House procedure

Pioneering work on the desulphonylation of jS-ketosulphones was carried out by Corey and Chaykovsky - . This reaction was part of a sequence which could be used in the synthesis of ketones, as shown in equation (53). The main thrust of this work was in the use of sulphoxides, but Corey did stress the merits of both sulphones and sulphonamides for different applications of this type of reaction. The method soon found application by Stetter and Hesse for the synthesis of 3-methyl-2,4-dioxa-adamantane , and by House and Larson in an ingenious synthesis of intermediates directed towards the gibberellin skeleton, and also for more standard applications . Other applications of the method have also been madealthough it does suffer from certain limitations in that further alkylation of an a-alkyl- -ketosulphone is a very sluggish, inefficient process. Kurth and O Brien have proposed an alternative, one-pot sequence of reactions (equation 54), carried out at — 78 to — 50°, with yields better than 50%. The major difference between the two routes is that the one-pot process uses the desulphonylation step to generate the enolate anion, whereas in the Corey-House procedure, the desulphonylation with aluminium amalgam is a separate, non-productive step. 

Where no in-house procedures are available, are there appropriate and identified published standard practices or manufacturer s written instmctions available ... 

The second part of the scope refers to the kind of method used and makes clear that whether the method is an internationally recognized standard or simply and in-house procedure, it falls within the scope of ISO/IEC 17025. In specifying exactly what a laboratory is accredited for, the accreditation body must be careful to correctly detail the methods. So if sulfur is analyzed by ASTM D5453, the laboratory must have demonstrated its capability to follow the method as laid specified in the American Society for Testing and Materials standard, or any changes made by the laboratory must be documented and validated. 

Butadienes substituted with alkoxy groups in the 2-position, e.g., 2-ethoxy-1,3-butadiene,6 have been prepared from methyl vinyl ketone, but they required several conversions and a tedious spinning-band distillation to purify the product. This slight modification of the House procedure has been used to conveniently prepare 2-trimethylsilyloxy-l,3-butadiene from the readily available methyl vinyl ketone. This one-step procedure has provided large amounts of a new and reactive diene for Diels-Alder reactions, as illustrated in Table I. 

The overall process of method validation is illustrated in Figure I. However, the extent and scope of validation is governed by the applicability of the method. An in-house procedure requires a less exacting process than a method intended for multi-matrix and/or multi-laboratory use. For the latter methods, a full collaborative trial is necessary and is covered in Chapter 9. However, for many purposes validation is limited to either demonstrating that method performance criteria established during development are met under routine laboratory conditions and/or showing method equivalence (Figure 18). 

The products are subject to safety testing as per in-house procedure (refer to the relevant procedure). 

Properties such as refractive index, clarity, transparency, and effect of sunlight are determined according to ASTM D542 [156] and are usually measured by in-house procedures developed by polymer manufacturers. 

The syntheses of all four stereoisomers of the 1,3-diol diesters 117 comprised a total of 4 X 2 steps (Scheme 23). Moreover, the four initial reactions were described in the literature. These parameters were so reassuring that MLH did not ponder the alternative of another killing-two-birds-with-one-stone approach, akin to the one that had furnished the 1,5-diol diesters 116 (Scheme 22). The first transformation of the syntheses of Scheme 23 was the NaBHt reduction of the aldols 36a anti) and 36a (ent,anti) by an in-house procedure " and the LiBli reduction of the aldols 36b ent,syn) and 36b (syn) following another literamre protocol. The second transformation was the respective bis(trifluoroacetate) formation. It was realized by treatment with an excess of Af-methyl bis(trifluoroacetamide). The resulting 1,3-diol diesters 117 were applied cmde to the GLC column (Section 8.6, Fig. 16). 

Under the NAMAS (National Measurement Accreditation Service) quality system, detailed procedures are written by a particular analytical laboratory which apply only to the instrumentation in that laboratory. Unfortunately, these in-house procedures are not made available to the wider analytical community. However, in 1991, ISO technical committee 201 on surface chemical analysis (TC20I) was set up specifically to develop documentary standards for the most industrially developed surface analytical techniques. The standards written by this technical committee are targeted directly at the requirements of the average industrial user, and, since they are ISO standards, are available to any analyst upon request [ I ]. 

Measurement is by observing the increase in temperature of water in a calorimeter when a specimen heated to a specific temperature is plunged into the water. Tests are nominally performed on a cylindrical test specimen. In-house procedures exist, but at present there are no standard refractory methods for measurement of this property. 

---