Commercially prepared

These limitations have recently been eliminated using solid-state sources of femtosecond pulses. Most of the femtosecond dye laser teclmology that was in wide use in the late 1980s [11] has been rendered obsolete by tliree teclmical developments the self-mode-locked Ti-sapphire oscillator [23, 24, 25, 26 and 27], the chirped-pulse, solid-state amplifier (CPA) [28, 29, 30 and 31], and the non-collinearly pumped optical parametric amplifier (OPA) [32, 33 and 34]- Moreover, although a number of investigators still construct home-built systems with narrowly chosen capabilities, it is now possible to obtain versatile, nearly state-of-the-art apparatus of the type described below Ifom commercial sources. Just as home-built NMR spectrometers capable of multidimensional or solid-state spectroscopies were still being home built in the late 1970s and now are almost exclusively based on commercially prepared apparatus, it is reasonable to expect that ultrafast spectroscopy in the next decade will be conducted almost exclusively with apparatus ifom conmiercial sources based around entirely solid-state systems. 

The most connnon commercially prepared amplifier systems are pumped by frequency-doubled Nd-YAG or Nd-YLF lasers at a 1-5 kHz repetition rate a continuously pumped amplifier that operates typically in the 250 kHz regime has been described and implemented connnercially [40]. The average power of all of the connnonly used types of Ti-sapphire amplifier systems approaches 1 W, so the energy per pulse required for an experiment effectively detennines the repetition rate. 

Although benzenesulphonyl chloride has for simplicity been used in the above discussion, tolucne-/>- sulphonyl chloride, CHaCeH SO Cl, is more frequently used in the laboratory, owing to its much lower cost, the latter being due in turn to the fact that toluene-p-sulphonyl chloride is a by-product in the commercial preparation of saccharin. Toluene-p sulphonyl chloride is a crystalline substance, of m.p. 68° the finely powdered chloride will, however, usually react readily with amines in the Schotten-Baumann reaction it does not react so readily with alcohols, but the reaction may be promoted considerably by first dissolving the chloride in some inert water-soluble solvent such as acetone. 

Formaldehyde is a gas, b.p. — 21°, and cannot obviously be stored as such moreover, it polymerises readily in the liquid and the gaseous state. The commercial preparation, formalin, is an aqueous solution containing 35-40 per cent, of formaldehyde and some methyl alcohol. The preparation of a solution of formaldehyde may be demonstrated by the following experiment. 

Commercial preparations of acetyl chloride are best freed from volatile phos. phorus compounds and dissolved hydrogen chloride by redistillation from 5-10 per cent, of the volume of pure dimethylaniline. 

The details of the commercial preparation of acetal homo- and copolymers are discussed later. One aspect of the polymerisation so pervades the chemistry of the resulting polymers that familiarity with it is a prerequisite for understanding the chemistry of the polymers, the often subde differences between homo- and copolymers, and the difficulties which had to be overcome to make the polymers commercially useful. The ionic polymerisations of formaldehyde and trioxane are equiUbrium reactions. Unless suitable measures are taken, polymer will begin to revert to monomeric formaldehyde at processing temperatures by depolymerisation (called unsipping) which begins at chain ends. 

The vast majority of all commercially prepared acryUc polymers are copolymers of an acryUc ester monomer with one or more different monomers. Copolymerization gready increases the range of available polymer properties and has led to the development of many different resins suitable for a broad variety of appHcations. Several review articles are available (84,85). 

Only a few of the wide variety of synthetic procedures which yield aldehydes as products are used for large-scale commercial preparation. A more complete discussion of syntheses can be found ia the Hterature (10,11). 

The acceptabihty of food is deterrnined by its flavor, and a large variety of industrial flavorings are used for the commercial preparation of foods. Most of the daily food intake, even in industrialized countries, contains flavor naturally or flavor formed during cooking and preparation for human consumption. Only a minor part of the daily food intake is covered by foods containing added flavorings. 

Compounded Flavors. Liquid or dry blends of natural or synthetic flavor compounds are called compounded flavors. Most commercial preparations are available as water- and oil-soluble Hquids, spray-dried and plated powders, emulsions, and carbohydrate-, protein-, and fat-based pastes. Compounded flavors are used throughout the food industry in confections, baked goods, snack foods, carbonated beverages, and processed foods (53). 

Petfluotoalkanesulfonic acids also show high acidity. The parent trifluoromethanesulfonic acid (triflic acid), CF SO H, is commercially prepared by electrochemical fluorination of methanesulfonic acid (214). It has an value of —14.1 (215,216). The higher homologues show slightly decreasing acidities. 

Manufacture. Commercial preparation of neopentyl glycol can be via an alkah-cataly2ed condensation of isobutyraldehyde with 2 moles of formaldehyde (crossed Canni22aro reaction) (2,8). Yields are - 70%. 

A substantial fraction of commercially prepared methacrylic polymers are copolymers. Monomeric acryUc or methacrylic esters are often copolymerized with one another and possibly several other monomers. Copolymerization greatiy increases the range of available polymer properties. The aH-acryhc polymers tend to be soft and tacky the aH-methacryhc polymers tend to be hard and brittie. By judicious adjustment of the amount of each type of monomer, polymers can be prepared at essentially any desired hardness or flexibiUty. Small amounts of specially functionalized monomers are often copolymerized with methacrylic monomers to modify or improve the properties of the polymer directiy or by providing sites for further reactions. Table 9 lists some of the more common functional monomers used for the preparation of methacrylic copolymers. 

The principal iadustrial production route used to prepare fatty amines is the hydrogenation of nitriles, a route which has been used since the 1940s. Commercial preparation of fatty amines from fatty alcohols is a fairly new process, created around 1970, which utilizes petrochemical technology, Ziegler or Oxo processes, and feedstock. 

When the salt is heated to temperatures from 200 to 230°C, exothermic decomposition occurs (4,21). The reaction is rapid, but it can be controlled, and it is the basis for the commercial preparation of nitrous oxide [10024-97-2]. 

Because the regions of the alimentary tract vary widely ia pH and chemical composition, many different commercial formulations of barium sulfate are available. The final preparations of varyiag viscosity, density, and formulation stabiUty levels are controlled by the different size, shape, uniformity and concentration of barium sulfate particles and the presence of additives. The most important additives are suspending and dispersiag agents used to maintain the suspension stabiUty. Commercial preparations of barium sulfate iaclude bulk and unit-dose powders and suspensions and principal manufacturers are E-Z-EM (Westbury, New York), Lafayette-Pharmacol, Inc. (Lafayette, Indiana), and Picker International, Inc. (Cleveland, Ohio). 

Cationic Starches. The two general categories of commercial cationic starches are tertiary and quaternary aminoalkyl ethers. Tertiary aminoalkyl ethers are prepared by treating an alkaline starch dispersion with a tertiary amine containing a P-halogenated alkyl, 3-chloto-2-hydtoxyptopyl radical, or a 2,3-epoxypropyl group. Under these reaction conditions, starch ethers are formed that contain tertiary amine free bases. Treatment with acid easily produces the cationic form. Amines used in this reaction include 2-dimethylaminoethyl chloride, 2-diethylaminoethyl chloride, and A/-(2,3-epoxypropyl) diethylamine. Commercial preparation of low DS derivatives employ reaction times of 6—12 h at 40—45°C for complete reaction. The final product is filtered, washed, and dried. 

Efforts toward producing synthetic steroids, particularly cortisol, expanded during World War II to enable researchers to explore the possibiUty of medicinal appHcations of corticosteroids. In 1948, the discovery that cortisone dramatically alleviates the symptoms of arthritis led to intensive research on the antiinflammatory properties of corticosteroids. The development of partial and total syntheses for the commercial preparation of cortisone, alternative methods for producing cortisone, and the search for more potent antiinflammatory analogues gready stimulated both academic and industrial steroid research. 

Anionic polymerization, if carried out properly, can be truly a living polymerization (160). Addition of a second monomer to polystyryl anion results in the formation of a block polymer with no detectable free PS. This technique is of considerable importance in the commercial preparation of styrene—butadiene block copolymers, which are used either alone or blended with PS as thermoplastics. 

Sulfamic acid [5329-14-6] (amidosulfuric acid), HSO2NH2, molecular weight 97.09, is a monobasic, inorganic, dry acid and the monoamide of sulfuric acid. Sulfamic acid is produced and sold in the form of water-soluble crystals. This acid was known and prepared in laboratories for nearly a hundred years before it became a commercially available product. The first preparation of this acid occurred around 1836 (1). Later work resulted in identification and preparation of sulfamic acid in its pure form (2). In 1936, a practical process which became the basis for commercial preparation was developed (3,4). This process, involving the reaction of urea with sulfur trioxide and sulfuric acid, continues to be the main method for production of sulfamic acid. 

Processes that are essentially modifications of laboratory methods and that allow operation on a larger scale are used for commercial preparation of vinyhdene chloride polymers. The intended use dictates the polymer characteristics and, to some extent, the method of manufacture. Emulsion polymerization and suspension polymerization are the preferred industrial processes. Either process is carried out in a closed, stirred reactor, which should be glass-lined and jacketed for heating and cooling. The reactor must be purged of oxygen, and the water and monomer must be free of metallic impurities to prevent an adverse effect on the thermal stabiUty of the polymer. 

Industrial uses of L-ascorbic acid relate to its antioxidant and reducing properties. It is used as an antioxidant in the commercial preparation of beer, fmit juices, cereals, and caimed and frozen foods, etc. 

In addition to differences in thek methodology to extend the carbon chain, these manufacturers differ in thek syntheses of P ionone. P Ionone is commercially prepared via an acid-cataly2ed rearrangement of pseudoionone (26). This intermediate is manufactured on an industrial scale from either citral (27) or dehydro-hnalool (28) (21) (Fig. 5). 

The Bart reaction is successful with a wide variety of aromatic and heterocycHc amines. A variation in which an aromatic amine, in the presence of arsenic trichloride, is dia2oti2ed in an organic solvent (the ScheUer reaction) has also found wide appHcation. Both arsonic and arsinic acids can be prepared by the ScheUer reaction which often gives better yields than the Bart reaction with electron-attracting substituents on the aromatic ring. For the commercial preparation of 4-aminophenylarsonic acid [98-50-0] (arsaniUc acid), C HgAsNO, and 4-hydroxyphenylarsonic acid [98-14-6] C H AsO, the Bnchamp reaction is used ... 

Commercial preparation of sodium perborate tetrahydrate is by reaction of a sodium metaborate solution, from sodium hydroxide and borax pentahydrate, and hydrogen peroxide followed by crystallization of tetrahydrate (95). The tnhydrate and monohydrate can be formed by reversible dehydration of the tetrahydrate. 

Sodium perborate monohydrate, NaBO H2O or Na2B2(02)2(0H)4, 16.0 wt % active oxygen, is commercially prepared by dehydration of the tetrahydrate. The monohydrate has the same peroxyborate anion (7), as the higher hydrates and is the anhydrous sodium salt of this anion. Further dehydration results in decomposition of the peroxyborate. 

Miscellaneous Compounds. Among simple ionic salts cerium(III) acetate [17829-82-2] as commercially prepared, has lV2 H2O, has a moderate (- 100 g/L) aqueous solubiUty that decreases with increased temperature, and is an attractive precursor to the oxide. Cerous sulfate [13454-94-9] can be made in a wide range of hydrated forms and has solubiUty behavior comparable to that of the acetate. Many double sulfates having alkaU metal and/or ammonium cations, and varying degrees of aqueous solubiUty are known. Cerium(III) phosphate [13454-71 -2] being equivalent to mona2ite, is very stable. 

Cupric chloride or copper(II) chloride [7447-39 ], CUCI2, is usually prepared by dehydration of the dihydrate at 120°C. The anhydrous product is a dehquescent, monoclinic yellow crystal that forms the blue-green orthohombic, bipyramidal dihydrate in moist air. Both products are available commercially. The dihydrate can be prepared by reaction of copper carbonate, hydroxide, or oxide and hydrochloric acid followed by crystallization. The commercial preparation uses a tower packed with copper. An aqueous solution of copper(II) chloride is circulated through the tower and chlorine gas is sparged into the bottom of the tower to effect oxidation of the copper metal. Hydrochloric acid or hydrogen chloride is used to prevent hydrolysis of the copper(II) (11,12). Copper(II) chloride is very soluble in water and soluble in methanol, ethanol, and acetone. 

Copper Oxides. Coppet(I) oxide [1317-39-17 is a cubic or octahedral naturally occurring mineral known as cuprite [1308-76-5]. It is ted or reddish brown in color. Commercially prepared coppet(I) oxides vary in color from yellow to orange to ted to purple as particle size increases. Usually coppet(I) oxide is prepared by pytometaHutgical methods. It is prepared by heating copper powder in air above 1030°C or by blending coppet(II) oxide with carbon and heating to 750°C in an inert atmosphere. A particularly air-stable coppet(I) oxide is produced when a stoichiometric blend of coppet(II) oxide and copper powder ate heated to 800—900°C in the absence of oxygen. Lower temperatures can be used if ammonia is added to the gas stream (27-29). 

It is commercially prepared from benzaldehyde and hydrogen cyanide. Mandelonitrile is used by certain insects (tiger beedes, an African millipede) as a defense duid (38). After expelling the duid an enzyme catalyzes the conversion of mandelonitrile to benzaldehyde and HCN, which is usually fatal to the insect s enemy. 

Since many therapeutic enzymes are still derived from bacterial sources, FDA requirements can serve to make the commercial preparations more expensive. However, toxicological examination of each lot may not be necessary when the purification procedures yield reproducible preparations. 

Ethylene carbonate (l,3-dioxolan-2-one) is commercially prepared from ethylene oxide by the addition of carbon dioxide to ethylene oxide with either ammonium or alkaU metal salts as catalysts (87) ... 

Farmed animals tend to be subjected to compounds that can be classified more easily as drugs. In some cases, animals may encounter compounds in nature that have considerable limitations in inclusion in the diets of farmed animals. An example is the inclusion of zearalenone (Figure 1) and its derivatives in animal diets these have anabolic and oestrogenic properties " and are permitted to be used in some areas of the world but are prohibited from use in others, such as European Union countries. Thus this compound and its reduced isomers (zearalenols, zeranols) improve growth rates in animals but can cause reproductive problems, especially in pigs. Ralgro, which is a commercially prepared derivative of zearalenone, is used as an ear implant in beef cattle as a growth promoter in... 

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