Electrogeneration of triplet states of intramolecular anthracene-amine systems

In the electron transfer between the cation radicals

of the amine moiety of four intramolecular anthra cene-amine systems and the anion radicals B^XXX of some heterocyclic and carbonyl compounds in acetonitrile/toluene, the triplet state of the anthracene moiety

is formed. As intermediates in this process, intramolecular and intermolecular triplet exciplexcs

or

and

or

are discussed.     

The composition of the evolved gases from the thermal decomposition of certain metal sulfates

By the use of TG—MS, the thermal dissociation of anhydrous CuSO₄ and Al₂(S0₄)₃ was found to proceed according to the reactions:

followed by the reactions:

No SO₃ was indicated in the dissociation of alunite. The sulfate ion appears to dissociate by at least two different mechanisms although the parameter which controls the mechanisms has not been elucidated.     

Synthesis of (±)-lineatin,the unique tricyclic pheromone of Trypodendron lineatum (olivier)

(+-)-3,3,7-Trimethyl-2,9-dioxatricyclo[4.2.1.0^{4, 7}]noname

and (+-)-3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.0^{4, 7}] nonane

were synthesized. The latter was shown to be (+-)-lineatin, an ambrosia beetle pheromone.     

Electrokinetic phenomena in porous membranes: Determination of phenomenological coefficients and transport numbers

Electrokinetic phenomena in porous membranes were studied in the framework of the linear thermodynamics of irreversible processes. Phenomenological coefficients of two commercial porous membranes were determined. The variation of these coefficients with the different concentrations of NaCl used was also studied. Onsager's reciprocal relationship between cross-coefficients holds within the limits of experimental error.Membrane potentials were measured at concentrations ranging from 10^?3M to 75 X 10^?3M. The apparent transport number of the cation,

, was calculated from the diffusion potential expression. An electrometric method was used to obtain the true cation transport number,

, and the water transport number,

, for different solution concentrations, ranging from 15 x 10^?3M to 75 x 10^?3M. The true transport number of the cation,

, was also determined, taking into account water transport across the membrane. A good agreement was found between

and

values.     

Reaction of tellurium(iv) with dithizone

With an excess of dithizone over tellurium, the extraction of Te(IV) from 1 M perchloric acid solutions into a carbon tetrachloride solution (o) of dithixone follows the relation

When the acidity is varied, again with a sufficiently large excess of dithissone, the following relation seems to be approached;

(μ=1.0).     

Isomerism in poly(tetrafluoroethylene-alt-trifluoronitrosomethane)

The structures of samples of poly(tetrafluoroethylene-alt-trifluoronitrosomethane) prepared by bulk copolymerization at temperatures in the range ?30 to +90° have been investigated using ¹⁹F-NMR spectroscopy. Whilst the predominant mode of addition of CF₃NO to a growing copolymer chain gives the

radical, occasional reverse additions occur, giving

. The activation energy for the reverse addition is ca 8.5 kJ mol^?1 greater than that of the predominant propagation reaction.     

The preparation of perfluorinated esters of fluorine containing tertiary alcohols

The reaction of an aromatic lithium reagent, LiR, with a perfluoroacid anhydride (RfCO)₂O, in ether solution at low temperatures, produces esters of composition

in addition to the expected ketone

. Mixed esters of composition

may be prepared by starting with a ketone

and reacting with a lithium reagent LiR followed by perfluoroacid anhyride (RfCO₂O. Hydrolysis of the esters provide a convenient route to trertiary alcohols of composition Rf(R) ₂COH.     

A direct synthesis of 1,3-bis(bromomagnesio)propane

Careful addition of 1,3-dibromopropane

to magnesium in Et₂O yields 1,3-bis(bromomagnesio)propane

which is purified via “magnesacyclobutane”

. Reactions of

with H₂O, CO₂, HgBr₂ and Me₃SnCl are reported. MgBr₂ catalyses the decomposition of

to allylmagnesium bromide

.     

Perfluorocyclo-cycloalkenes and related oligomers

A variety of novel perfluorocycloalkene derivatives e.g. (1) – (5) may be obtained via various fluoride-ion induced reactions involving perfluorocycloalkenes. Also, pyridine-induced oligomerisation of perfluorocyclobutene gives (3), (4), and (6). Some of the chemistry of these and related compounds will be described and compared with chemistry of (7).

     

Solvolysis of bridgehead chlorides with strained bridgehead double bond.

Product study and kinetic data of the solvolysis of the bridgehead chlorides (

) and (

indicate the neighboring group participation of the strained bridgehead double bonds.     

Enthalpies de formation du nitrate d'yttrium hexahydraté et de l'ion Y3+

The dissolution enthalpies of yttrium and hexahydrated yttrium nitrate in nitric acid at different concentrations have been measured and the following enthalpies have been determined:

     

Gas phase electron diffraction study of tetraphenyltin,Sn(C6H5)4

The geometrical parameters of the tetraphenyltin molecule have been determined by gas phase electron diffraction at about 310°. The S₄ and “open” D_2d molecular models with the tetrahedral bond configuration at tin were chosen for the structure analysis. The former gave the better fit. The thermal average bond lengths (r_g, in Å) are as follows:

The benzene ring geometry appears to be almost unaffected by bonding to tin. However, tin causes an increase in the endocyclic valence angle at the ipso-carbon atom to 121.0(0.9)° rather than a decrease of that angle as might be expected, tin being a σ-electron donor. The ring plane and the plane containing the

bond and S₄ axis make an angle, ?, of 34.1(2.1)°. The

bond length in tetraphenyltin is longer than not only the

bond in tetravinyltin (r_g = 2.117(4) Å) but also the

bond in tetramethyltin (r_g = 2.144(7) A).     

Nouveau mode de cyclisation de céto-ylures.Application `a une synthèse originale d'acyl-3 hydroxy-4-coumarines et de l'hydroxy-11 benzo-(b) 12[h] xanthone-12

The thermal decomposition of keto-ylides resulting from the reaction of m - and p-acetoxy benzoyl chlorides with Ph3P=CH-COOMe leads, after saponification to m- and p-phenylpropiolic acid respectively. Ortho substitution by an acyl group generally changes the orientation of the reaction Thus o.-acetoxy-. benzoyloxy- or phenylacetoxy benzoyl chlorides respectively afford:

and

in satisfactory yields. Saponification of the first and second ones gives:

This constitutes a new, convenient route to 3-acyl 4-hydroxy cumarins and 11-hydroxy 12 H -benzo (b) xanthene 12-one. Formation of these last products involves the carbonyl oftheacyloxy-substituent and not of the acyl chloride as previously observed in these series.     

η2-acylcarbonylvanadium-verbindungen

Substituted vanadium carbonyl compounds with η²-bonded acyl ligands (η²-RCO)V(CO)₃

(

= ditertiary phosphines or arsines: dppe, dppp, dppm, diars, arphos, dpase) have been prepared by photochemical reaction of [V(CO)₄

] with various substituted benzoyl chlorides and cyclopropanylcarbonyl chloride.Effects of aromatic substituents and

upon the thermal stability of the η²-acylcarbonylvanadium compounds are discussed. IR ν(CO) force constants and ⁵¹V NMR signals are linearly correlated with Hammett's σ constants of the aromatic substituents.The preparation of V(CO)₂Cl(diars)₂ is described.     

The dynamics of reactions of O(3P) atoms with allene and methylacetylene

The reactions of O(³P) atoms with allene and methylacetylene: O+CH₂=C=CH₂

CO+C₂H₄,ΔH₁⁰ = ?119.4 kcal/mole, O+CH₃-C

CH

CO+C₂H₄,ΔH₂⁰ = ?117.8 kcal/mole were studied at 293 K with a CO laser resonant absorption and a discharge-flow GC-sampling method. The CO formed in reaction (1) was found to have a vibrational temperature of 5100 ± 100 K, compared with 2400 ± 200 K in (2). The good agreement between the observed CO vibrational distributions and those predicted by simple statistical models indicates that the reaction energies were completely randomized.The present results also showed unambiguously that CH₃CH, instead of C₂H₄, was produced initially in reaction (2).     

Evidence for the direct isomerization of a platinocyclobutane to an olefin complex

Dichloro-2,3,3-trimethyl-1-platinocyclobutane,

, prepared by the metathetical reaction of Zeise's dimer and 1,1,2-trimethylcyclopropane, reacts with pyridine in chloroform to produce a platinum complex of 2,3-dimethyl-1-butene

. Reaction of I with pyridine at low temperatures (ca. ?40° C) leads to a pyridine addition compound (III) in which the platinocyclobutane ring remains intact. The thermal isomerization of III, which may be conveniently studied using NMR, produces a mixture of II and the free olefin.     

Laser flash photolysis of iodine-iodide mixture in hydroxylic solvent. Evidence for the existence of the radical anion I

The laser flash photolysis of iodine-iodide mixtures in alcoholic solvents produces transient species absorbing in the red and near infrared region with maxima at 740 and 590 nm. The 740 nm absorption band has already been attributed to the well known I

ion. In this work the 590 nm absorption band is assigned to the I

radical anion which presumably could be formed by the equilibrium reaction: I

+ I₃^- ? I

. The variations of the intensities of the 590 and 740 nm transient absorption bands as a function of I₃^? concentration, temperature and solvent, support this assignment. The kinetics of formation of I

and I

has been studied in solutions of tertiary butanol. An analysis of the experimental results shows that the I

ion could be formed via a mechanism involving an I

intermediate.     

Thermal decomposition of cyclic alkylidine peroxides (tetraoxanes)

Thermal decomposition of molten 6,6-bis-(4-methoxycarbonyl-butyl)-1,2,4,5-tetraoxane has kinetic parameters similar to those of the other dialkyl peroxides:

A similar behaviour has also been found for 6,6-bis-(4-aminocarbonyl-butyl)-1,2,4,5-tetraoxane dissolved in dimethylformamide:

In the absence of solvent this cyclic dimeric peroxide is uncommonly stable owing to the relatively high melting point. The increase in activation energy and frequency factor (compensation effect) at the decomposition in the absence of solvent is explained by the stabile aggregation of the amino derivative of tetraoxane in the crystalline state.The reaction heat of the exothermic decomposition reaction equals 102 for the methoxy and 96±6 kcal mol^?1 for the amino derivative.The measurements of rate constants and reaction heat were carried out by the method of differential enthalpic analysis.