Syntheses of 3,7-dimethylpentadecan-2-ols from intermediates formed from co-oligomerisation reactions of butadiene with diethyl malonate and acetaldehyde

The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol.     

Proper determination of order of reactions by thermal analysis

The relationship 1– _m=1.062n ^1/1–n , well-known in non-isothermal kinetics and applied for determination of the kinetic exponentn, is not universal. A more accurate modification of the given equation is proposed in the form of a more complex function 1– _m=(n, X_m), whereX _m =E/RT _m is the dimensionless Arrhenius' criterion.     

Comportement thermique des propionates hydrates de calcium,strontium et baryum

Résumé Les propionates monohydratés de calcium, strontium et baryum ont été étudiés par radiocristallographie (sur monocristal et sur poudre) et par TG et ATD (à l'air et en milieu inerte). Ils cristallisent dans les systèmes monoclinique (Ca) ou orthorhombique (Sr, Ba). Ils perdent leur eau en une fois (Ca, Sr) ou deux fois (Ba) avec formation d'un hémihydrate intermédiaire. Tous les sels anhydres, d'abord amorphes aux rayons X, cristallisent vers 200°. Le propionate de baryum anhydre cristallisé subit une transformation polymorphique à 240°. Après 300° à l'air et 350° sous atmosphère inerte, la fusion et la décomposition se produisent simultanément: il y a dégagement de diéthylcétone et le résidu solide est du carbonate métallique bien cristallisé.

---

The monohydrates of calcium, strontium and barium propionates have been investigated by radiocrystallography (using monocrystals and the powder method) and by TG and DTA (in air and in an inert atmosphere). These compounds crystallize in the monoclinic system (Ca) or the orthorhombic system (Sr, Ba). Dehydration occurs in a single stage for calcium and strontium propionates and in two stages for barium propionate. The compound Ba(C₂H₅CO₂) 0.5 H₂O is well-defined. All the anhydrous salts, first amorphous to X-rays, crystallize at about 200°. Barium propionate undergoes another phase transition at 240°. Melting and simultaneous decomposition take place after 300° in air and after 350° in an inert atmosphere, leading to evolution of diethylketone and to a solid residue of well-crystallized metal carbonate.

---

Zusammenfassung Die Propionatmonohydrate von Calcium, Strontium und Barium wurden mittels Radiokristallographie (an Einkristallen und an Pulver), sowie mittels TG und DTA (in Luft und in inertem Medium) untersucht. Sie kristallisieren in monoklinen (Ca) oder orthorhombischen (Sr, Ba) Systemen. Sie verlieren ihr Kristallwasser auf einmal (Ca, Sr) oder zweimal (Ba) unter Bildung eines intermediären Hemihydrats. Sämtliche Anhydrosalze, welche sich zuerst bei Röntgenbestrahlung amorph verhalten, kristallisieren in der Nähe von 200°. Das kristalline wasserfreie Bariumpropionat erfährt eine polymorphe Änderung bei 240°. Nach 300° in Luft und 350° in inerter Atmosphäre treten Schmelzen und Zersetzung gleichzeitig auf: Diäthylaceton wird freigesetzt und der feste Rückstand besteht aus kristallinem Metallcarbonat.

---

, , , . - () — Sr, Ba. , — . (₂₅)₂. 0,5₂. 200°. 240° . 300° 350° , .

     

Skeletal rearrangements in mass spectra. Part I. Bis-aryl compounds

Examination of a large number of spectra indicates that bis-unsaturated compounds commonly undergo a skeletal rearrangement in which part or all or the bridging moiety is eliminated, often with concomitant loss of hydrogen atoms. The spectra of labeled azobenzene, diphenyl sulfide, and their p,p′-dimethyl derivatives show that scrambling of hydrogen atoms precedes or accompanies such rearrangements, in contrast to the loss of a p-methyl group from the latter derivatives. These results are rationalized in terms of the radical site formed on one unsaturated functional group attacking the polarizable π-electrons of the other unsaturated group.     

Effect of 2,2,6,6-tetramethyl-1-piperidinyloxy nitroxide substituent on kinetic parameters of pseudoliving polymerization

The main kinetic and thermodynamic parameters of the pseudoliving radical polymerization of styrene mediated by 4-linoleamido-2,2,6,6-tetramethyl-1-piperidinyloxy have been studied. It has been shown that the introduction of the said substituent into nitroxide leads to a marked reduction in the rate constant of reinitiation that is compensated for by the simultaneous reduction in the rate constant of reversible termination. As a result, the rate of pseudoliving polymerization, the rate of molecular mass growth, and the polydispersity of the polymer appear to be practically the same for processes mediated by both unsubstituted and substituted nitroxides.     

Synthesis of 4-Formyl-3-cyclopentene-1,1,2-tricarbonitriles

β,β,γ,γ-Tetracyanoalkanones react with acrolein at a high rate to afford the corresponding 2-substituted 4-formyl-3-cyclopentene-1,1,2-tricarbonitriles in high yields. The reaction occurs under mild conditions and is quite applicable for modification of natural and biologically active compounds possessing an R′CHC(O)CR₃ fragment to obtain their derivatives containing three cyano groups.     

Cyanoacetylene and Its Derivatives: XXXIV. Nucleophilic Addition of Tetrazole to Cyanoacetylenes

Nucleophilic addition of tetrazole to 4-hydroxy-4-alkyl-2-alkynonitriles and to 3-phenyl-2-propynonitrile occurred regiospecifically and afforded E-, Z-4-hydroxy-4-methyl-3-tetrazolyl-2-alkenonitriles and 3-tetrazolyl-3-phenyl-2-propenonitrile [20–40°C, 13–50 h, 4–15 wt% MOH (M = Na, K), THF (or DMSO)] in up to 69% yield. The attempt to perform cyclization of the hydroxy-containing adducts into iminodihydrofurans (KOH, ethanol, 23-25°C) resulted in vinyl nucleophilic substitution of the tetrazole moiety by an ethoxy group.     

Correlating second harmonic optical responses of single Ag nanoparticles with morphology

Femtosecond laser excited second harmonic (SH) activity from single Ag nanoparticles is reported. A correlation of SH single-particle measurements with high-resolution imaging of particle morphology by TEM was achieved by creating position markers on an optical and electron transparent substrate (Si3N4 thin film, approximately 100 nm). We compared the SH activity of single Ag nanoparticles (nanospheres versus nanorods) and cluster structures (composed of two or multiple particles, e.g., dimers and trimers). The direct correlation of single-particle structures and SH activity, spectral and power dependence, strongly suggests one-photon resonant driven nonlinear oscillator response mechanism.     

The influence of substituent groups on the resonance stabilization of benzene. An ab initio computational study

Accurate G3(MP2) calculations of the enthalpies of formation (Delta(f)H298) of organic molecules permit replication and extension of calculations that were formerly dependent on experimental thermochemical results. A case in point is Kistiakowski's classical calculation of the total stabilization enthalpy of benzene relative to that of cyclohexene, called for many years the "resonance energy". This paper investigates extension of the classical calculation to substituted benzenes. Slight modification of the usual procedure for Delta(f)H298 determination permits exclusion of all empirical information, leaving a purely ab initio result. Stabilization enthalpies relative to the corresponding 4-substituted cyclohexenes are presented for benzene, toluene, aniline, phenol, phenylacetylene, styrene, ethylbenzene, and phenylhydrazine. In the process of calculating these stabilization enthalpies, we have also obtained 42 values of Delta(f)H298 for monosubstituted benzenes, cyclohexenes, and cyclohexanes, 24 of which are not in the standard reference literature. For the remaining 18 G3(MP2) results, the unsigned mean difference between calculated Delta(f)H298 values and experimental results is +/-0.91 kcal x mol(-1).     

Mass spectrometry analysis of synthetically myristoylated peptides

Myristoylpeptides were synthesized in order to determine if a neutral loss of 210 Da, C14H26O (the mass of the myristoyl moiety), was universal and observable by both liquid chromatography electrospray ionization quadrupole ion trap (LC-ESI-QIT) and matrix-assisted laser desorption/ionization time-of-flight time-of-flight (MALDI-ToF/ToF) mass spectrometry. Myristoylation was successfully introduced on the N-terminus, internally on the amino group of lysine and arginine. Larger peptides and the arginine compounds needed elevated temperatures for myristoylation. To our knowledge, this is the first report of a chemically-synthesized myristoylated arginine in a peptide. Collision energy studies for the LC-ESI-QIT instrument showed that modified peptides and a loss of 210 Da could be detected under commonly used conditions (energy level between 30 and 42%) with picomole amounts of sample. The loss of myristoyl moiety is observed on the MALDI-Tof/Tof mass spectrometer as well. Due to the hydrophobic properties of the myristoyl moiety, it is not surprising that the modified peptides all formed at least dimers, and in some cases trimers. We were also able to distinguish a mixture of two mono-myristoylated peptides. MS3 data from the LC-ESI-QIT instrument on a di-myristoylated peptide indicates the loss of 210 Da at either the N-terminus or lysine. We were also able to analyze a mixture of modified and unmodified peptides on the MALDI-ToF/ToF instrument. The data presented in this paper demonstrates the constant neutral loss of the 210 Da, C14H26O, from both N-terminally and internally myristoylated peptides can be identified unambiguously using LC-ESI-QIT or MALDI-ToF/ToF mass spectrometers. This will be a useful tool in determining the myristoylation status of candidate proteins after enzyme digestion, and in elucidating the modification sites of internal myristoyl proteins.