Electron-induced ionization of undeuterated and deuterated benzoic acid isopropyl esters and nicotinic acid isopropyl esters: Some implications for the mechanism of the McLafferty rearrangement

Electron ionization mass spectra, ionization, and appearance energies and bond energies (as dissociation energies) are reported for benzoic acid-1-methyl-ethyl ester (BAIPE), benzoic acid-1-deutero-1-methyl-ethyl ester (BAIPED1), benzoic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (BAIPED6) as well as nicotinic acid-1-methyl-ethyl ester (NAIPE), nicotinic acid-1-deutero-1-methyl-ethyl ester (NAIPED1), and nicotinic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (NAIPED6). Ionization energies of 9.39 eV for BAIPE, 9.40 eV for BAIPED1, 9.26 eV for BAIPED6 as well as 9.70 eV for NAIPE, 9.79 eV for NAIPED1, and 9.65 eV for NAIPED6 were determined. A gas-phase formation enthalpy of [Formula: see text] = (−4.10 ± 0.1) eV for BAIPE is calculated as well as [Formula: see text] = (−3.35 ± 0.1) eV for NAIPE. Molecular ions show two main fragmentation pathways. The first is a classical McLafferty rearrangement, characterized by the transfer of one γ-hydrogen atom from the isopropyl ester chain leading to the ions of the corresponding acid and neutral propene. The second is the double hydrogen transfer from the ester chain leading to the formation of the protonated acid and a C3H5√ allyl radical. For BAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of ≥98%, whereas the C-1-hydrogen is transferred with a probability of ≤2%. For NAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of 90%. Experimental proton affinities of PA = (8.75 ± 0.2) eV for benzoic acid and PA = (8.43 ± 0.2) eV for nicotinic acid are derived. For the protonation of the carbonyl group, B3LYP DFT calculations yielded PA = 8.66 eV for benzoic acid and PA = 8.41 eV for nicotinic acid. The overall fragmentation mechanism is explained with the initial formation of a 1,5-distonic ion by transfer of the first hydrogen. For the transfer of the second hydrogen, an intermediate ion/neutral complex is formulated.

Cooperating dipole–dipole and van der Waals interactions driven 2D self-assembly of fluorenone derivatives: ester chain length effect

Two-dimensional supramolecular assemblies of a series of 2,7-bis(10-n-alkoxycarbonyl-decyloxy)-9-fluorenone derivatives (BAF-Cn, n = 1, 3–6) consisting of polar fluorenone moieties and ester alkoxy chains were investigated by scanning tunneling microscopy on highly oriented pyrolytic graphite surfaces.

Platinum Complexes with Edda (Ethylenediamine -N, N - Diacetate) Ligands as Potential Anticancer Agents

The design of platinum based drugs is not a new field of interest. Platinum complexes are widely used as anticancer agents and currently, approximately 30 platinum(II) and platinum(IV) entered into some of the phases of clinical trials. A special place in today’s research belongs to platinum complexes with diammine ligands. A large number of edda (ethylenediamine- N, N’-diacetate)-type ligands and their corresponding metal complexes has been successfully synthesized. This article summarizes recent progress in research on edda-type-platinum complexes. Some of these agents achieves better effect compared to the gold standard (cisplatin). It has been shown that there is a possible relationship between the length of the ligand ester group carbon chain and its cytotoxic effect. In most cases the longer the ester chain is the greater is the antitumor activity. Of particular interest are the noticeable effects of some new platinum compound with edda-type ligand on cell lines that are known to have a high level of cisplatin-resistance. Exanimate complexes appear to have a different mode of mechanism of action compared with cisplatin which includes apoptotic and necrotic cell death. There are indications that further investigations of these compounds may be very useful in overcoming the problems associated global cancer statistic.

Research of the relationship between the chain length of the dialkyl phosphate ester and the oil-based fracturing fluid viscosity

For the usage of dialkylphosphate as a gelatinizer in oil based fracturing fluid, there are two methods of preparation involved: 1.The improved ethylphosphate method is used to control one of the ester chains by using single alcohol substitute for mixed alcohols; 2.The new method of polyphosphate is used to control both of ester chains. Different kinds of alcohols are used as the raw materials in 3?3 orthogonal experiment (ratio of reactants, reaction temperature and reaction time) to obtain the optimum reaction conditions. Furthermore, 14 kinds of gelatinizers are produced by these experiments. The viscosity of the products is used as an evaluation index. The results based on these two methods show that there is a positive correlation between the length of dialkylphosphate ester chain and the viscosity of the fracturing fluid in a certain number of carbon atoms. In other words, the viscosity of fracturing fluid increased with an increasing length of the ester chain length, and reached the maximum at C13. Then the growth slowed down. The viscosity of the products which were produced by the polyphosphate method has been obviously improved by 7.72%-45.35% at the level of the other.

Vegetable Oil Derived Solvent, and Catalyst Free “Click Chemistry” Thermoplastic Polytriazoles

Azide-alkyne Huisgen “click” chemistry provides new synthetic routes for making thermoplastic polytriazole polymers—without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young’s modulus compared to C18C4 and C18C18. This was due to the “odd-even” effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries.