inwardly-projecting longitudinal perforated fins that become surrounded by baked carbon as the casing is incrementally moved downward and through the contact plates. Casing and carbon are consumed in this furnace. 

Emission Control Catalysts. An appHcation of growing importance for cerium is as one of the catalyticaHy active components used to remove pollutants from vehicle (autoexhaust) emissions (36). The active form of cerium is the oxide that can be formed in situ by calciaation of a soluble salt such as nitrate or by deposition of slurried oxide (see Exhaust control, automotive). 

Stable A/-chloro compounds are formed by reaction of hypochlorous acid and appropriate N—H compounds. For example, HOCl, formed in situ via chlorine hydrolysis, converts di- or trisodium cyanurates to dichloro- and trichloroiso-cyanuric acids, respectively (114). Chloroisocyanurates can also be prepared from isocyanuric acid or monosodium cyanurate and preformed HOCl (115—117). Hydrolysis of chloroisocyanurates provide HOCl for use in swimming pool disinfection and in bleaching appHcations. 

Uses. Chloric acid is formed in situ by reaction of sodium chlorate and a strong acid during chlorine dioxide production. Stoichiometric amounts... 

Reactions of 6-aminouracils with various 2-substituted cyclohexanones such as the aldehyde (264) give reduced pyrimido[4,5-f ]quinolines (265) (57BRP774095, 58JA3449), and other cyclohexanone derivatives used include the 2-dimethylaminomethyl (Mannich) bases (78AP542) and the 5-benzylidenedimedones (266) formed in situ from dimedone and aldehydes (67KGS395, cf. 67KGS406). 

Aldehydes and ketones react with azolinones. The reaction between aldehydes and 2-phenyl-5-oxazolinone (131 Y = H), formed in situ from PhC0NHCH2C02H and AC2O, gives azlactones (131 Y = RCH). Similar reactions are given by 4-thiazolidinones, e.g. (132) gives (133) (79AHC(25)83), and 4-imidazolinones. In pyrazolin-5-ones the 4-position is sufficiently activated for condensation to occur with ketones in acidic media (Scheme 8) (66AH06)347). 

First order decomposition was established for dimethyldiazirine (215) and ethylmethyl-diazirine (216). The activation energy is 139 kJ moF for (215) the half life at 100 °C is 97 h. On decomposition of (216) the products formed and their respective yields are as indicated. The products correspond qualitatively and quantitatively with the results of thermal decomposition of 2-diazobutane formed in situ in aprotic solvents. Analogous comparisons of decomposition products of diethyldiazirine, isopropylmethyldiazirine, n-butyl- and t-butyl-diazirine agree equally well 66TL1733). 

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