Showing papers on "Lewis acids and bases published in 1977"
81 citations
TL;DR: In this paper, a new route to allylic compounds of silicon and tin was proposed, which should be quite general in its scope of applicability, by appropriate variation of the phosphorus ylide and the carbonyl substrate.
Abstract: : It is obvious that this new route to allylic compounds of silicon and tin should be quite general in its scope of applicability. By appropriate variation of the phosphorus ylide and the carbonyl substrate in these reactions, allylic derivatives of silicon and tin of type Me3MCH2C(R)=CR'R'', where R, R' and R'' should be capable of wide variation, should be accessible. The allyltins thus prepared would provide starting materials for many new allylic lithium reagents. In many cases the direct lithiation procedure, the reaction of RLi/Lewis base or RLi/Me3OK with an appropriate unsaturated hydrocarbon, would provide the simplest route to the desired allylic lithium reagent. However, the additives which usually are required to effect such metalations may not always be compatible with other functionality in the carbonyl reactant or may interfere in other ways. Also, there will be instances when the appropriate unsaturated hydrocarbon is not available. Thus the versatility of our new procedure and its ease of application may prove very useful in organic and organometallic synthesis.
72 citations
Patent•
18 Mar 1977
TL;DR: In this article, the authors describe a supported catalyst-forming component which is the product obtained by contacting a titanium compound, preferably in the form of an addition product with an electron donor, with a carrier which is a mixture of an active anhydrous Mg or Mn dihalide and a solid organic material which is inert to all other components of the catalyst.
Abstract: Alpha-olefins C3 -C6 are polymerized stereospecifically with the aid of catalysts obtained by mixing (a) a catalyst-forming component which is an addition and/or substitution product of an electron-donor compound (or a Lewis base) with an aluminum trialkyl, or an addition product of an electron-donor compound with an alkyl aluminum compound containing two or more Al - atoms bound to each other through an oxygen or nitrogen atom with (b) a supported catalyst-forming component which is the product obtained by contacting a titanium compound, preferably in the form of an addition product with an electron donor, with a carrier which is a mixture of an active anhydrous Mg or Mn dihalide and a solid organic material which is inert to all other components of the catalyst including the Mg or Mn dihalide carrier.
54 citations
47 citations
TL;DR: In this article, the glass transition temperatures of binary mixtures of the lower normal alkanols with several aprotic Lewis bases have been measured as a function of composition and the initial molar slope at the pure alcohol end of the curve of Tg against mole fraction of base was accurately determined for each base.
Abstract: The glass transition temperatures (Tg) of binary mixtures of the lower normal alkanols with several aprotic Lewis bases have been measured as a function of composition. The initial molar slope (IMS) at the pure alcohol end of the curve of Tg against mole fraction of base was accurately determined for each base. A related quantity, the reduced IMS, is shown to be proportional to the excess configurational entropy per bead of base introduced into dilute solution with the base. The reduced IMS is found to be a linear function of the length of the alcohol backbone for the heavier alkanols and to be an increasing function of the base Tg. The results are interpreted in terms of alcohol and base self‐association. Some form of network association is suggested for the lighter alkanols in the supercooled liquid, while the bases most likely associate under the action of dipole–dipole or other specific nonhydrogen bonding forces. The reduced IMS values suggest association between alcohol and base, but this associatio...
47 citations
46 citations
TL;DR: In this article, the relative stabilities for the cis-and trans-snX4·2L adducts were estimated and the trends in the isomerization constant as a function of substitutions of the ligand and the halogen were discussed on the basis of tin(IV) orbital overlap.
40 citations
Patent•
17 Jan 1977TL;DR: In this paper, a battery with a nonaqueous electrolyte, an alkali metal anode and a cathode comprising a compound of grahite formed by reacting graphite with ClF 3 and a Lewis acid fluoride of an element selected from B, Si, Ge, Sn, Pb, P, As, Sb, Bi, Ti, Zr, Hf, V, Nb and Ta is described.
Abstract: A battery is disclosed having a nonaqueous electrolyte, an alkali metal anode and a cathode comprising a compound of grahite formed by reacting graphite with ClF 3 and a Lewis acid fluoride of an element selected from B, Si, Ge, Sn, Pb, P, As, Sb, Bi, Ti, Zr, Hf, V, Nb and Ta.
38 citations
TL;DR: In this paper, carbon dioxide was copolymerized with methyloxirane and 7-oxabicyclo[4.1]heptane using triethylaluminium as a catalyst component.
Abstract: Carbon dioxide was copolymerized with methyloxirane and 7-oxabicyclo[4.1.0]heptane using triethylaluminium as a catalyst component. Factors to control the copolymer composition were sought on the basis of an assumed copolymerization mechanism. Compared to nonpolar solvents, ethereal solvents were found to increase the carbon dioxide content in the copolymer obtained by the triethylaluminium/water system, giving a fraction with almost alternating sequence. The addition of a Lewis base, especially treiphenylphosphine, to triethylaluminium was also useful to get copolymers of high carbon dioxide content. The coincidence of these results with the expectation from the assumed copolymerization scheme clearly indicates that the copolymerization proceeds through a coordinated anionic mechanism.
35 citations
TL;DR: The oxide that grows on aluminum metal on exposure to room temperature air is similar in both its physical and chemical properties to γ-alumina as discussed by the authors, but it is not an aluminum hydrate.
34 citations
TL;DR: In this article, the chemisorption of ammonia and the isomerization of 1-butene on alumina have been studied in an attempt to obtain more detailed information on the nature of active sites.
TL;DR: Heats of interaction of Lewis bases with hexameric and tetrameric alkyllithiums in hydrocarbon solution at 25° have been determined by high dilution solution calorimetry at low base to lithium atom ratios.
TL;DR: Pyridinium chloride has proven useful in a number of molten salt studies where it serves as a strong chloride donor Lewis base, is freely soluble in both excess acid and excess base, and proton NMR studies have been performed on pyridine+HCl solutions in the composition range 0% −95% HCl at temperatures ranging from −100°C to 200°C as discussed by the authors.
Abstract: Pyridinium chloride, which has proven useful in a number of molten salt studies where it serves as a strong chloride donor Lewis base, is freely soluble in both excess acid and excess base. To probe the proton transfer interactions involved, proton NMR studies have been performed on pyridine+HCl solutions in the composition range 0%–95% HCl at temperatures ranging from −100°C to 200°C. This system is rich in examples of the way in which competing hydrogen bonding interactions can affect the magnetic environment of the involved protons. The most obvious of these is the increased magnetic shielding that develops in the vicinity of the N–H+ proton of the pyridinium cation as excess HCl competes for the Cl− ions, initially to form HCl2− anion and later to form more extended HCl⋅⋅⋅HCl−2 aggregates. As excess pyridine is added to PyHCl a shift in the opposite direction occurs, due either to the formation of symmetrical [Py–H–Py]+ species, to the repression of PyHCl autodissociation, or to a combination of both ...
Patent•
17 Jan 1977
TL;DR: In this paper, a novel intercalates of graphite are prepared by reacting graphite with a Lewis acid fluoride and ClF3 in the presence of HF, which are particularly useful as battery cathodes.
Abstract: Novel intercalates of graphite are prepared by reacting graphite with a Lewis acid fluoride and ClF3 in the presence of HF. These compounds are particularly useful as battery cathodes.
TL;DR: In this paper, the first order in adduct with the following activation parameters ΔH* (kcal mol −1 ) and ΔS* (cal K −1 mol − 1 ): 12.3, +21 ( cis -Me 2 CO); 15.8, +15 ( cis and trans Me 2 S); 15, +9 and 19, + 9 ( cis- and trans -TMPA).
Patent•
16 May 1977
TL;DR: In this article, the starting titanium component of Ziegler catalysts and an organoaluminum compound with a small amount of ethylene or α-olefins was modified by subjecting the copulverized titanium component to a contact with an inert organic solvent or its mixture with a modifier such as an oxygen-, sulphur-, phosphor-, nitrogen- or silicon-containing organic compound, a combination of such an organic compound and an aluminum halide, or a Lewis acid.
Abstract: Polymerization of ethylene or α-olefins using a catalyst comprising a titanium component obtained by copulverizing the starting titanium component of Ziegler catalysts and organoaluminum compound with a small amount of ethylene or α-olefins, and an organoaluminum component. The titanium catalyst component can be modified by subjecting the copulverized titanium component to a contact with an inert organic solvent or its mixture with a modifier (1) an oxygen-, sulphur-, phosphor-, nitrogen- or silicon- containing organic compound, (2) a combination of such an organic compound and an aluminum halide, (3) an organoaluminum compound or (4) a Lewis acid.
TL;DR: The photolysis of 6-[(η 5 -C 5 H 5 )Fe(CO) 2 ]B 10 H 13 in ethereal solvents leads to the formation of icosahedral metallocarboranes as discussed by the authors.
Patent•
16 Jun 1977
TL;DR: A process and a catalyst composition to effect hydrocarbon transformations comprising contacting a hydrocarbon charge with a catalyst comprising a fluorinated graphite having a fluorine to carbon atomic ratio of from about 0.1 to 1 and having bonded thereto from about 5 to 50 percent of the total weight of the catalyst of at least one Lewis acid compound selected from halides of the elements of Group IIA, IIIA, IVB, V or VIB of the Periodic Table.
Abstract: A process and a catalyst composition to effect hydrocarbon transformations comprising contacting a hydrocarbon charge with a catalyst comprising a fluorinated graphite having a fluorine to carbon atomic ratio of from about 0.1 to 1 and having bonded thereto from about 5 to 50 percent by weight of the total weight of the catalyst of at least one Lewis acid compound selected from halides of the elements of Group IIA, IIIA, IVB, V or VIB of the Periodic Table. In addition, the catalysts may also have bonded thereto a minor portion of a Bronsted acid and/or a metal of Group IVB or VIII of the Periodic Table.
Patent•
13 Dec 1977TL;DR: Polymerization of alpha monoolefins employing a catalyst comprising (a) a component formed by intensive mixing (milling) of titanium halide, a Lewis base, anhydrous magnesium or manganese chloride, and an unsaturated additive, (b) trihydrocarbylaluminum and, optionally, a leavening base, and optionally (c) a dihydro-car-byl-aluminum halide as discussed by the authors.
Abstract: Polymerization of alpha monoolefins employing a catalyst comprising (A) a component formed by intensive mixing (milling) of titanium halide, a Lewis base, anhydrous magnesium or manganese chloride, and an unsaturated additive, (B) trihydrocarbylaluminum and, optionally, a Lewis base, and optionally (C) a dihydrocarbylaluminum halide.
TL;DR: In this article, a reinvestigation of the kinetics and mechanism of ligand-exchange reactions of (2,2,7,7-tetramethyl-3,6-dithiaoctane)tetracarbonyltungsten(0), (DTO)W(CO) 4, with alkyl and aryl phosphites and phosphines (L) to afford trans-and cis-L 2 W 2 W
TL;DR: In this article, the authors reported the formation of 1 1 1 and 1 2 adducts of organotin chlorides and Bu2Sn(NCO)2 with pyridine-Noxide.
Patent•
28 Jan 1977
TL;DR: In this paper, storage-stable, liquid, only slightly colored polyisocyanates possessing carbodiimide groups and having an isocyanate content of from about 25 to 35% by weight, based on total weight.
Abstract: Storage-stable, liquid, only slightly colored polyisocyanates possessing carbodiimide groups and having an isocyanate content of from about 25 to 35% by weight, based on total weight; these products are obtained by condensing polyisocyanates in the presence of phospholines, phospholidines and/or their oxides, and stopping the condensation and stabilizing the condensation products with the Lewis acids, aromatic carboxylic acid halides, aromatic sulfonic acid esters and/or alkyl sulfates.
TL;DR: In this article, the Hildebrand and Hansen solubility parameters of the aromatic and aliphatic ester residues of poly(ethylene terephthalate), PET, are evaluated and compared to those determined experimentally.
Abstract: The Hildebrand and the Hansen solubility parameters of the aromatic and the aliphatic ester residues of poly(ethylene terephthalate), PET, are evaluated and compared to those determined experimentally. The interactions of nonaqueous solvents with the aromatic and aliphatic ester residues of PET are also described in terms of their relative basicity and acidity in the Lewis sense, where the aromatic residue may be taken as a Lewis acid and the aliphatic ester residue may be taken as a Lewis base.
Patent•
28 Apr 1977
TL;DR: In this paper, a 2-azido-D-ribofuranosyl purine compounds of the formula ##STR1## were described. But the conditions for α-and β-configuration were not specified, except that R 2 can be bound in α or β configurations.
Abstract: 2'-Substituted-D-ribofuranosyl purine compounds, especially 2'-azido-D-riuranosyl purine compounds, of the formula ##STR1## in which R 1 is azide, amino, halogen or alkoxy, and R 2 is the residue of a purine base and particularly a 9-adenyl group, a 7-guanyl group, or a 9-guanyl group (the waved lines in formula I above show that R 2 can be bound in the α- or β-configuration), Are prepared by a process comprising (a) reacting a uridine derivative with an alkali azide (when R 1 is to be azide or, through further conversion, an amine group) or a halide (when R 1 is halogen) or with an alkylating agent (when R 1 is alkoxy); (b) transforming the resulting compound with hydrazine into the corresponding 2-deoxy-ribose; (c) converting the 2-deoxy-ribose into a 1-O-methylglucoside with methanol in the presence of a strong acid; (d) reacting the glucoside with acetic anhydride in a polar organic solvent to form a 1-O-methyl-ribose-3,5-diacetate; (e) converting the diacetate with acetic anhydride in glacial acetic acid, in the presence of a strong acid into a ribose-1,3,5-triacetate; (f) condensing the triacetate obtained with a purine base with a purine base in which any free primary amino group is protected by acylation in an organic solvent in the presence of a Lewis acid to form (after splitting the protective acyl group) the desired compound wherein R 1 is azide, halogen or alkoxy; (g) optionally separating the product obtained into α and β anomers; and (h) optionally reacting the said compound obtained in step (f), in which R 1 is azido, with triphenylphosphine in saturated methanolic ammonia to yield the corresponding compound where R 1 is amino.
TL;DR: In this paper, the SH bridged complexes (CH3)3P]2(CO)3MSHM′( CO)5 existing as mer-trans and fac isomers are described.
Abstract: Die metallorganischen Lewis-Basen [(CH3)3P]2(CO)3MSH (MMn, Re) reagieren mit den Komplexen M′(CO)6 (M′Cr, Mo, W) nach dem direkten oder indirekten photochemischen Verfahren zu den SH-verbruckten Komplexen [(CH3)3P]2(CO)3MSHM′(CO)5, die als mer-trans- und fac-Isomere existieren. Die Pyrolysereaktionen der neuen Verbindungen werden beschrieben.
Organometallic Lewis Bases, XXXI. SH Bridged Dinuclear Metal Carbonyl Complexes
The organometallic Lewis bases [(CH3)3P]2(CO)3MSH (MMn, Re) react with the complexes M′(CO)6 (M′Cr, Mo, W) by the direct or indirect photochemical method to form the SH bridged complexes [(CH3)3P]2(CO)3MSHM′(CO)5 existing as mer-trans and fac isomers. The pyrolysis reactions of the new compounds are described.
TL;DR: A survey of systematic studies of the smaller boron hydrides is presented in this article, where some specific methyl substituted derivatives of these anions are described for preparing certain specifically methyl substituted derivatives of smaller borsides and borside anions.
Abstract: A survey of systematic studies of the smaller boron hydrides is presented. Relative Bronsted acidities have been determined and the Lewis base properties of anions derived by removing a bridge proton have been investigated. Addition of BH 3 to these anions results in expanded borane anion structures. These expanded structures can be converted on a large scale to B 5 H ll, B 6 H 10 , and B 6 H 12 in high yield. Principles are described for preparing certain specifically methyl substituted derivatives of the smaller boron hydrides and boron hydride anions. The nature of the basic boron-boron site in B 6 H 10 and in boron hydride anions is discussed with respect to fluxional properties and the formation of selected metalloboranes. The structures and properties of some bis-ligand adducts of B 5 H 9 and B 6 H 10 (B 5 H 9 L 2 and B 6 H 10 L 2 ) and their relationships to the hypho class of cluster systems is discussed.
TL;DR: Stannous fluoride, the widely used anticaries toothpaste additive, and other tin and germanium dihalides form complexes with hemoproteins such as hepatic cytochrome P-450, hemoglobin, and peroxidase characterized by visible spectra closely similar in shape, molar absorptivity, and absorbance maxima to those obtained with analogous complexes of carbon monoxide.
Abstract: Stannous fluoride, the widely used anticaries toothpaste additive, and other tin and germanium dihalides form complexes with hemoproteins such as hepatic cytochrome P-450, hemoglobin, and peroxidase. These complexes are characterized by visible spectra closely similar in shape, molar absorptivity, and absorbance maxima to those obtained with analogous complexes of carbon monoxide. Evidence is presented that the observed complexes are formed with uncharged MX2 or LMX2, moieties (where L is a neutral Lewis base, M is a metal, and X is a halogen) acting as pi-acceptor ligands.