INORGANIC POLYMERS CHALLENGE TO THE CARBON-CARBON BOND For utility, the carbon-carbon bond of organic polymers will remain hard to beat; but boron-phosphorus, boron-nitrogen, and others are entering the lists
DR. KENDRICK R. EILAR and DR. ROSS I. WAGNER
American Potash & Chemical Corp., Whittier, Calif.
During the past decade the efforts of many chemists have been devoted to the challenging problem of creating new polymers based on inorganic chemical structures. Motivating these efforts are the ever-rising needs for new materials that can withstand high temperatures and other extreme conditions. The outstanding success of polymer chemists in developing organic polymers of tremendous variety and utility serves as a guiding light, showing what can be accomplished with macromolecules and defining general methods of synthesis, characterization, and application of polymers. 138
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This same light, however, shows the weaknesses and limitations to be expected of organic polymers; and, together with the rapidly expanding knowledge and interest in inorganic chemistry, it sparks the imagination and stimulates the search for new types of polymers that might go beyond these apparent limitations. Largely because of this background, inorganic polymer research draws on the ingenuity of organic and inorganic chemists alike and, in fact, bridges the two fields of chemistry. Although the term "inorganic polymer" has no precise definition and means different
things to different people, our discussion will focus on research bearing on inorganic and partially inorganic materials having the character of plastics, resins, elastomers, adhesives, and fluids. Even within this limited definition, research on inorganic polymers is not really new. Polymeric forms of phosphonitrilic chloride were discovered by Liebig and Wohler in 1834, and in 1897 Stokes reported the preparation of a so-called "inorganic rubber" form of phosphonitrilic chloride, (PNC1 2 ) X . Numerous other references to inorganic polymers can be found in the literature of the past half century. But in recent years the search has been intensified and greatly expanded in scope to develop useful materials from systems of known potential, such as the phosphonitrilic polymers, and to discover entirely new bonding systems based on modern theory. A substantial aspect of this work is, of necessity, basic research aimed at broadening our understanding of chemical bonding and the- interrelationship of physical properties with chemical structure. Inorganic polymer research has scored one major success thus far. This is the siloxane, or silicone, family of polymers developed in the 1940's and now standard items of commerce. More recent research has not yet led to commercialization of any other entirely new inorganic polymer systems, but encouraging progress is being made on several fronts, such as phosphorus-nitrogen, boron-phosphorus, coordination, and new silicon-based polymers. The Approaches
Vary
Logically enough, one of the most important approaches being pursued is further study of silicone-type polymers. In addition to modifying and improving the basic silicone structure, scientists are systematically studying
C&EN chemical science series
the effects of replacing the silicon or oxygen atoms, or both, by other elements of groups II, III, IV, V, and VI. A somewhat different line of approach, not necessarily based on analogy with the silicones—although not actually different in principle—has led to studies of polymers that might theoretically be formed by covalent bonding between any two polyvalent elements. Among such covalent bond combinations as, for example, siliconsilicon, phosphorus-phosphorus, boronboron, aluminum-nitrogen, and titanium-nitrogen, a great many new types of compounds have been synthesized, and knowledge of chemical bonding has been greatly expanded. Since high thermal stability is one of the primary goals, one can also approach the problem through thermodynamic theory. Thus the skeletal atoms of a polymer system should be selected so as to form bonds as strong as, or stronger , than, carbon-carbon bonds if the thermal stability is to exceed that of organic polymers. Potential candidates might be berylliumoxygen, boron-oxygen, boron-carbon, and arsenic-oxygen, to name but a few. Yet, perhaps a more important criterion for thermal stability than the thermochemical bond energy is the lack of a kinetically favorable reaction path by which the polymer system can degrade. Bonding in inorganic molecules is not yet so thoroughly understood as in organic compounds. While s-p sigma bonds and sigma-pi multiple bonds are the general rule in organic molecules, in inorganic systems there are further possibilities, involving d-orbital TTbonding and other less well recognized interactions of the bonding electrons. Studies of new bonding principles have led to (or in many cases, resulted from) new types of compounds, such as the metallocenes and boron hydrides. Coordination polymers constitute one broad category of research being pursued in this connection.
BOROPHANE COMPOUNDS. Dr. Marvin Goodrow, research project chemist at American Potash & Chemical, studies preparation of borophane derivatives. By using a tertiary amine or phosphine to block cyclization, linear borophane polymers can be obtained, although method for complete control of the process has not yet been worked out
Although very many good approaches are available, the difficulties in inorganic polymer research are extremely large. Many inorganic systems show a tendency to polymerize, in the sense that two or more units combine to form stable multiunit molecules. But in the vast majority of known cases, this tendency is strongly directed to the formation of small cyclic molecules—dimers, trimers, tetramers, and other low polymers. In the development of silicone polymers, for example, the products first obtained and characterized were small cyclic polymers containing two to six siloxane units. In present production of silicone polymers, a substantial portion of the product still turns up in the form of cyclic low polymers, and the upper temperature of utility for higher silicone polymers is limited (in the range of 350° to 450° C.) by
depolymerization to the volatile, cyclic low polymers. While means have been found to circumvent the tendency of the silicones toward cyclization, many other inorganic polymer systems seem quite resistant to such control. In going the apparently short step from siloxanes to thiosiloxanes, where the silicon atoms are connected through sulfur atoms instead of oxygen atoms, the tendency to form cyclic dimers and trimers is found to be very strong and, in fact, has not been overcome. The situation with other inorganic systems is similar, varying only in degree. Not only does the tendency of inorganic "monomelic" units to form low polymers impede the formation of high polymers—it also hinders the study of monomer units per se and of reaction techniques and mechanisms whereby they might be polymerized. AUG. 6, 1 9 6 2 C & E N
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Are bond energies most important in thermal
stability?
That bond energies are not the most important factor in thermal stability is illustrated by silicone polymers. The silicon-oxygen bond (about 110 kilocalories per mole) is stronger than the silicon-carbon bond (about 64 kilocalories per mole) in terms of thermochemical bond energy; but linear polysiloxanes, on heating above 350° C , yield cyclic siloxanes, indicating that siliconcarbon bonds remain intact while silicon-oxygen bonds are broken. Explanation for such phenomena usually can be found in reaction mechanisms whereby bond rearrangement occurs through a transition state which, in effect, lowers the energy barrier relative to that which would be required for a direct thermal rupture. The drawing shows a possible sequence for depolymerization of a polysiloxane
One circumstance which makes possible the wide range of organic polymers and their facile production is the carbon double bond with another carbon or with oxygen. By virtue of this property, it is relatively easy both to produce and to study organicr monomers, and to convert them to polymers by reactions that open the double bonds to form polymer-linking bonds ("addition" polymerization). Outside of the first row elements—carbon, nitrogen, and oxygen—multiple bonds of the p-7r type are rare. On the other hand, multiple bonds involving p-?r d-7r orbitals are probably more widespread than is generally understood, but these usually do not react by addition polymerization. Hence, it is generally not possible to isolate an inorganic monomer corresponding to monomers of organic addition polymers in order to study its polymerization. Silicon INTRIGUING SUBSTANCE. Prof. John C. Bailar, University of Illinois, and students, Dr. Yong Shim (right) and Gerald Tennenhouse, examine beryllium chelate monomer, in bottle, and polymer obtained by condensation of the monomer with ethylene glycol. Although inorganic polymers can be defined as those that don't have carbon-carbon bonds in the backbone, they may still contain organic groups
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Polymers
As indicated earlier, research on silicon polymers is very active and widespread. Consequently, it has been reviewed extensively and we shall mention here only a few highlights of this research.
Linear and fused ring borophane polymers can be made
The triborophane B3P3 ring is a nonplanar chairform structure, similar to that of cyclohexane
Linear borophane polymers are the open-chain analogs of the cyclic trimer and tetramer
Three-dimensional network borophane polymers can be prepared, but this structure is very rigid and brittle. Strength is greatly improved by incorporating some difunctional units to provide a tittle flexibility at the molecular level
At the General Electric laboratories, long a leader in this field, Dr. J. F. Brown and co-workers recently found that trifunctional silicon monomers, RSiCl 3 , could be polymerized in a stereoregular manner to give ladder-like linear polymers of a onedimensional network structure. They produced the syndiotactic doublechain polymer of phenylsilsesquioxane by base-catalyzed rearrangement of cyclic low polymers in the presence of a small quantity of solvent. These polymers, with molecular weights up to 200,000 without branching and around 4,000,000 with branching, do not melt on heating but form good films by solvent deposition, and they appear very promising for high-temperature coating applications. In other active research at General Electric, silicone copolymers incorporating phenylboron units are being studied while, in Russia, K. A. Andrianov and co-workers are systematically synthesizing and studying polymers in which a backbone corresponding to various silicate minerals, ( ~ M 1 - 0 - M 2 - 0 - ) t t , is "clothed" with organic substituent groups attached to the metallic atoms ( M ) . Elements of most interest in the back-
bone structure, besides silicon, are aluminum, titanium, boron, and phosphorus. One product, with silicon and titanium in the backbone, and trialkylsiloxy side groups attached to the titanium atoms, exhibits high elasticity while another, with silicon and aluminum, is not fusible but is soluble in organic solvents. Metallosiloxanes in which M 2 is a divalent metal are much less stable than those in which M 2 is trivalent, tetravalent, or pentavalent, according to Dr. E. D. Hornbaker and Dr. F. Conrad of Ethyl Corp. They prepared polymers having tin ( I I ) , lead ( I I ) , magnesium, copper ( I I ) , zinc, and mercury ( I I ) , and found a proclivity for the polymer to decompose into polysiloxane and the metal oxide. Although cross-linked silicone resins, like other silicone polymers held together entirely by silicon-oxygen bonds, depolymerize to cyclic low polymers at 350° to 450° C , the introduction of phenylene units in the network linking structure appears to suppress depolymerization. According to L. W. Breed and W. J. Haggerty at Midwest Research Institute, resins prepared by controlled hydrolytic polymerization of p-pheny\ene-bis-
( d i e t h o x y m e t h y l s i l a n e ) , CH 3 Si( O C 2 H 5 ) 2 - C 6 H 4 - S i C H 3 ( O C 2 H 5 ) 2, and related compounds, cure to infusible products, some of which show no visible decomposition at temperatures as high as 500° C. Thermogravimetric analysis indicates that some weight loss does occur at lower temperatures, but this may be limited to less than 20% at higher temperatures. As a rule, compounds containing silicon-nitrogen bonds are readily hydrolyzed, but Dr. E. G. Rochow at Harvard showed that the hydrolytic susceptibility of silazanes can be reduced by appropriate configurations and can perhaps be made inconsequential. He has prepared from dimethyldichlorosilane and ethylenediamine both ladder-type and cross-linked polymers which can be stabilized by coordination with metal ions such as C u + 2 and Be+ 2 . Other metal ions of varying ionic volume, coordination number, bond angles, and electron acceptor strength may further enhance the stability of these polymers. Boron Polymers Polymers having boron in the backbone have been the object of numerous AUG. 6, 1962 C& EN
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recent studies, stemming largely from the fact that boron forms strong covalent bonds with such elements as carbon, nitrogen, oxygen, and phosphorus. Attempts to develop polymers based on the boron-oxygen bond, one of the strongest covalent single bonds known, and on the boron-carbon linkage, also very strong, have been eased by the synthetic approaches available. But the vulnerability of the boron-oxygen moiety to hydrolysis and of the boron-carbon structure to oxidative attack have thwarted the development of practical products. Interest in boron-nitrogen bonded polymers arises from the properties of boron nitride and the borazines. The common form of boron nitride is a sheet polymer, similar in many ways to graphite, thermally stable to about 2000° C , and fairly stable to hydrolysis and oxidation. The cubic form of boron nitride, the boron-nitrogen analog of diamond, was synthesized in 1957 by Wentorf at General Electric. This material, termed "Borazon," is also highly stable. The B 3 N 3 ring in certain substituted borazines, (RNBR') 3 , is thermally stable to about 500° C. Attempts have been made to translate these properties into workable linear —B—N— polymers. The best results yet reported are probably those of Dr. W. Gerrard, who recently prepared a linear —B—N— polymer stabilized by large substituent steric factors, but the properties and potential of this material are not yet clear. Efforts to p u t together polymers made up of borazine rings have been somewhat more rewarding. Dr. Gerrard and Dr. M. F. Lappert at Northern Polytechnic, London, and Dr. A. L. McCloskey and co-workers at U.S. Borax have obtained resinous polymers in which borazine rings are linked together through imino groups ( - N — ) , while chain polymers in
I
R which the rings are linked directly together have recently been synthesized in our laboratories at American Potash. These various products, although stable to moderately high temperatures (350° to 500° C ) , are generally brittle, lack toughness, and do not have great resistance to oxidation or hydrolysis. Phosphorus, the second row relative of nitrogen, forms bonds with boron that are analogous to the boronnitrogen bond, but which are different 142
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Phosphonitrilic geometry resembles that of butyl rubber
The P8N8 phosphonitrilic trimer ring is almost, but not quite, planar, and all of the phosphorus-nitrogen bonds are equivalent. The 8-membered tetramer ring is similar but more puckered, and it is thermodynamically more stable
The phosphonitrilic linear polymer probably has still wider bond angles than the cyclic tetramer. Geometrically, it is not unlike the polyisobutylene molecule of butyl rubber
from the latter in three important respects: Phosphorus is a larger atom than nitrogen, it has bonding d-orbitals available, and it exhibits a much lower tendency to form p-w double bonds. Thus, while the boron-nitrogen system readily forms a benzene-like ring in which the bonds have a significant degree of double-bond character, the boron-phosphorus system seems reluctant to form such a configuration. Instead, it forms a "saturated" ring, (R 2 PBR' 2 ) 3 , more like that of cyclohexane. These phosphinoborine, or "borophane" ring compounds, first described by Dr. Anton Burg and Dr. R. I. Wagner at the University of Southern California in 1953, exhibit a lack of reactivity in keeping with "saturated" character. Although an electronic structural drawing requires placement of a formal charge on each ring atom in the manner of a phosphonium borohydride, the boron substituents manifest little or none of the reactivity
normally associated with boron hydride or halide functions. This behavior is explained in part by the tetracoordinate condition of each ring atom, which satisfies the reactive vacant orbital of boron observed in its tricoordinate compounds. Dr. Burg adds another factor, based on analysis of the observed bond angles, bond lengths, and infrared absorption frequencies, which indicate that the phosphorus d-orbitals overlap the boron substituent bonding electrons, further enhancing the stability, or unreactivity, of the triborophane molecule. Borophane cyclic trimers of the above formula are prepared from a monomeric phosphine borane coordination compound by reactions which should yield a monomer: A
F^HPrBHs — > • H2 -f- R2PBH2 R2nPlBXR2
-HX ^ R2PBR2
But except for the completely phenyl-
Boron nitride's common form is a sheet polymer
Boron nitride is an indefinitely extended polymer, twodimensional or planar in the common white form, threedimensional in the diamond-like structure, Borazon. In effect, it is a completely interlinked polymer of a hexafunctional B3N3 (borazine) ring unit
i
N-R I
B I
N-R i
Here, trifunctional borazine ring units are interconnected in a resinous polymer by difunctional imino groups
substituted borophane, Ph 2 PBPh 2 , the monomer is not observed, and only the cyclic dimer, trimer, or tetramer are found. If conditions could be imposed to block cyclization, it should be possible to produce linear borophane polymers. Pursuing this line of approach at American Potash, Wagner found that by using a tertiary amine or phosphine to block cyclization, linear polymers could indeed be obtained. But complete control over the process has yet to be gained, since the monomer cannot be isolated and must be polymerized in situ. A small, catalytic quantity of amine promotes fewer and longer chains, but allows most of the monomer units to go unblocked so that they end up as cyclic trimer and tetramer. A large quantity of amine improves the yield of linear polymer, but it starts more chains and holds down their molecular weight; and it still does not entirely prevent cyclization. Linear polymers with molecular
If the functionality of the borazine ring, B3N8, is reduced to two by blocking four positions with unreactive hydrocarbon groups, a linear linked-type polymer can be produced
By trying various combinations of substituents, Gerrard has shown that linear polymers having a boron-nitrogen backbone can be prepared
weights of 5000 to 15,000 have been produced. Those with small alkyl groups on phosphorus are thermoplastics of relatively high crystallinity, and they can be drawn into fibers or pressed into films. The polymers probably are coordinated at one end with an amine or phosphine molecule and at the other end with a reactive BE[3 unit. This situation permits a mechanism for degradation, allowing depolymerization to occur at 200° to 250° C. If means can be found to block this degradation path, the thermal stability of the polymers might be raised considerably. As with the borazines, attempts are also being made to produce borophane polymers having linked or fused ring systems. This approach has led to thermoset resins, which are being tested for use in glass-reinforced laminates. The network polymers are formed by elimination of two molecules of hydrogen from RH 2 P:BH 3 to give (RPBH) W , or by polymerization
of the borane adducts of difunctional phosphines such as H 3 B:PHCH 3 C 3 H 6 CH 3 HP:BH 3 to give triborophane rings interconnected by alkylene or arylene groups. Progress to date is encouraging and structurally strong laminates having heat distortion temperatures above 250° C. have been obtained so far. The higher group V elements, arsenic and antimony, also form boron compounds of the type R 2 MBH 2 . The arsenic derivatives are polymeric but depolymerize easily, while the single known antimony derivative is apparently unpolymerizable. Boron forms several types of boronto-boron bonds. The single covalent boron-boron bond appears to have moderate thermal stability, but it is easily hydrolyzed or oxidized and offers little potential for extension to (— B—B— ) n polymers. In the higher boron hydrides, "multicenter" boronto-boron bonds exist along with boronhydrogen-boron bridge bonds. The AUG.
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Here are some polymers
that have been prepared
Chelate polymer prepared by Dr. C. S. Marvel, having a molecular weight over 10,000 and stable to about 300° C. in air. Various metals have been tried in combination with a variety of polymeric Schiff bases, jS-diketones, and other chelate-forming configurations
major practical interest in such compounds has been concerned with their application as high energy fuels, but the resulting research has turned up some derivatives of surprisingly high thermal stability (greater than 400° C ) . Olin Mathieson chemists, Burg, and others have made some efforts to turn these properties to advantage in polymer synthesis. But a great deal more basic research on the nature and reactions of the boron hydrides must be done before useful polymers are likely to emerge. Phosphorus
Polymers
Aside from silicon and the first row elements, more research efforts are
focused on phosphorus and its compounds than on any other category. Most intriguing here are the phosphonitrilics. In these compounds, of the general formula (R 2 PN)„, the backbone bonding consists entirely of phosphorus to nitrogen bonds, between trivalent, dicoordinate nitrogen on the one hand and pentavalent, tetracoordinate phosphorus on the other. They are of great interestboth theoretical and practical—because as a class they exhibit high thermal stability, they have high polymeric forms which are elastomerie, and have cyclic forms which constitute rare examples of aromaticity in a completely nonorganic system. The reaction of ammonium chloride
Suggested Additional 1. Barth-Wehrenalp, G., "Inorganic Polymer Chemistry Points Way to High Temperature Plastics," Chem. Eng., 118 (October 1961). 2. Gefter, E. L., "Organophosphorus Monomers and Polymers/' Glen Ridge, N.J. Associated Technical Services, Inc., 1962. 3. "Inorganic Polymers" (International Symposium), Special Pub. No. 15, The Chemical Society, London (1961). 4. Paddock, N. L., "Phosphonitrilic Derivatives—Aromatics Without Carbon," Res. Appl. Ind. 13, 94 (March 1960).
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Reading
5. Paddock, N. L., Searle, H. T., "The Phosphonitrilic Halides and Their Derivatives," in Advances in Inorganic Chemistry and Radiochemistry, Vol. 1, p. 347, New York, Academic Press, 1959. 6. Rochow, E. G., "Chemistry of the Silicones," 2nd ed., New York, John Wiley & Sons, 1951. 7. Shaw, R. A., "Inorganic Polymers," Soc. Chem. Industry, Monograph No. 1 3 ( 1 9 6 1 ) . 8. Stone, F. G. A., Graham, W. A. G., Eds., "Inorganic Polymers," New York, Academic Press (in press).
Silazane ladder polymers and their coordination with metal ions, under study by Dr. E. G. Rochow at Harvard University
with phosphorus pentachloride leads to a mixture of polymers of the general formula (PNCl 2 ) n . Along with the cyclic trimer and tetramer, larger cycles up to n = 17 have been recognized, and open-chain forms of a moderate degree of polymerization are also usually present in the product mixture. On heating the mixture or any of its components to 250° to 350° C , ring-opening takes place in the cyclics and the fragments polymerize to higher linear polymers. Heating at higher temperatures reverses the process, leading back to the cyclic compounds. The properties of various species identified in these processes range from the crystalline lower cyclics to oils, waxes, gums, elastomers, and infusible solids. The elastomer is of special interest because it is inorganic and is thermally Stable to above 300° C. Physical Studies of different samples indicate molecular weights from 20,000 to 80,000 and show that the polymer molecule bears close kinship to that of natural rubber. But while its physical properties and thermal stability are good, it cannot be used per se in practical applications because of its susceptibility to hydrolysis. Replacement of the chlorine atoms with less easily hydrolyzed substituents is the subject of continuing research in a number of laboratories. Replacement by amines and other nucleophilic groups is being studied by Dr. Therald Moeller at the University of Illinois, Dr. M. Becke-Goering at Heidelberg, and others. Dr. Charles Haber and David Herring at the Na-
Phenylsilsesquioxane ladder polymer prepared by Dr. J. F. Brown and coworkers at General Electric
val Ordnance Laboratory, Corona, Calif., have prepared the phenyl analogs, [ (C 6 H 5 ) 2 PN]3,4, but have not yet succeeded in obtaining a high molecular weight linear polymer. Their co-workers have recently reported preparation of the trifluoromethyl analogs. These and other studies may well lead to thermally and hydrolytically stable phosphonitrilic elastomers. Meanwhile, the linked-ring approach to resinous polymers has been pursued by Dr. R. G. Rice and coworkers at General Dynamics. Using hydroquinone as a linking unit, they have developed resins in which the phosphorus-nitrogen trimer or tetramer rings are interconnected in a network through P - 0 - C 6 H 4 - 0 - P units. The products are said to be hydrolytically stable, flame-resistant, and serviceable at 260° C. continuously, or up to 540° C. for short periods. Other types of polymers based on the phosphorus-nitrogen bond are possible besides those of the phosphonitrilic type. For example, Dr. H. W. Coover at Tennessee Eastman and Dr. P. R. Bloomfield at Artrite Resins have prepared polyphosphonamides of the general formula
Approaches to still other types of phosphorus polymers are mostly concerned with compounds involving phosphorus-to-oxygen bonds, phosphorus-to-carbon bonds, and combinations of these. Condensed aromatic phosphates of the type
have been described by workers at Tennessee Eastman, Du Pont, Artrite Resins, in Russia, and others. Monsanto chemists—Dr. John van Wazer, Dr. M. L. Nielsen, and several of their co-workers—are studying phosphorusoxygen, phosphorus-nitrogen, and phosphorus-carbon polymers on a rather broad front, using a variety of synthetic approaches, including molecular reorganization. In view of the widespread research efforts, the myriad possible combinations, and their outstanding potential properties, it seems certain that phosphorus is destined to play an increasingly important role in polymers. Few elements in the periodic table have been overlooked in the search for new inorganic polymers having unique properties. Variations of the approaches described in the foregoing discussion have been applied to most of the multivalent elements and even to polymers depending on halogenbridge bonds for linkage. But for the most part, oxygen and nitrogen are the workhorse linking units, for good and obvious reasons. For example, Dr. W. G. Woods at U.S. Borax has prepared linear polymers of moderately high molecular weight and good thermal stability (but poor hydrolytic stability) in which the repeating unit is —Al—O—. Dr. A. W. Laubengayer
(-fr) by thermal polycondensation of phosphonic diamides, with evolution of ammonia. The products are flame resistant, but they do not have exceptional thermal or hydrolytic stability.
FLIGHT HAZARD. Space flight requirements provide one of the great impulses for inorganic polymer research. Cracked windshield panel, caused by aerodynamic heating during high altitude flight by USAF's X-15 aircraft, shows dire need for extreme-heat resistant materials such as some inorganic polymers AUG.
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ANTHRANILIC ACID Pale yellow cryst. powder; 146°C; assay 99% min.
M.P. 145-
BENZIL Pale yellow cryst. powder; ash 0.5% max.; moisture 0.5% max.; acidity (as HC1) 0.2% max.
BENZILIC ACID off-white to ivory powder; ash 0.5% max.; moisture 0.5% max.; M.P. 148149°C; assay 99% min.
BENZOIN Pale yellow cryst. powder; ash 0.5% max.; moisture 0.5% max.; M.P. 129134°C.
GLYCEROL M0N0CHL0R0HYDRIN 3-chloro-l,2-propanediol. Light to strawcolored liquid; grades available: crude or distilled.
8-HYDR0XYQUIN0LINE White to off-white crystals; ash 0.5% max.; moisture 0.5% max.; M.P. 76°C; assay 99% min.
METHYL BENZILATE White to off-white powder; ash 0.5% max.; moisture 0.5% max.; M.P. 7 3 75°C; assay 99% min.
PARA-AMIN0BENZ0IC ACID TECHNICAL Yellowish to tan powder; ash 0.5% max.; moisture 0.5% max.; assay 98% min.
SALICYLANILIDE TECHNICAL Off-white to gray powder; ash 0.5% max.; moisture 0.5% max.; M.P. 134136°C; assay 98% min.
DR. KENDRICK R. EILAR is assistant manager of research and head of the organic chemistry section at American Potash ir Chemical's Whittier Research Laboratory. He received his doctorate in organic chemistry at the University of Colorado in 1949 and held a postdoctoral fellowship at the University of Illinois the following year, Then, after working as a research chemist with General Mills Research Laboratories, he began his association with Ampot in 1956. Dr. Eilar is an alternate councilor of the ACS Southern California Section, as well as chairman of the sections education committee and executive committeeman of the polymer group. He is a member of ACS, AAAS, Alpha Chi Sigma, Sigma Xi, and the New York Academy of Sciences.
B. L. LEMKE & CO., INC. Manufacturing
Chemists
Lodi, N. J.
at Cornell is studying —Al—N— polymers, among others, while at the University of Western Ontario, Dr. D. C. Bradley is exploring transition metal amides with an eye to polymers of the type
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Because of the known stability of certain monomeric chelate compounds, such as copper phthalocyanine (stable to about 600° C ) , and because of the potentially facile catenation of chelate systems with difunctional ligands, considerable effort has been expended to develop some useful coordination polymers on these premises. This approach has been led by Dr. John Bailar at the University of Illinois and many of his current and former students, with assistance from his polymer expert colleague, Dr. C. S. Marvel. Several chelated polymers stable to 400° to 500° C. have been obtained, but many problems still remain. As a rule, such polymers turn out to be insoluble and infusible, and in many cases they are subject to depolymerization by reorganization at high temperatures. The synthesis of double bridged coordination polymers, reported three months ago by Dr. B.
DR. R O S S I. WAGNER received his doctorate in inorganic chemistry at the University of Southern California in 1953. Since that time he has been associated with American Potash i? Chemical, where he is a group leader in the research department. Dr. Wagner is a member of ACS, Phi Lambda Upsilon, and Sigma Xi. He is the author of several papers on the chemistry of boron compounds of nitrogen, phosphorus, and sulfur.
P. Block at Pennsalt, represents a fresh approach to coordination polymers and may lead the way to realization of their potential. The one organization which has perhaps the largest stake in the development of new high temperature materials is the U.S. Air Force. It is therefore playing a major role in encouraging and supporting much of the recent research in inorganic polymers. Other government agencies have provided additional impetus to the science. As Dr. Leo Wall of the National Bureau of Standards points out, the carbon-carbon bond is and will remain difficult to beat. Throughout most of the chemistry from which inorganic polymers must derive, basic knowledge is still surprisingly sparse. But with continued efforts of the scope and intensity we see today, many new developments having both theoretical and practical importance may be expected.
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GERMAN PATENT AND TRADE MARK COUNSEL opened his office a t D a c h a u bei M i i n c h e n , A m Heideweg 2 Germany
FILLING A N D PACKAGING CONSULTANT
New transistorized circuit and ^^^ Zener diode stabilization insures top performance! Wide range, fine calibrations, and easy reading are attained with its wide scale, illuminated meter movement and dual reading scale, (.1 microns Hg. to 5000 microns Hg.). It is self-calibrating. A new transistorized circuit insures long, trouble-free use and Zener diode stabilization helps to insure accuracy to better than . 1 % . The gauge is shock resistant to 8 g.'s and is made of strong polyester, shockproof case and mount. 115 V.—50-60 cycle operation. 6" wide x Wz" high x ZVz" deep. Only $ 1 4 9 S Tube Extra $ 2 8
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ARTHUR
Manufacturing chemist with 2 0 years experience in filling, closing/ labeling and cartoning of tubes, bottles, jars, cans. Per diem basis. Chicago and Midwest area. Box 9 0 0 - F - 8 , C. &. E. N . , Easton, Pa.
CHEMICALS EXCHANGE Ion Exchange Cellulose
3E&e4£CUlcft/ DEAE - ECTEOLA - C M
I N C O N P O f t A T C O
Commercially Available Also Custom Cellulose Derivatives
F. S M I T H , I N C .
BROWN COMPANY, CHEMICAL PRODUCTS DIV. Berlin, New Hampshire
O 311 ALEXANDER ST., ROCHESTER 4 , N. Y. Write for literature on this and related items,
GUARANTEED QUALITY
>MUS\C
Other Aldehyde Bisulfite reactions products available. HEATBATH MANUFACTURING CO. . Chemical Division SPRINGFIELD 1, MASSACHUSETTS
•perfect
ORGANO
priced at far less than reproduction cost! Ideal for chemicals, gases, pneumatic use, hydraulics and liquids. HIGH PRESSURE TANKS, 500 PSI
