Raymond K. Mackie

Interaction of electron acceptors with bases—V: The Janovsky and Zimmermann reactions

Abstract When m -dinitrobenzene in excess ketone as solvent is shaken with concentrated aqueous sodium hydroxide (The Janovsky reaction), the conjugate base of the ketone appears to form a σ-addition complex with the m -dinitrobenzene; whereas the product of interaction of m -dinitrobenzene with ketone in ethanolic sodium ethoxide (the Zimmermann reaction) is the conjugate base of the corresponding 2,4 dinitrobenzyl ketone.

C-trifluoroacylation - a convenient route to carboxylic acids

Abstract Trifluoroacetic anhydride will trifluoroacylate reactive aromatic and heterocylic nuclei without the aid of a Friedel-Crafts catalyst. The resulting trifluoromethyl ketone undergoes hydrolysis to yield the corresponding carboxylic acid. This provides a very simple route to aromatic and heterocyclic carboxylic acids.

Alkene epoxidation catalysed by camphor-derived β-ketophosphonate complexes of molybdenum(VI)

New β-ketophosphonates (L) have been prepared from (R)- or (S)-camphor with various substituents on the phosphorus atom [EtO, (R)- or (S)-BusO, Ph or binaphthoxy] and reacted with [MoO2CI2] to form complexes [MoO2CI2L]. These complexes have been used to give highly active catalysts for epoxidation of alkenes by ButOOH. Very fast initial rates (ca. 400 catalyst turnovers in the first minute) gave way to much slower rates because the hemi-labile β-ketophosphonate is displaced by a diol ligand. In the presence of molecular sieves, the fast initial stage of the reaction is extended and for styrene, which gives low conversions followed by degradation in the absence of molecular sieves, styrene oxide can be formed with 98% conversion and 94% selectivity. It is demonstrated that both the ButOOH and the catalyst bind to the molecular sieves, the latter with loss of the β-ketophosphonate ligand.

Diazepines—XXII : 13C NMR spectra of 2,3-dihydro-1,4-diazepinium salts☆

Abstract The 13 C NMR spectra of a number of 2,3-dihdyro-1,4-diazepinium salts, like 1 H NMR spectra, confirm shape, and charge distribution for these compounds. The ring has a half-chair shape which is inverting rapidly at room temperature. The atoms in the conjugated portion of the ring show alternating polarity, and phenyl groups attached to these positions act, respectively, as electron-donors or electron-acceptors. A methyl substituent in the saturated portion of the ring shows equal preference for quasi-equatorial and quasi-axial conformations. Some comparisons are drawn between present results and similar results obtained with related benzene derivatives.

The interaction of electron acceptors with bases—II : The spectrum of s-trinitrobenzene in the presence of ammonia and aliphatic amines☆

Abstract The interaction of s-trinitrobenzene with certain aliphatic amines has been studied spectrophotometrically. It is suggested in solutions in ethanol or chloroform, an adduct is initially formed by a dative bond between the nitrogen of the amine molecule and the 2-position in s-trinitrobenzene. The initial reactions are reversed by acid, but in time further irreversible reactions occur.

o-Nitroaniline Derivatives - 13 reactions of N-(o-nitroaryl)sarcosine esters with bases

Abstract The title reactions give 1-hydroxy-4-methylquinoxaline-2,3-diones ( 4 ) together with a variety of mono- and bi-cyclic by-products. All of these may result from a common intermediate, viz . a 1-hydroxy-4-methyl-3,4-dihydro-1 H -2,1,4-benzoxadiazine-3-carboxylate ester ( 18 ).

Interaction of electron acceptors with bases—III : The absorption spectra of substituted polynitrobenzenes in liquid ammonia

Abstract The visible region absorption spectra of a series of substituted polynitrobenzenes in liquid ammonia has been measured. It is suggested that the absorption is produced by the respective pentadienyl anion formed by the attachment of the amide ion to the ring carbon atom of the polynitrobenzene which is ortho or para to the maximum number of nitro groups. Such structures have been proposed by Bunnett as intermediates in aromatic nucleophilic substitution reactions. Of the compounds studied primary and secondary aromatic nitro-anilines are exceptional, in that ionization appears to occur by loss of a proton from the amino group.

Interaction of electron acceptors with bases—VIII : Further considerations of the Janovsky reaction☆

Abstract Deuterium exchange is observed in methanolic solutions of m-dinitrobenzene in the presence of the methoxide ion. No visible absorption characteristic of the Janovsky reaction is observed in this system. Consequently there appears to be little support for the suggestion (based on similar exchange reactions) that the blue colour obtained with the same system in dimethylformamide or dimethylsulphoxide is necessarily due to the dinitrophenyl anion. Many compounds which have weakly acidic hydrogen atoms appear to be effective in the Janovsky reaction.

Camphor-derived β-ketophosphonate complexes of molybdenum (VI) and titanium (IV); crystal and molecular structure of dichloro [(1R)-endo-(+)-3-(diethoxyphosphoryl)camphor]dioxomolybdenum(VI)

Reaction of (1R)-endo-(+)-3-(diethoxyphosphoryl)camphor (L) with MoO2Cl2 gives [MoO2Cl2L] with cis oxygen and trans chloro ligands if the stoicheiometry is 1 : 1 whilst 2 equivalents of L give [MoO2Cl2L2]. On reaction with 1 equivalent of L, TiCl4 gives [TiCl4L]. The complexes were characterised by i.r., 1H, and 31P n.m.r. spectroscopy, and shown to contain bidentate binding (through the phosphoryl and carbonyl oxygen atoms) except for [MoO2Cl2L2], where binding is only through the phosphoryl oxygen. The compound [MoO2Cl2L] has been characterised crystallographically. Crystals are orthorhombic (space group P212121) with a= 15.528(2), b= 13.721(2), c= 9.777(1)A, and Z= 4. The structure was obtained from 1 664 observed intensities measured on a diffractometer and refined to an R value of 0.043. The complex is distorted octahedral about molybdenum with mutually cis oxygen atoms and mutually trans chlorine atoms although the O–Mo–O angle is 102.8 (5)° and the Cl–Mo–Cl angle is only 158.0(1)°. The organic ligand is bound through the phosphoryl and carbonyl oxygen atoms and the geometry of the ligand is little distorted from that of e.g. 3-bromocamphor. The bite angle for the bidentate ligand is 78.6 (3)° and the Mo–O (phosphoryl) bond length [2.183(7)A] is significantly shorter than to the cabonyl oxygen [2.402(7)A]. The known absolute configurations of the chiral centres have been confirmed as (1R), (3S), and (4S).

A high activity molybdenum containing epoxidation catalyst and its use in regioselective epoxidation of polybutadiene

MoO2CI2[3-(diethoxyphosphinyl)camphor] is a highly active catalyst for the epoxidation of alkenes by ButOOH; for polybutadiene containing cis-1,4-trans-1,4-, and 1,2-polymerised units, very high selectivity to the backbone double bonds is observed.