Salt, stages

When instead of the adds, alkyl halides or methyl p-toluenesulfonate were used as the initiator, the dimerization reaction stopped at the N-alkyl piperazinium salt stage (38). Hem also, dimer formation is favored in acetone while solvents of high polarity and solvating power tend to favor polymer formation. 

Ring expansion of dichlorocarbene cycloadducts may be followed by further carbene cycloaddition to give 70 and 71 (R2N = morphcjJino) (Scheme 36). In the case of the pyrrolidine enamine, the reaction stops at the eniminium salt stage (69) to give structures such as 72 and 73 on hydrolysis59,60. 

In a few cases the isolation of the free acid or lactone was carried out directly without the intermediate salt stage Fischer and Herborn isolated L-rhamnonic lactone by concentration of the aqueous solution after the bromide ions had been removed with lead carbonate, followed... 

The oxidation of L-rhamnose was carried out by Will and Peters and by Rayman. These workers isolated the lactone directly from the bromide-free solution without the intermediate salt stage. The product crystallized readily. This is one of the few instances where such a procedure can be carried out. As the calcium and barium salts were... 

If we view the Wittig reaction from an alkyl halide starting material (alkyl halide phosphonium salt phosphorus ylid alkene), the halogen-bearing carbon of an alkyl halide must contain at least one hydrogen as in 59 (for deprotonation at the phosphonium salt stage). 

Secondary and tertiary alkyl halides give olefins on occasions,223 and / -un-saturated alkyl halides give products of allylic rearrangement.224 -Dibromo-alkanes give bisphosphonium salts in satisfactory to high yield.225 Unlike di-bromomethane, tribromomethane reacts with triphenylphosphine only to the monoquaternary salt stage, the reaction being radical jin nature.226... 

Lead(IV) oxide can be prepared by the action of an alkaline chlorate(I) solution on a solution of a lead(II) salt. The reaction can be considered in two stages ... 

Toluene-p-sulphonamide can be similarly converted into the dimethyl-amide, but the methylation now occurs in two definite stages. First the sulphonamide dissolves in the sodium hydroxide to form the mono-sodium salt (see p. 252), which then reacts with the dimethyl sulphate to give the mono-... 

The product of this reaction as its sodium salt is called a Meisenheimer complex after the Ger man chemist Jacob Meisenheimer who reported on their formation and reactions in 1902 A Meisenheimer complex corresponds to the product of the nucleophilic addition stage in the addition-elimination mechanism for nucleophilic aromatic substitution... 

In the Strecker synthesis an aldehyde is converted to an a ammo acid with one more carbon atom by a two stage procedure m which an a ammo nitrile is an mterme diate The a ammo nitrile is formed by reaction of the aldehyde with ammonia or an ammonium salt and a source of cyanide ion Hydrolysis of the nitrile group to a car boxylic acid function completes the synthesis... 

After cleavage the reaction mass is a mixture of phenol, acetone, and a variety of other products such as cumylphenols, acetophenone, dimethyl-phenylcarbinol, a-methylstyrene, and hydroxyacetone. It may be neutralised with a sodium phenoxide solution (20) or other suitable base or ion-exchange resins. Process water may be added to facilitate removal of any inorganic salts. The product may then go through a separation and a wash stage, or go direcdy to a distillation tower. 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

Oxidation Step. A review of mechanistic studies of partial oxidation of propylene has appeared (58). The oxidation process flow sheet (Fig. 2) shows equipment and typical operating conditions. The reactors are of the fixed-bed shell-and-tube type (about 3—5 mlong and 2.5 cm in diameter) with a molten salt coolant on the shell side. The tubes are packed with catalyst, a small amount of inert material at the top serving as a preheater section for the feed gases. Vaporized propylene is mixed with steam and ak and fed to the first-stage reactor. The feed composition is typically 5—7% propylene, 10—30%... 

The preheated gases react exothermically over the first-stage catalyst with the peak temperature ia the range of 330—430°C, depending on conditions and catalyst selectivity. The conversion of propylene to waste gas (carbon dioxide and carbon monoxide) is more exothermic than its conversion to acroleia. At the end of the catalyst bed the temperature of the mixture drops toward that of the molten salt coolant. 

The catholyte from diaphragm cells typically analyzes as 9—12% NaOH and 14—16% NaCl. This ceUHquor is concentrated to 50% NaOH in a series of steps primarily involving three or four evaporators. Membrane cells, on the other hand, produce 30—35% NaOH which is evaporated in a single stage to produce 50% NaOH. Seventy percent caustic containing very Httie salt is made directiy in mercury cell production by reaction of the sodium amalgam from the electrolytic cells with water in denuders. 

The precipitated cellulose acetate is filtered from the dilute (25—36%) acetic acid. The acetic acid and salts remaining from the sulfuric acid neutrali2ation are removed by washing. The wet polymer is typically dried to a moisture content of 1—5%. The dilute acetic acid obtained from the washing and precipitation steps caimot be used in other stages of the process. Its efficient recovery and recycle are an economic necessity. 

Ornamentals are treated with GA for a variety of purposes including more profuse flowering, increasing flower number, and in some circumstances flower size. It is a common practice in the southeastern United States to gib camelHas prior to flowering, ie, a small amount of the potassium salt of GA at 100 ppm is dropped into the floral bud at a very early stage of development to produce large showy flowers. 

Hot Corrosion. Hot corrosion is an accelerated form of oxidation that arises from the presence not only of an oxidizing gas, but also of a molten salt on the component surface. The molten salt interacts with the protective oxide so as to render the oxide nonprotective. Most commonly, hot corrosion is associated with the condensation of a thin molten film of sodium sulfate [7757-82-6], Na2S04, on superaHoys commonly used in components for gas turbines, particularly first-stage turbine blades and vanes. Other examples of hot corrosion have been identified in energy conversion systems, particularly coal gasifiers and direct coal combustors. In these cases the salt originates from alkali impurities in the coal which condense on the internal... 

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