Patents structurally modified

Whipple, W.L. et al. (2003) Structurally-Modified Polymer Elocculants. US Patent 6,605,674. Honig, D.S. et al. (2000) Design and development of the micropolymer system an organic microparticle retention/drainage system. Nord. Pulp Pap. Res. J., 15(5), 536-544. 

Numerous schemes have been explored in an effort to correlate the effects of modifying chemical substituents on a patent structure with their effects on the target property. That attributed to Professor Corwin Hansch of Pomona College, the most prevalent and easiest to understand, is based on ideas derived from physical organic chemistry. The basic problem can be illustrated using an HlV-1 protease" inhibitor as an example. 

A patent application from Merck Frosst, published in 1997, discloses CB2 selective compounds with modified core structures where the pyran oxygen is replaced by nitrogen, such as (342), which has a K of around 64 nM at CB2 and around 25,000 nM at CBi [217]. 

BODIPY fluorophores are a class of probes based on the fused, multi-ring structure, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (Figure 9.27) (Invitrogen) (U.S. patent 4,774,339). This fundamental molecule can be modified, particularly at its 1, 3, 5, 7, and 8 carbon positions, to produce new fluorophores with different characteristics. The modifications cause spectral shifts in its excitation and emission wavelengths, and can provide sites for chemical coupling to label biomolecules. 

Dawdy, T. H., Epoxy Modified Structural Adhesives Having Improved Heat Resistance, U.S. Patent 4,467,071 (1984). 

Sulfur, modified in its structure so as to become plastic, presents other problems as it can be a very ductile material. Reinforcement in the sense of load sharing may be effected by incorporating relatively ductile thermoplastic fibers. There is a commercial interest in using polypropylene fibers, and Bennett (10,11) has patented a process whereby woven polypropylene fibers are impregnated with asphalt or bitumen and then are coated on at least one side with a sulfur composition. The plasticized sulfur coating sticks to the base and makes the laminate flexible, weather resistant, and light reflecting. 

Fortunately the toxicology is clean for this slightly modified molecule, which, incidentally, is easy to synthesize with only six synthetic steps. The derivative structure and several other structures that were potential backups to the original antiepileptic were covered by the original patent application (i.e., the company already owns this NCE), but pain was not listed as an indication. This means that the company can now apply for a use patent for this chemical innovation. The target is old, the drug is old, but the label is new. This is a formula borrowed from car companies. 

The addition of a third component to the metal-alkyl is a widespread practice with MgCI2 catalysts in order to improve their performance and to control the polymer molecular structure. In ethylene polymerization the addition of modifiers (alkyl-halides, Lewis acids such as A1C13, halogens such as I2, and others) is rather limited and is principally used to modify the MWD (see Table 11 in Ref.53)). On the other hand, the addition of modifiers is almost indispensable to obtain satisfactorily stereoregular propylene polymers. The additives used for this purpose are generally electron donor compounds (Lewis bases) and a wide variety has been described in patent and scientific literature. 

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