Review of the Patent Literature

Some of the important and typical structural types patented by the various companies are discussed in this section. Generic structures are simplified and thus not necessarily those that appeared in the referenced patents. 

Stauffer (later Zeneca, now Syngenta) patented extensively after their initial discovery and were able to gain good intellectual property advantage over competitor companies, particularly in terms of important 2,4- and 2,3,4-substituted benzoic 

They were also granted a patent that covered cyclohexane diones coupled to heteroaroyl acids (e.g., 26-28, Fig. 4.3.4) with very broad scope [34], which made patenting rather difficult for companies following Zeneca. 

Pyridines and pyrimidines were patented separately, to complete an impressive array of protection for the heterocyclic triketones [35]. Nevertheless, after the first patent appeared regarding this novel substance class, most of the major companies started programs in the field. There were basically two strategies Some companies searched for novel diones that were at the time outside the scope of the Zeneca published patents, while other companies searched for novel aromatic acids. For example, Sandoz (now Syngenta) concentrated on the search for novel diones, and several compounds containing bicyclo[3.2.1]octane-2.4-dione, such as 29 [36, 37] and 30 [38], as well as the oxazinedione types (31) [39, 40], were important compounds for use in corn (Fig. 4.3.5). A collaboration between Sandoz and SDS Biotech has also led to the identification of proform triketones containing bicyclo[3.2.1]octane-2.4-diones for use in rice, such as benzobicyclon (9) [41]. 

Nippon Soda also initially investigated the dione portion of triketones, and patented extensively compounds containing bicyclo[4.1.0]heptane-2,4-diones such as 32-35 (Fig. 4.3.6) [42]. 

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G Santus, RW Baker. Osmotic drug delivery A review of the patent literature. J Controlled Release 35 1-21, 1995. 

Composite thermochromic pigments consist of three components a pH sensitive dye, a proton donor, which acts as the colour developer, and a hydrophobic, nonvolatile co-solvent. To achieve the desired effect the components are mixed in specific ratios and usually encapsulated to protect the system in subsequent applications. A review of the patent literature on these compositions has been published. ... 

The catalytic effect has been explained in terms of the activation of the anhydride by interaction with the amine to give a zwitterionic intermediate (47 Scheme 10) (B-68MI11501). Imidazoles have also been suggested as accelerators for anhydride cures (68USP3394105). A review of the patent literature (B-77MI11502) shows that several heterocyclic compounds are of interest as curatives for epoxy resins. 

Furfural has been used as a component in many resin applications, most of them thermosetting. A comprehensive review of the patent literature describing these uses is beyond the scope of this review. A few, selected recent patents and journal articles have been referenced. Resins prepared from the condensation products of furfural with urea (47), formaldehyde (48), phenols (49,50), etc, modified by appropriate binders and fillers are described in the technical literature for earlier applications, see reference 1, which contains many references in an appendix. 

G. Santus and R.W. Baker, Osmotic Drug Delivery A Review of the Patent Literature, J. Controlled Release 35, 1 (1995). 

Santus G, Baker RW. Osmotic drug delivery review of the patent literature. / Control Release 1995 35 1—21. 

A complete review of the patent literature related to reactive blending is beyond the scope of this volume. The reader is referred to the excellent volume by Utracki [I] where, in Appendix IV, one can find a chronological summary of Polymer Blend Discoveries and Development . 

The patent literature is filled with countless examples of potentially commercializable blends, many of which never reach commercial status. The published technical literature generally ignores the patent literature however, a wealth of information exists worthy of review. A comprehensive review of the patent literature is not possible, but examples will be noted to illustrate the diversity of potential applications involving polymer blends. 

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