Initial Version of the Process

Once all the information has been collected (Chapter 3), an initial version of the process is drawn up [Trotta 1997, Gilles 1998, Frey 2000, Kussi 2000a]. In general, it has been found usefid to adopt the following procedure  

2 Drawing up an Initial Version of the Process 285 Starting material Air 

There is at present no method which will result in the best version of the process being invariably chosen at the outset and there will presumably not be one in the future either [Blaft 1985, Kaibel 1989, Scholl 1995], Finding the optimum version of a process requires not only knowledge and experience but also a considerable creativity, since the number of possible ways of carrying out a given task is almost infinite and many of the rules can still not be quantified, that is, they are not accessible to algorithms [Erdmann 1984]. This is demonstrated in the following example. 

Z = number of alternative arrangements N = number of components S = number of separation processes 

If all components can be separated by distillation, (N-1) = 4 separation columns are necessary, which can be arranged in 14 different ways. If a second separation process (e.g, an extraction if the ester, alcohol, and water form azeotropes) must be added, this already results in 224 possible arrangements. If the number of possible reaction procedures (e.g., batch [Uhlemann 1996]/continuous, gas/liquid, ion exchar er/mineral acid) is also taken into consideration, there will be an almost infinite number of ways of carrying out the process (a so-called combinatorial explosion). 

---

Tools used in Drawing up the Initial Version of the Process... 

Baizer 337) and Danly 338 - 341) wrote many detailed reports on the development of this synthesis from the early laboratory experiments to the production stage. The process was initially carried out in divided cells but was subsequently made much more cost-effective by changing over to undivided cells. Some important characteristic data of the two versions of the process 341 are summarized in the table below. 

The contribution to the overall scenario is summarized through the three process steps shown in Fig. 3.18. Suppose that the developer has finished processing the initial version of the extruder functional zones in the flowsheet editor. This information is sent, under the control of the process engine, to MOREX (step 1). MOREX receives the extruder configuration, along with material and process parameters via XML. The engineer, then, starts the... 

This figure represents the clear interface of data and subsystems within the initial version of the software (to the left) but shows how this structure is corrupted due to the evolution process. This result has major implications on the comprehensibility and future adaptability of the software module. 

The SCALE system consists of a driver module, control modules, functional modules, and a data base. The components of the initial version of the SCALE system are shown in Fig. 1. In the SCALE system, the user selects an analytical sequence of combined data processing and systems analysis which is characterized by the type of analysis to be performed and the geometric complexity of the system being analyzed. The user then prepares a single set of input for the control module corresponding to this standard analytical sequence. The control module input is in terms of easily visualized engineering parameters specified in a simplified freeform format. The control module uses this information to derive additional parameters and prepare the input for each of the functional modules in the analytical sequence. 

Initial production of the dimethyl terephthalate started with the oxidation of -xylene to terephthaUc acid using nitric acid both companies reportedly used similar technology (43—45). Versions of the nitric acid oxidation process, which has been abandoned commercially, involved the use of air in the initial oxidation step to reduce the consumption of nitric acid (44,46,47). The terephthaUc acid was then esterified with methanol to produce dimethyl terephthalate, which could be purified by distillation to the necessary degree (48). 

The Pictet-Spengler reaction has mainly been investigated as a potential source of polycyclic heterocycles for combinatorial apphcations or in natural product synthesis [149]. Tryptophan or differently substituted tryptamines are the preferred substrates in a cyclocondensation that involves also aldehydes or activated ketones in the presence of an acid catalyst. Several versions of microwave-assisted Pictet-Spengler reactions have been reported in the hter-ature. Microwave irradiation allowed the use of mild Lewis acid catalysts such as Sc(OTf)3 in the reaction of tryptophan methyl esters 234 with different substituted aldehydes (aliphatic or aromatic) [150]. Under these conditions the reaction was carried out in a one-pot process without initial formation of the imine (Scheme 86). 

Ketcha and Wilson reported the solid-phase version of the classic Nenitzescu indole synthesis in a process involving initial acetoacetylation of ArgoPore-NH2 resin with diketene to afford a polymer bound acetoacetamide <00TL6253>. Formation of the corresponding enaminone 102 via condensation with primary amines in the presence of trimethylorthoformate followed by addition of 1,4-benzoquinones 103 leads to formation of polymer bound 5-hydroxyindole-3-carboxamides 104 which could be cleaved from the resin using TFA yielding the indoles 105. 

IG-Hydrogenation An advanced version of the Bergius process in which the initial product of coal gasification is refined by centrifugation and the slurry residue is carbonized. 

---