CIP system

Other methods have been proposed for detecting chiral carbon atoms which do not rely on the CIP system, and which have been more convenient for some specific applications [108]. 

A CIP system includes pipelines, interconnected with valves to direct fluid to appropriate locations, and the control circuit, which consists of interlines to control the valves that direct the cleaning solutions and water through the lines, and air lines which control and move the valves. A programmer controls the timing and the air flow to the valves on a set schedule. The 3A Standards for CIP components, equipment, and installation have been developed. A simple CIP system circuit is shown in Figure 11. 

The stereochemical designations employed for organometallic complexes follow an extension of the CIP system2. In all cases, the chiral metal atom has a higher atomic number and thus receives priority. The main feature of this extension of the CIP system concerns treatment of polyhapto ligands such as cyclopentadienyl ... 

Fig. 2.49.4. View of a valve inside the condenser (all shelves in their lowest position). The condenser coils are seen in the background. In front to the right is a part of the CIP system. The seal of the valve can be replaced in the position shown.

There are many procedures to determine the chirality sense of a stereomodcl, the best known being the R and S descriptors of the Cahn-Ingold Prelog (CIP) system. 

The Cahn-Ingold -Prelog (CIP) System 1.1.5.1. Historical Background... 

The CIP system evolved in four steps by a combination of logical reasoning and a pragmatic trial and error approach. The evolution was driven by the practical necessity to describe the vast number of known molecules and an impressive array of brain-teasers proposed by clever chemists. 

There are wide-spread misconceptions about the scope and possibilities of the CIP system and other systems based on it or derived from it. It is most often criticized for its inability to show up analogies or relations among sets of analogous but nonstereoisomeric compounds. A few examples are discussed in order to demonslrate that this criticism is unfounded and even likely to lead to misuse and confusion. 

Within the CIP system these general criteria are expressed as five Sequence Rules. These are... 

Mislow and Siegel11 criticized the CIP system, inter alia, by totally denying symmetry-adaptation of it. The above enumeration, however, should suffice to demonstrate that this disqualification is certainly not appropriate for stereogenic units of tpye 1. Their comments on "pseudoasymmetric centers 11 unfortunately use varying viewpoints and make erroneous assignments of descriptors. The point at issue, which is of fundamental significance, is best explained by the examples 1, 2, and ent-2, also used by these authors. 

In the areas of coordination and metalorganic compounds the CIP system was adopted in part (Sequence Rules), but a variety of special conventions mainly concerning constitution and descriptor assignment rules for stereogenic centers with more than four ligands have emerged. An excellent review is available1, and here only those types of compounds relevant to this volume are discussed. 

The hard, general description is equivalent to applying the CIP system. The necessity to separate the aspects of enantiomerism (topographic description, absolute configuration) and diastere-omerism (geometric description, relative configuration) first arose practically in order to distin-... 

As soon as carbon-bound substituents, with the exception of methyl (and perhaps ethyl) or tertiary centers arc admitted, the distinction between backbone and substituents becomes ambiguous. This problem arose in the 1950s, before the advent of the CIP system, in conjunction with early studies of C-C bond formation by addition to carbonyl groups. At that time,... 

Assessing stereoselectivity in terms of descriptors is very simple as it merely involves the CIP specification of absolute and/or relative configurations of the stereoisomeric products of a reaction. This is just the task for which the CIP system was developed. The addendum of extraction of relative configuration by the like/ unlike (// ) description1 is explained in Section 1.1.8.1. 

Its extension to enantio- and diastereo/opos-differentiating reactions is straightforward. Enan-tio- and diastereomer-differentiating reactions do not require special rules the CIP system itself suffices for their description. 

CIP systems are commonly used to eliminate environmental and personnel exposure to the contaminant. They are effective when the shutdown and disassembly of equipment in production would impact manufacturing efficiency. They are also used to improve the consistency and reproducibility of the cleaning process. 

Computer control of CIP systems is common and programmed recipes can help control the consistency and quality of the cleaning procedure. Validated computer systems used for CIP should be considered. 

Chamber clean-in-place (CIP) system Steam sterilization... 

Figure 7.18 Typical CIP system. Source By courtesy of Krones (UK) Ltd.

---