Early Patent Literature

As we have shown in Section 4.6, emulsified oils are usually relatively ineffective antifoams for aqueous solutions despite possession of the properties necessary for participation in, for example, the bridging-stretching mechanism for antifoam action as described in Section 4.5.1. It is now widely accepted that this limitation derives from the stability of oil-water-air pseudoemulsion films. It is also now firmly established that the role of the particles concerns rupture of the otherwise metastable oil-water-air pseudoemulsion films [1, 22,43, 44, 70, 71, 98, 215]. Here we give an account of the evidence that has led to these conclusions after briefly summarizing the many examples of hydrophobic oil-hydrophobic particle mixtures described in the early patent literature, which in most cases predated any reference to the phenomenon in the scientific literature. 

Mechanistic studies of oil-particle antifoam synergy did not appear in the scientific literature until the mid-seventies [53, 67, 71, 207, 209] of the last century. Indeed only a few references to it appeared before 1970 [39, 106]. However, descriptions of many examples of mixtures of hydrophobic particles and oils have been appearing in the patent literature since the early fifties of that century. Examples of those early patents, filed before 1980, are listed in Appendix 4.1 as Tables 4.A1 through 4.A3. Here they are categorized as mixtures of hydrophobed mineral particles and silicone oils (Table 4.A1), mixtures of hydrophobed mineral particles and organic liquids (Table 4. A2), and mixtures of intrinsically hydrophobic organic particles and organic liquids (Table 4. A3). 

The finely divided nature of the particles is often stressed in these patents, and methods of milling are sometimes described [216]. Whenever particle size is quoted, it usually falls in the range of 0.001-1.0 microns. The preferred particle concentration in the oil ranges from 1% to about 30% by weight. 

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Claims of species containing more than two points of attachment to the surface postulated in early patent literature [MoC15 reacting with silica surface via five oxide bridges (57)] are probably unlikely considering both the stereochemical configuration and the accepted surface hydroxyl concentration on silica (4.6 hydroxyl/100 A2). The mode of interaction of the metal hydrocarbyl with the surface is confined to Reactions 2 and 3 with the remote possibility of a three-oxide attachment. 

Interesting work found in early patent literature deals with the use of dehydroalanine as an electrophile in the Michael addition of aminophosphinic acids, and diversification of the amino group appeared in the Pi position by coupling reactions [105]. This concept was extended by Vassifiou et al. by allowing a similar precursor (43) to participate efficiently in benzylation diversification reactions (Scheme 22) [106]. 

Additional examples of dendritic-type surfactants were reported in the early patent literature as hydrophobic core functionalized PAMAM dendrons [35,168]. For example, when the core was a 12 carbon chain, the first two generation PAMAM dendrons exhibited hydrocarbon solubility (TMF). 

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

The development of acrylic adhesives is well documented, although most of the publications are in the patent literature. Much early work was done by Bader and coworkers [4-7] at Degussa (Deutsche Gold- und Silber-Scheideanstalt vormals Roessler), and provides a good source for starting formulations. 

VI. Uses. During the latter part of the nineteenth century and the early part of the present century, PA was widely used as the main expl charge of projectiles and bombs. This is no longer true, Indeed PA per se is hardly used as an expl. Its current limited expl-related use is primarily in the preparation of Explosive D (Ammonium Picrate) and Lead Picrate. It also finds some use as an intermediate in the manuf of dyes. There is some patent literature on the use of PA as a catalyst for polymerizations. For example, PA is claimed as catalyst in polybutadiene polymerizations (Ref 40), and for the prepn of an isobutylene-5-methyl-1,3,6 hepta-trieie copolymer (Ref 38)... 

In recent years, there has been an explosive growth in pubhcations concerning LDHs in both academic journals and the patent literature. These reviews have attempted to cover work pubhshed up to early 2005, but many examples of excellent science have no doubt been excluded, either inadvertently or because of space limitations. 

The butadiene polymers represent another cornerstone of macromolecular stereochemistry. Butadiene gives rise to four different types of stereoregular polymers two with 1,2 linkage and two with 1,4. The first two, isotactic (62) and syndiotactic (25), conform to the definitions given for vinyl polymers, while the latter have, for eveiy monomer unit, a disubstituted double bond that can exist in the two different, cis and trans, configurations (these terms are defined with reference to the polymer chain). If the monomer units all have the same cis or trans configuration the polymers are called cis- or trans-tactic (30 and 31). The first examples of these stereoisomers were cited in the patent literature as early as 1955-1956 (63). Structural and mechanistic studies in the field have been made by Natta, Porri, Corradini, and associates (65-68). 

Recognizing then that many of the applications which have been proposed still fail because of early fatigue, it is still deemed useful to survey briefly claims of photochromic activity found in the recent patent literature. 

While carbon nucleophiles were suggested to be efficient in substitution for fluoride in the early patent,48 the first examples in the primary literature appeared in 1974.51-52 It is now clear that there are three reactivity classes of carbon nucleophiles (i) stabilized carbanions (from carbon acids with pKa < ca. 18) ... 

Considering the exceptional activity of liquid superacids and their wide application in hydrocarbon chemistry, it is not surprising that work was also extended to solid superacids. The search for solid superacids has become an active area since the early 1970s, as reflected primarily by the existence of extensive patent literature. 

Early oxidation hair dyes were used in solution form these have been replaced by cream- or gel-based formulas. The oil-in-water emulsions commonly used can be supplemented with auxiliary ingredients, such as polymers to improve combing ability, as well as other conditioning additives. Extensive patent literature is available on this point [35], Gel formulations may be based on alcoholic solutions of nonionic surfactants or fatty acid alkanolamide solutions, which form a gel when mixed with the oxidant. The type (emulsion or gel) and the basic composition of the preparation strongly influence dyeing [47], Different base formulations with the same dye content yield varying color depths and shading due to the distribution of the dye between the different phases of the product, interaction with surfactants, and diffusion from the product into the hair. 

There are many polymer chain modification reactions of different types that have been carried out on polymer melts processed in single and twin rotor extruders. This activity, (4-6) in the analysis of polymerization reactors, driven by market forces seeking to create value-added polymers from commodity resins, started in the mid-1960s in industrial research laboratories (7). Indeed much of the early work is to be found in the patent literature.1 Although in recent times more publications, both industrial and academic can be found in the open literature, there is still a good deal of industrial secrecy, because the products of reactive polymer processing are of significant commercial value to industry. Below we will deal briefly with two important examples of such reactions. 

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