Kurt Moedritzer

Synthesis and properties of mono- and poly-methylene-diphosphonic acids and esters

Abstract A series of methylenediphosphonic acids, (HO)2OP(CH2)nPO(OH)2, (n = 1, 2, 3, 4, 5, 6 and 10) have been prepared by hydrolysis of the corresponding tetra-ethyl esters. The esters with n ⩾ 3 were obtained by either a Michaelis-Becker or an Arbuzov-Michaelis type reaction. For n = 1 or 2, a modified Michaelis-Becker reaction was utilized. The 31P nuclear magnetic resonance chemical shifts as well as the infra-red spectra show that as n increases the effect of the two end phosphorus atoms on one another decreases, and becomes very small for n > 3. The X-ray diffraction patterns of the diphosphonic acids are reported.

The structure of dialykl and diaryl phosphonates

Abstract Nuclear magnetic resonance (n.m.r) studies of the 31 P nucleus in alkali metal salts of dialkyl and diaryl phosphonates dissolved in diglyme demonstrate that the phosphorus in such salts exists in the trivalent form. Acid base studies show that the salts of dialkyl phosphonates resemble to alcoholates with respect to their base strength.

Redistribution Equilibria of Organometallic Compounds

Publisher Summary This chapter reviews work on redistribution equilibria and describes the principles underlying the mathematical treatment of such equilibria as well as the general implications of these equilibria with respect to general chemistry. The overall process merely is a rearrangement of covalent bonds, with the total number of σ-bonds of any type remaining constant. However, other effects may also be quite significant-effects such as hybridization changes or nonbonding interactions, including steric factors and dipole interactions. When monofunctional and difunctional substituents are sorted on a polyfunctional moiety, a large number of molecular structures are possible ranging from the simple structures in which all of the sites of the polyfunctional moiety are filled by mono-functional substituents through molecules of increasing complexity to the most complicated structures in which the poly-functional moieties are held together by difunctional or bridging substituents. Equilibrium constants for the exchange of the constituent atoms between building units truly apply only to the ring-free portion of the molecules and the presence of simple cyclic molecules can be shown to cause a continuous increase in the apparent value of such equilibrium constants as the amount of bridging units is increased with respect to the mono-functional substituents.

Molecular Distributions at Equilibrium. III. Ring—Chain Equilibrium in the Dimethylsilthians

By heating mixtures of cyclic dimethylsilthians with either dichlorodimethylsilane, dimethoxydimethylsilane, or dimethylmercaptodimethylsilane, liquids are formed which are shown to be mixtures of molecules by proton nuclear magnetic resonance. The equilibria resulting from exchange on the dimethylsilicon moiety of bridging sulfur atoms with either chlorine atoms, methoxyl, or methylmercapto groups is shifted strongly towards the ring compounds. At equilibrium, two sizes of rings are seen, with the trimer predominating over the dimer. The appropriate equilibrium constants giving the distribution of chains and of rings and relating the chain distribution to the ring distribution are presented.

Exchange of substituents between the dimethylsilicon and the dimethylgermanium moieties

Abstract Equilibria in the scrambling between dimethylsilicon and dimethylgermanium of chlorine, bromine, or iodine with either methoxyl or methylthio groups have been studied by proton nuclear magnetic resonance. The scrambling of methoxyl with the methylthio group is also reported. As expected, most of these equilibria deviate greatly from the values corresponding to random sorting of the substituents. The mathematical treatment of the scrambling of two kinds of substituents between two different central moieties (including atoms) is discussed and typical examples are presented for the variation with over-all composition of the six molecular species resulting from such scrambling on a pair of bifunctional moieties.

Proton NMR study of the equilibria between cyclic disilthianes and trisilthianes

Abstract The equilibria in solution between the tetra-atomic ring structure of tetramethylcyclodisilthiane and the hexa-atomic ring structure of hexamethylcyclotrisilthiane were studied by proton nuclear magnetic resonance spectroscopy. Equilibrium constants determined at various temperatures and dilutions show that in accordance with the principle of Le Chatelier high (low) temperatures and high (low) dilutions favor the formation of thesmaller (larger) sized ring structure. The ring strain energy in the cyclic dimer is about 3 kcal per monomer unit.

NMR study of the equilibrium between trimeric and tetrameric ring structures of dimethylgermanium oxide

The equilibria in solution between trimeric and tetrameric forms of dimethylgermanium oxide have been studied by proton NMR. From the data obtained in this study equilibrium constants for the reaction: 4[(CH3)2GeO]3 ⇄ 3[(CH3)2GeO]4 were determined; Koo4,3  5.98 at 35°, and 0.52 at 103°. The rate of equilibration has been studied in dilute solution and catalytic effects by dimethyldihalogermanes are interpreted in terms of oxygen-halogen exchange reactions.

Scrambling of pseudohalogen groups on the dimethylsilicon moiety

Abstract Proton nuclear magnetic resonance was employed in a quantitative study of most of the equilibria resulting from scrambling on dimethylsilicon of isocyano, isocyanato, and isothiocyanato groups with each other and with the chloro, bromo methoxy, and methylthio groups. The pseudohalogen groups behave similarly to the halogens with respect to deviations from additivity in Pauling-type bond energies.

1-Chloro and 1-Hydroxyphospholene-1-oxides

Abstract A one-step, high-yield procedure is reported for the preparation of a 1:1 mixture of the two isomers of 1-chlorophospholene-1-oxide which may be separated by spinning band distillation. The isomerically pure chlorides were hydrolyzed to form the corresponding 1-hydroxyphospholene-1-oxides. These, as well as the precursor chlorides, were characterized by 1H and 31P nmr, mass spectrometry and IR.

A Novel Synthesis of Aminomethylphosphonic Acid

Abstract Aminomethylphosphonic acid, H2NCH2P(O) (OH)2, was prepared in high yield from t-butylaminomethylphosphonic acid, t-C4H9NHCH2P(O) (OH)2, by iso-buty-lene elimination in concentrated aqueous hydrobromic or hydrochloric acid at 175° in a sealed tube. The corresponding ester, t-C4H9NHCH2P(O) (OC2H5)2, the precursor of the acid, which is easily obtained from N-methylene-t-butyl-amine and diethyl phosphonate, may also serve as starting material for this preparation.