Primary by-products

The ultraviolet lamps used in the photochlorination process serve to dissociate the chlorine into free radicals and start the radical-chain reaction. Other radical sources, such as 2,2 -a2obisisobutyronitrile, have been used (63,64). Primary by-products of the photochlorination process include 1,1,2-trichloroethane (15—20%), tetrachloroethanes, and pentachloroethane. Selectivity to 1,1,1-trichloroethane is higher in vapor-phase chlorination. Various additives, most containing iodine or an aromatic ring in the molecule, have been used to increase the selectivity of the reaction to... 

Thus, in tetrahydrofuran solution, indole 1093 (R =(CH2)2NHAc) was converted to tetracyclic lactam 1094 (in 46% yield as a single diastereomer) in the presence of CpCo(C2H4)2 and acetylene gas (the experiment was performed on a submillimolar scale). The primary by-products of this reaction, isolated in 20-30% yield, are the cis- and trans- (3 1) cinnamic amides 1095. Presumably, these arise from the cyclization of the terminal acetylene moiety of indole 1093 with two acetylene molecules and subsequent equilibration. Attempts to scale-up the procedure to 0.5 mmol or more of indole 1093 led to a significant decrease in yield (17-24%) of tetracycle 1094. The main product of the reaction was amide 1095, isolated in 50-60% yield as a mixture of cis- and /ra j-isomers. Utilizing the reactivity of CpCo(C2H4)2 at low temperatures to minimize cyclobutadiene formation, reaction of unsubstituted enynoylindole 1093 (R = H) with bis(trimethylsilyl)acetylene (R = TMS), which is resistant to... 

Initial extraction of oil from oil fruit produces a cake of fruit skin, pulp, and kernel known as olive pomace or omjos. The value of this primary by-product of oil extraction depends on its oil and water contents, which are, in turn, determined by the method of oil extraction employed and the operating conditions. Pressure extraction yields a residue containing 4—5% oil, whereas classical presses leave 8-12% oil in the pomace (72). Pomace flours are used as animal feed due to their high content of protein, which is also of high quality. 

The catalyst for the oxygen-based process has a selectivity of ethylene to ethylene oxide which varies with different licensors between 70 and 80%. A selectivity of 75% is used in carrying out the following material balance calculation. The balance of the ethylene forms a small amount of byproducts, acetaldehyde and formaldehyde, but the primary by-product is carbon dioxide. For simplification it is assumed that the balance of the ethylene forms carbon dioxide. The following equations apply ... 

The secondary aim is to make use of residues as primary or secondary by-product. Primary by-products are residues that are also generated in a definite production process besides the target product and economically used without prior treatment, i.e. raw materials for other syntheses. Secondary by-products are the resulting residues from a process that are treated outside the considered unit in order to gain immediately usable value-added products. The outside treatment also mostly generates waste materials. Secondary by-products are matures. The main components are considered those mixture components that represent the usable portion of the material. 

The first reaction is the desired reaction the second reaction is that responsible for formation of the primary by-product. 

Cyclone firing It refers to slagging combustion of coarsely pulverized coal in a cylindrical (cyclone) burner. Some wet-bottom boilers are not cyclone-fired. The primary by-product is a glassy slag referred to as boiler slag. 

Epichlorohydrin (ECH) is an effective linking group between tertiary amines and acid salts and is used to produce sulfonated amphoterics known as sulfobetaines. Sodium sulfite is reacted with epichlorohydrin in water to produce a solution of l-chloro-2-hydroxypropane sulfonate, which is further reacted with a tertiary amine to yield a quaternary ammonium group linked to the hydroxy-propane sulfonate, with sodium chloride as the primary by-product. Reaction of ECH with partially neutralized phosphorous or phosphoric acid produces an intermediate, which when reacted with tertiary amines yields the respective phosphitobetaines or phosphatobetaines. 

Equilibrium constants for the reactions involving the conponents found in the laboratory studies on the benzene reaction are published [2]. The primary by-product at high tenperatures is diphenyl, formed by the following reaction. 

There are several explanations for the large concentration of monomers present under neutral and basic conditions. From Fig, 21 we see that the rate of hydrolysis of siloxane bonds increases by over three orders of magnitude between pH 4 and 7. Because hydrolysis occurs preferentially at less highly condensed Q sites [1], monomers are the primary by-product of siloxane bond hydrolysis. In a related study, Klemperer and Ramamurthi [93] have shown that siloxane bonds are broken by redistribution reactions under basic conditions (Eq. 42) that produce unhydrolyzed monomers as a by-product. In addition, from the pH-dependence of the hydrolysis reaction (Fig. 9), we see that the hydrolysis rate is minimized at neutral pH. Because the rate constant of the alcohol-producing condensation reaction is less than that of the water-producing reaction [63,95], unhydrolyzed or partially hydrolyzed monomers may persist in solution past the gel point. Presumably these combined factors contribute to the large concentrations of monomers observed under neutral and basic conditions. 

By the electrolysis of concentrated sodium chloride solution this process was initially used primarily for the production of sodium hydroxide but the demand for chlorine is now so great that the chlorine is a primary and not a by-product. 

P -f lOROH -f 5Br, — 2H3PO, -f lORBr -f 2H,0 The reaction is of general application with primary alcohols (n propyl to n hexadecyl) the yields are over 90 per cent, of the theoretical, but with secondary alcohols the yields are 50-80 per cent. in the latter case a small quantity of high boiling point by-product is also formed which can, however, be readily removed by fractional distillation. The reaction is conveniently carried out in a special all glass apparatus. 

The oxidative coupling of alkenes which have two substituents at the 2 posi-tion, such as isobutylene, styrene, 2-phenylpropene, 1,1-diphenylethylene, and methyl methacrylate, takes place to give the 1,1,4.4-tetrasubstituted butadienes 285 by the action of Pd(OAc)2 or PdCF in the presence of sodium acetate[255-257]. Oxidation of styrene with Pd(OAc)2 produces 1.4-diphenylbutadiene (285, R = H) as a main product and a- and /3-acetoxystyrenes as minor pro-ducts[258]. Prolonged oxidation of the primary coupling product 285 (R = Me) of 2-phenylpropene with an excess of Pd(OAc)2 leads slowly to p-... 

The primary dihydro product (3) can be obtained by reduction of the quinoid (4). Compound 3, in which Ri = CeH= -CH= and Rj CgH can also be obtained by direct condensation of benzylidene selenosemicar-bazone with 2.3-dibromo-l,4-diphenyl-l,4-butanedione (Scheme 49). 

The fermentative fixing of CO2 and water to acetic acid by a species of acetobacterium has been patented acetyl coen2yme A is the primary reduction product (62). Different species of clostridia have also been used. Pseudomonads (63) have been patented for the fermentation of certain compounds and their derivatives, eg, methyl formate. These methods have been reviewed (64). The manufacture of acetic acid from CO2 and its dewatering and refining to glacial acid has been discussed (65,66). 

In the United States, more than 16.3 x 10 kg of human-inedible raw materials are available each year, and the rendering industry is a valuable asset in diverting these into valuable ingredients for use primarily in animal foods (4). The three largest meat packers are responsible for nearly four-fifths of aU red meat production (5) and enormous amounts of rendered meat meal and animal fat. Three broiler producers account for about 40% of the total broiler production. American Proteins, Inc. (RosweU, Georgia), the world s largest processor of poultry by-products, produces more than 450,000 t of poultry meal, feather meal, and poultry fat each year. It also produces more than 100,000 t of fish meal, fish oil, and fish products each year. Pish meal production worldwide in 1986 was estimated at 6.23 x 10 t, which with the 125 x 10 t of meat and bone meal plus 6.67 x 10 t of feather meal and poultry by-product meal (6) is the primary source of animal proteins used by the pet food industry. 

Since the early 1980s olefin plants in the United States were designed to have substantial flexibiHty to consume a wide range of feedstocks. Most of the flexibiHty to use various feedstocks is found in plants with associated refineries, where integrated olefins plants can optimize feedstocks using either gas Hquids or heavier refinery streams. Companies whose primary business is the production of ethylene derivatives, such as thermoplastics, tend to use ethane and propane feedstocks which minimize by-product streams and maximize ethylene production for their derivative plants. 

The ores of most importance are fluorspar, CaF2 fluorapatite, Ca (P0 2Fj cryoHte [15096-52-3], Na AlF. Fluorspar is the primary commercial source of fluoiine. Twenty-six percent of the world s high quaHty deposits of fluorspar are ia North America. Most of that is ia Mexico. United States production ia 1987—1991 was 314,500 metric tons, most of which occurred ia the Illinois-Kentucky area. Imported fluorspar ia 1990—1991 represented about 82% of U.S. consumption 31% of U.S. fluorspar imports were from Mexico and 29% from China compared to 66% from Mexico ia the 1973—1978 period. The majority of the fluorine ia the earth s cmst is ia phosphate rock ia the form of fluorapatite which has an average fluorine concentration of 3.5%. Recovery of these fluorine values as by-product fluorosiHcic acid from phosphate production has grown steadily, partially because of environmental requirements (see Phosphoric acid and THE phosphates). 

Products do not contain 2,2,3-trimethylbutane or 2,2,3,3-tetramethylbutane, which would be expected as the primary alkylation products of direct alkylation of isobutane with propylene and isobutylene, respectively. In fact, the process iavolves alkylation of the alkenes by the carbocations produced from the isoalkanes via intermolecular hydride abstraction. 

Hafnium is obtained as a by-product of the production of hafnium-free nuclear-grade 2irconium (see Nuclear reactors Zirconiumand zirconium compounds). Hafnium s primary use is as a minor strengthening agent in high temperature nickel-base superakoys. Additionally, hafnium is used as a neutron-absorber material, primarily in the form of control rods in nuclear reactors. 

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