P-tolyl Groups Research Articles

Cobalt-catalyzed cyclo-cotrimerization of alkynes and heterocumulenes

The cyclo-cotrimerization of alkynes and heterocumulenes (carbodiimides, isocyanates and carbon dioxide) in the presence of [Co(η 5-C 5H 5)-(C 2H 4) 2], (I), has been studied. This complex exhibits excellent catalytic properties in the cocyclization of alkynes with diimides and isocyanates. Variable amounts of benzene derivatives are also formed in all cases. The yields of both benzene compounds and co-trimers are particularly good in the case of terminal alkynes. (I) is also active in the cocyclization of 1-hexyne with CO 2 to give 4,6-dibutyl-2-pyrone in poor yields. The regioselectivity of the reactions involving RNCNR or RNCO is markedly dependent on the nature of the R group. Two isomeric cotrimers, i.e. the 4,6- and the 3,6-disubstituted derivatives, are formed when R is the cyclohexyl group. When R is the phenyl or the p-tolyl group, only one isomer is formed: the 4,6-disubstituted derivative in the case of carbodiimides, and the 3,6-disubstituted derivative in the case of isocyanates.

Crystalline structure of poly(diaryl siloxanes)

Transmission electron microscopy and X-ray diffraction were used to resolve the crystalline structure of linear poly(diphenyl siloxane) and also two polymers that contain p-tolyl substituents at the silicon atom along with phenyl substituents. It has been shown that an increase in the number of p-tolyl groups per macromolecule leads to an increase in the cross-sectional area of the unit cell per chain. The softening temperature is thereby lowered, and polymer solubility improved.

SPECIFIC RECOGNITION OF NONPOLAR GROUPS IN AQUEOUS MEDIA. LARGER SELECTIVITY DIFFERENCES IN OXIDATION OF ASSOCIATING THIOLS IN AQUEOUS MIXED SOLVENTS THAN IN NONAQUEOUS ONES

Abstract Environment dependence of the selectivity in oxidation of a pair of associating thiols was examined in binary solvent mixtures of an alcohol or acetonitrile with water and an organic cosolvent. The discrimination between the two nonpolar groups (n- and i-C5H11 groups, phenyl and p-tolyl groups, or n- and i-C4H9 groups) of one of the thiols was found to occur more specifically in aqueous media than in the corresponding nonaqueous media.

Synthesis of 2-substituted 2,6-dihydro-3-hydroxy-7H-pyrazolo(4,3-d)pyrimidin-7-ones.

2-Substituted 2, 6-dihydro-3-hydroxy-7H-pyrazolo [4, 3-d] pyrimidin-7-ones bearing a methyl, phenyl, p-tolyl, m-tolyl or p-chlorophenyl group at the 2-position were synthesized by the reduction of ethyl 4-nitroso-5-hydroxy-1H-pyrazole-3-carboxylates and subsequent condensation of the resulting ethyl 4-amino-5-hydroxy-1H-pyrazole-3-carboxylates with formamide. Ethyl 4-nitroso-5-hydroxy-1H-pyrazole-3-carboxylates were prepared by nitrosation of ethyl 5-hydroxy-1H-pyrazole-3-carboxylates, which were derived from diethyl oxalacetate and monosubstituted hydrazines such as methyl-, phenyl-, p-tolyl-, m-tolyl-, and p-chlorophenylhydrazines.

Studies on (SCN)2M(NCS)2Hg2(p-tolyl)2 and (SCN)2M(NCS)2Hg2(α-naphthyl)2 and their complexes

p-Tolyl mercury thiocyanate and α-naphthyl mercury thiocyanate react with Co(NCS)22py and form a bimetallic pink compound of formula (py)2(SCN)2Co(NCS)2Hg2R2 (R = p-tolyl and α-naphthyl group). On heating this compound in vacuum a blue compound (SCN)2Co(NCS)2Hg2R2 is formed. Nickel analogues (SCN)2Ni(NCS)2Hg2R2 are formed by direct reaction of p-tolyl or α-naphthyl mercury thiocyanate with nickel thiocyanate. (SCN)2Co(NCS)2Hg2R2 and (SCN)2Ni(NCS)2Hg2R2 act as Lewis acids and form complexes with bases. The Lewis acids and their complexes with various bases have been characterized by elemental analyses, molar conductance, molecular weight, magnetic moment, infrared and electronic spectral studies. These studies reveal that both the Lewis acids are monomers. In (SCN)2Co(NCS)2Hg2R2 the CO(II) has tetrahedral geometry, where as in (SCN)2Ni(NCS)2Hg2R2 the Ni(II) has octahedral geometry through elongated axial bondings with SCN-groups of other molecules. Thiocyanate bridging of the type R-Hg-SCN-M [M = Co(II), Ni(II)] is present in the compounds. Pyridine and dimethylsulphoxide form adducts with these compounds by coordinating at Co(II) or Ni(II). The thiocyanate bridge is retained in these complexes. 2-2′bipyridyl ruptures the thiocyanate bridging in both the Lewis acids and forms cationic-anionic complexes of the type [M(L-L)3][RHg(SCN)2]2. In both the type of complexes Co(II) and Ni(II) possess octahedral environment. The “softness” values have been used in a novel manner in proposing the structure of the complexes.

ChemInform Abstract: THE CHEMISTRY OF SMALL‐RING COMPOUNDS. PART 39. DISPLACEMENTS IN CYCLOPROPYL CHLORIDES ACTIVATED BY ELECTRON‐DONATING SUBSTITUENTS

AbstractDas Chlorid (Ia) geht bei ‐30 °Cmit Methanol über das Ion (IIa) in den Diether (IIIa) über.

Degenerate and nondegenerate rearrangements of the 7-borabicyclo[..1]heptadiene system: Twofold [1,3] supra-facial sigmatropic migrations and anionic [1,] carbon-boron shifts

Two notable skeletal rearrangements of the 7-borabicyclo[..1]heptadiene system (III) have been uncovered: (1) a facile, degenerate, net twofold [1,] suprafacial sigmatropic migration of the 7-substituted boro group, observable by NMR spectroscopy when the carbon centers of the borole (I) and alkyne (II) bear suitable groups; and () a nondegenerate, anionic [1,] aryl shift from carbon to boron, converting the 7,7-dimethylborate salt of III into an aryl(dimethyl)pentaarylborate salt. Thus, the degenerate rearrangement was revealed when pentaphenylborole (Ia) was allowed to react with di- p-tolylacetylene (IIb) at 5°C; the resulting 7-borabicyclo[..1] heptadiene (III) formed displayed NMR methyl signals characteristic of p-tolyl groups located at both C 5 and C 6, as well as C 4 and C 5. Similarly, the nondegenerate, disruptive anionic isomerization of the 7,7-dimethylborate salt of IIIe or IVe was found to involve migration of either phenyl or p-tolyl groups from carbon to boron, showing that both phenyl (IIIe) and p-tolyl groups (IVe) were located at the bridgeheads in the precursors to VI.

Synthesis and Decomposition of Alkane- and Arenesulfonyl Aryl Disulfides

Abstract Pyridinium alkane- and arenethiolsulfonates were allowed to react with arenesulfenyl chlorides, CISAr′, to yield sulfonyl disulfides in which R is n-dodecyl, benzyl, phenyl, or p-tolyl group, and Ar′ o-nitrophenyl or o-nitro-p-chlorophenyl. p-Toluenesulfonyl p-nitrophenyl disulfide was also prepared by this method. IR and UV spectra of these compounds were determined and compared with those of the corresponding thiolsulfonates. Decomposition of 35S-labeled p-toluenesulfonyl p-nitrophenyl disulfide, p-CH3C6H4SO2S35SC6H4NO2-p, gave 35S-labeled p-nitrophenyl p-toluenethiolsulfonate, p-CH3C6H4SO235SC6H4NO2-p. Triphenylphosphine was found to attack two oxygen atoms and a sulfur atom of p-toluenesulfonyl o-nitrophenyl disulfide at the same rate. The reaction of triphenylphosphine with 35S-labeled p-toluenesulfonyl o- and p-nitrophenyl disulfides revealed that the central sulfur atom of these sulfonyl disulfides was desulfurated. This result coincides with that of the decomposition mentioned above. The susceptibility of sulfonyl disulfides containing p-nitrophenyl group to the decomposition and the desulfuration of the central sulfur atom of sulfonyl disulfides in general are also discussed.

Organosilicon chemistry I. Octaarylspiro[5.5]pentasiloxanes

A series of six octaarylspiro[5.5]pentasiloxanes containing phenyl, m-tolyl, and p-tolyl groups have been synthesized by treating a disiloxanediol with either SiCl4 (for simple bicyclic) or with a dichlorocyclotrisiloxane (for mixed bicyclic). They can be rearranged into non-crosslinking polymers. The structures of these polymers have been proposed based on PMR studies and steric considerations.

The crystal and molecular structure of dichlorotris(tetrahydrofuran)-p-tolylchromium(III)

The structure of dichlorotris(tetrahydrofuran)-p-tolylchromium(III), pCH3C6H4CrCl2,3THF, has been determined by single crystal X-ray diffraction methods. The crystals are orthorhomic, space group Pbca with a= 10·396, b= 18·447 and c= 22·396 A. The chromium is octahedrally co-ordinated with two chlorine ligands trans and two tetrahydrofuran ligands trans: the p-tolyl group, which is sigma-bonded to the chromium (Cr–C = 2·014 ± 0·010 A), is trans to the third tetrahydrofuran ligand. The Cr–O bonds which are trans to one another are essentially equal and are normal in length (2·045 ± 0·008 A). However, the Cr–O bond to the tetrahydrofuran group trans to the p-tolyl group is much longer (2·214 ± 0·007 A) than the other two.

STEREOCHEMISTRY OF ARSENIC: PART VI. TRI-p-TOLYLARSINE

Crystals of tri-p-tolylarsine are rhombohedral, with cell dimensions a = 9.84 Å, α = 80° 2′, and space group [Formula: see text]. There are two molecules in the unit cell, and hence the molecule has symmetry C3. The structure has been determined from a projection along the rhombohedral cell axis, and the bond lengths and valency angles are given. In comparison with an ideal model having maximum interaction between the arsenic lone pair and the aromatic π-electrons, each ring is rotated about its As—C bond by 36°, the three rotations being in the same sense. These displacements increase overcrowded distances in the ideal model to about the normal van der Waals separations, the closest intramolecular contacts between p-tolyl groups being [Formula: see text] and [Formula: see text]. All the intermolecular contacts correspond to van der Waals interactions.

Studies on the some heterocyclic pyrimidine derivatives of nitrogen. II. Syntheses of pyrimidines

Five kinds of pyrimidine derivatives (VII) substituted in 2-position with phenyl, o-tolyl, p-tolyl, p-nitrophenyl, and p-bromophenyl groups were prepared, following the synthesis of 2-amino-4-methyl-5-ethoxycarbonylpyrimidine (I). 2-Ethoxymethyleneacetoacetate (III) was prepared from ethyl acetoacetate. Five kinds each of nitriles (IV), imidoethers (V), and amidine base hydrochlorides (VI) were prepared from aromatic primary amines such as aniline, o-toluidine, p-toluidine, p-nitroaniline, and p-bromoaniline. Condensation of the amidines (VI) with the ester (III), in the presence of sodium ethoxide as the condensation agent, resulted in smooth reaction to afford the corresponding esters (VII: R=C2H5). Hydrolysis of these esters (VII) by the usual method gave the corresponding free salts (VII: R=H). In the series of this work, condensation of acetamidine hydrochloride and the ester (III) failed to afford the pyrimidine derivative.

クロラムフェニコール関連化合物の研究 (第7報)

The reaction of thionyl chloride with dl-erythro- and dl-threo-1-phenyl-1-p-tolyl-2-benzamido-1, 3-propanediol, the compound formed by substitution of hydrogen in 1-position of 1-phenyl-2-amino-1, 3-propanediol with p-tolyl group, results in formation of oxazoline accompanied with steric inversion. Hydrolysis followed by basification afforded N-benzoylated isomers with steric configuration different from that of the starting material. This has proved that mutual conversion between threo and erythro types is possible.

On the Catalytic Action of Japanese Acid Earth. XI. The Isomerisation of Aldehydes to Ketones and the Explanation of the Migration of the Radicals from the Standpoint of the Electronic Theory (Continued and concluded)

Abstract (1) All the phenomena hitherto ascribed to the characteristic catalytic action of Japanese acid earth can be explained by taking its strong electron-seeking property into consideration. Thus its ability to promote the hydrolysis of cane sugar or starch and the oxidation of pyrogallol and its property to give various oxidase-like colour reactions are all due to its selective adsorptive power for hydroxyl ion. The facts can similarly be explained that the dehydration or deamination of various organic compounds takes place through its catalytic action followed by the intramolecular rearrangement, as observed in the reaction of producing cyclopentane derivatives from cyclohexanol, cyclohexylamine or their methyl derivatives. The initial step of the formation of β,β′-dinaphthyl from naphthalene in the presence of the earth is the polarisation of the naphthalene molecule promoted by its electron-seeking property. (2) Several diarylacetaldehydes have been newly synthesised and found to rearrange themselves to give the corresponding ketones, when heated at 300°C. in the presence of the earth. Thus phenyl p-tolyl and m-tolyl p-tolyl acetaldehydes gave phenyl p-methylbenzyl and m-tolyl p-methylbenzyl ketones respectively, while o-tolyl p-tolyl and p-tolyl p-chlorophenyl acetaldehydes gave the respective mixtures of o-toly p-methylbenzyl and p-tolyl o-methylbenzyl ketones and of p-chlorophenyl p-methylbenzyl and p-tolyl p-chlorobenzyl ketones. (3) By comparing the yields in the isomeric ketones thus produced the order of the facility of separation of the different aryl groups was determined as follows:— Phenyl, m-tolyl>p-chlorophenyl>o-tolyl>p-tolyl. The phenyl group may most probably have the greater migratory tendency than the m-tolyl. (4) The mechanism of the conversion of the aldehydes to the ketones has been discussed. It has been postulated that an electromeric displacement of electrons in the carbonyl group (Remark: Graphics omitted.) is promoted by the action of the earth, and one of the aryl groups migrates with its valency electrons from the adjacent a-carbon atom to the depleted carbonyl carbon. A proton is then splitted from the carbonyl carbon and unites with the carbonyl oxygen to give the enolic form of the ketone, isomeric to the aldehyde. The conclusion has been reached that the more electron-attracting of the two aryl groups must be first separated as anion. (5) It was confirmed that the capacity of the p-tolyl group for electron-release is much larger than those of o-tolyl, m-tolyl, phenyl and p-chlorophenyl groups. By these results a new chemical evidence has been given for the tautomeric effect of the methyl group. (6) Following compounds have been newly synthesised and their constitutions were confirmed:— a-phenyl a-p-tolyl, a-m-tolyl a-p-tolyl, a-o-tolyl a-p-tolyl and a-p-chlorophenyl a-p-tolyl ethylene glycols and their benzoyl derivatives; p-tolyl m-methylbenzyl, m-tolyl p-methylbenzyl, o-tolyl p-methylbenzyl, p-tolyl o-methylbenzyl, p-chlorophenyl p-methyl-benzyl and p-tolyl p-chlorobenzyl ketones and their oximes and semi-carbazones; m-tolyl p-tolyl, o-tolyl p-tolyl and p-tolyl p-chlorophenyl acetic acids; p-methylbenzoyl carbinol, p-chlorobenzoyl methyl acetate and p-chlorobenzoyl carbinol. (7) o-Tolyl p-methylbenzyl and m-tolyl p-methylbenzyl ketones have been found to be oxidised slowly by the action of atmospheric oxygen on long standing, giving the mixtures of o-toluic and p