Production of Intermediates

In 1930 Carothers and Natta prepared a number of aliphatic polycarbonates using ester-interchange reactions. These materials had a low melting point, were easily hydrolysed and did not achieve commercial significance. 

Carothers also produced a number of aliphatic linear polyesters but these did not fulfil his requirements for a fibre-forming polymer which were eventually met by the polyamide, nylon 66. As a consequence the polyesters were discarded by Carothers. However, in 1941 Whinfield and Dickson working at the Calico Printers Association in England announced the discovery of a fibre from poly(ethylene terephthalate). Prompted by the success of such a polymer, Farbenfabriken Bayer initiated a programme in search of other useful polymers containing aromatic rings in the main chain. Carbonic acid derivatives were reacted with many dihydroxy compounds and one of these, bis-phenol A, produced a polymer of immediate promise. 

Independently at the General Electric Company in America, work was being carried out in search of thermally and hydrolytically stable thermosetting resins. As a by-product from this work the research team at General Electric also produced polycarbonates from bis-phenol A so that by 1958 production of bis-phenol A polycarbonates was being carried out in both Germany and the USA. 

Today about 75% of the market is held by General Electric and Bayer with their products Lexan and Makrolon respectively. Other manufacturers are ANIC (Italy), Taijin Chemical Co., Mitsubishi Edogawa and Idemitsu Kasei in Japan and, since 1985, Dow (USA) and Policarbonatos do Brasil (Brazil). Whilst this market is dominated by bis-phenol A polycarbonates, recent important developments include alloys with other thermoplastics, polyester carbonates and silicone-polycarbonate block copolymers. 

As already indicated, the polycarbonates may be produced from a wide range of polyfunctional hydroxy compounds. In practice only the diphenyl compounds have proved of much interest and the only polycarbonate of commercial significance is derived from bis-phenol A 2,2-bis-(4-hydroxyphenyl) propane. 

---

It has been known since the early 1950s that butadiene reacts with CO to form aldehydes and ketones that could be treated further to give adipic acid (131). Processes for producing adipic acid from butadiene and carbon monoxide [630-08-0] have been explored since around 1970 by a number of companies, especially ARCO, Asahi, BASF, British Petroleum, Du Pont, Monsanto, and Shell. BASF has developed a process sufficiendy advanced to consider commercialization (132). There are two main variations, one a carboalkoxylation and the other a hydrocarboxylation. These differ in whether an alcohol, such as methanol [67-56-1is used to produce intermediate pentenoates (133), or water is used for the production of intermediate pentenoic acids (134). The former is a two-step process which uses high pressure, >31 MPa (306 atm), and moderate temperatures (100—150°C) (132—135). Butadiene,... 

Uses. (9-Nitrochlorobenzene is used in the synthesis of azo dye intermediates such as o-chloroaniline (Fast YeUow G Base), i9-nitroani1ine (Fast Orange GR Base), o-anisidine (Fast Red BB Base), o-phenetidine, and (9-aminophenol (see Azo dyes). It also is used in corrosion inhibitors, pigments, and agriculture chemicals. -Nitrochlorobenzene is used principally in the production of intermediates for azo and sulfur dyes. Other uses include pharmaceuticals (qv), photochemicals, mbber chemicals (qv), and insecticides (see Insectcontroltechnology). Typical intermediates manufactured from the para isomer are -lutioaruline (Fast Red GC Base), anisidine, -aminophenol, -nitrophenol, -phenylenediamine, 2-chloro-/)-anisidine (Fast Red R Base), 2,4-dinitrochlorobenzene, and l,2-dichloro-4-nitrobenzene. 

Uses. (9-Nitrotoluene is used in the synthesis of intermediates for azo dyes, sulfur dyes, mbber chemicals, and agriculture chemicals. Typical intermediates are o-toluidine, o-nitrobenzaldehyde, 2-nitro-4-chlorotoluene, 2-nitro-6-chlorotoluene, 2-amino-4-chlorotoluene (Fast Scarlet TR Base), and 2-amino-6-chlorotoluene (Fast Red KB Base). -Nitrotoluene is used principally in the production of intermediates for azo and sulfur dyes. Typical intermediates are -toluidine, -nitrobenzaldehyde, and 4-nitro-2-chlorotoluene. 

The majority (92% in 1988) of the butyraldehyde produced in the United States is converted into 1-butanol and 2-ethyIhexanol (2-EH). 2-EH is most widely used as the di(2-ethylhexyl) phthalate [117-81-7] ester for the plasticisation of flexible PVC. Other uses for 2-EH include production of intermediates for acryflc surface coatings, diesel fuel, and lube oil additives (24). 

Guideline 5. All of the intermediates produced by the elementary reactions must be consumed by other elementary reactions so that there will be no net production of intermediate species. 

In chemical equilibrium, the forward and reverse reaction rates are equal and there is no net production of intermediates. The equilibrium constant Keq is given as the ratio of reactants in equilibrium. For the elementary reaction shown in Eq. (21), we obtain... 

Figure 20.12 Different bubble sizes give different bed sizes for maximum production of intermediate.

Biphasic systems have been effectively used in several enzyme-catalyzed reactions, including peptide and alkyl glycosides synthesis, esterification and transesterification, alcoholysis, hydrolysis, and enantiomeric resolution [2, 24, 60]. Although application of this particular bioconversion system has been used for final products, it is mostly used in the production of intermediate compounds, particularly optically active ones, that can be used as building blocks in the pharmaceutical and food sectors [61-64]. Updated reviews have addressed this matter [2, 4, 24, 60-63], and examples of some representative recent applications of this methodology are given in Table 8.1). 

That products of intermediate oxidation level can be detected in the photocatalytic reactions of hydrocarbons and fossil fuels is also consistent with a surface bound radical intermediate . Photocatalytic isotope exchange between cyclopentane and deuterium on bifunctional platinum/titanium dioxide catalysts indicates the importance of weakly adsorbed pentane at oxide sites. The platinum serves to attract free electrons, decreasing the efficiency of electron-hole recombination, and to regenerate the surface oxide after exchange. Much better control of the exchange is afforded with photoelectrochemical than thermal catalysis > ) As before, hydrocarbon oxidations can also be conducted at the gas-solid interface... 

The yield of vinylated acetoxime is not high (to 10%). The formation of pyrroles, the products of intermediate 0-vinyloxime rearrangement (83KGS273), remains the major reaction pathway under these conditions. Although no 2-methylpyrrole was detected (GLC control) in a resin obtained by the thermolysis of O-vinylacetoxime (85), this pyrrole was found in a small quantity ( 5%) in the products of decomposition of O-vinylacetoxime in KOH/DMSO. 

Equation (3.47) calculates the tariffs that have to be paid for import of raw materials. Duty drawbacks are considered by charging tariffs only for raw materials required for production of intermediate (second line) and finished goods (first line) that are not re-exported. The amount of intermediates not re-exported is adjusted for those intermediates that are transformed into goods subsequently re-exported at the same site. The formulation rests on the assumption that only one raw material source is used per site and that if a required intermediate is available locally the local source is used. Prices are converted from the currency used by the raw material supplier to the currency of the consuming site. Same as with the valuation of finished goods for tariff calculation the full transport costs are included in the tariff value of the raw materials and intermediates. Import tariffs for intermediates imported from another site are calculated in equation (3.48). The formulation differs from the one for raw materials because the source of the intermediates is not predetermined and the transfer price does not contain transportation costs. The net volumes of the intermediates which are not re-exported are calculated by subtracting the quantities contained in exported products from the total quantity imported. A non-negativity constraint sets the value to 0 if the respective intermediate is not imported from site s. ... 

The reactions for the production of intermediates and dyes are carried out in bomb-shaped reaction vessels made from cast iron, stainless steel, or steel lined with rubber, glass (enamel), brick, or carbon blocks. These vessels have capacities of 2-40 m3 (ca 500-10 000 gallons) and are equipped with mechanical agitators, thermometers, or temperature recorders, condensers, pH probes, etc., depending... 

---