Benzyl Methyl Research Articles

Simultaneous Determination of Multiple Preservatives and Antioxidants in Topical Products by Ultra-Pressure Liquid Chromatography with Photo Diode Array Detector

An improved analytical method was developed by ultra-pressure liquid chromatography (UPLC) using design of experiments (DoE) for quantification of preservatives and antioxidants. Benzyl alcohol, benzoic acid, phenoxy ethanol, sorbic acid, methyl paraben, ethyl paraben, propyl paraben, and butyl paraben were selected as preservatives for the study. Similarly, propyl gallate, butylated hydroxy anisole, butylated hydroxy toluene, and ascorbyl palmitate were selected as antioxidants. Cream, gel, ointment, and lotion formulations containing these components were manufactured and quantified using this method. Separation was performed by liquid chromatography (LC) using reverse phase silica base C18 (2.1 mm × 100 mm, 1.7 µ) column equipped with photo diode array detector. 0.1% v/v ortho-phosphoric acid in water, methanol, and acetonitrile were used for gradient elution. Moreover, extraction and solution stability study of highly oxidizable compound ascorbyl palmitate was performed using a peculiar combination of diluents. The method was found to be simple, precise, accurate, and stability indicating. The applicability of the method was also suggested by evaluating the marketed topical formulations.

Biodegradation of benzalkonium chlorides singly and in mixtures by a Pseudomonas sp. isolated from returned activated sludge

Bactericidal cationic surfactants such as quaternary ammonium compounds (QACs) are widely detected in the environment, and found at mgkg−1 concentrations in biosolids. Although individual QACs are amenable to biodegradation, it is possible that persistence is increased for mixtures of QACs with varying structure. The present study evaluated the biodegradation of benzyl dimethyl dodecyl ammonium chloride (BDDA) singly and in the presence of benzyl dimethyl tetradecyl ammonium chloride (BDTA) using Pseudomonas sp., isolated from returned activated sludge. Growth was evaluated, as was biodegradation using 14C and HPLC-MS methods. BDTA was more toxic to growth of Pseudomonas sp. compared to BDDA, and BDTA inhibited BDDA biodegradation. The benzyl ring of [U-14C-benzyl] BDDA was readily and completely mineralized. The detection of the transformation products benzyl methyl amine and dodecyl dimethyl amine in spent culture liquid was consistent with literature. Overall, this study demonstrates the antagonistic effect of interactions on biodegradation of two widely used QACs suggesting further investigation on the degradation of mixture of QACs in wastewater effluents and biosolids.

Purification and Molecular Characterization of an [FeFe]-Hydrogenase from <i>Thermotoga hypogea</i>

Thermotoga hypogea is a hyperthermophilic bacterium growing on carbohydrates and peptides, producing acetate, CO2 and H2 as major end products. Hydrogenase activity was detected in the cell-free extract of T. hypogea and a hydrogenase was purified to homogeneity. The purified enzyme was homotetrameric with a subunit of 65 kDa, and contained 16 atoms of Fe and 11.6 atoms of acid labile sulfur per mole subunit. The gene encoding the hydrogenase was sequenced, and four iron-sulfur clusters including the H-cluster were found to be present in the gene sequence, indicating it is an [FeFe]-hydrogenase. The enzyme was oxygen sensitive with a t1/2 of 3 min when exposed to air. It was thermostable with t1/2 values of approximately 40 and 15 min when incubated at 70°C and 85°C, respectively. The optimal temperature for the hydrogenase activity was about 85 °C. Both benzyl viologen (BV) and methyl viologen (MV) could serve as electron acceptors, and the apparent Vmax values were determined to be 1,142 and 607 μmol H2 oxidized min-1 mg-1, respectively. For H2 uptake activity, the apparent Km values for MV and BV were 0.17 and 0.24 mM, respectively. For H2 evolution activity, the apparent Km value for MV and apparent Vmax value were determined to be 1.1 mM and 192 μmol min-1 mg-1, respectively. Ferredoxin purified from T. hypogea served as electron carrier. The enzyme exhibited pH optima of 10.0 and 8.0 for the H2 uptake and evolution activities, respectively. The physiological function of the enzyme is proposed to catalyze the H2 evolution. Keywords: [FeFe]-hydrogenase, ferredoxin, iron-sulfur clusters, ferredoxin, hydrogen production, hyperthermophiles, Thermotoga hypogea.

Enhanced morphology and mechanical characteristics of clay/styrene butadiene rubber nanocomposites

Achieving complete exfoliation of clay in their polymer nanocomposite is a matter of interest as it can significantly affect the material properties. Herein, an efficient way of enhancing the interlayer spaces of organically modified clays (OC) containing two types of surfactants, benzyl methyl hydrogenated tallow (Cloisite 10A) and dimethyl dihydrogenated tallow (Cloisite 20A) while mixing with the styrene butadiene rubber (SBR) is reported. The prolonged swelling of the OC in toluene helped the rubber chains to disentangle in the interlayer spaces identifiable from the morphology and the change of the d-value. The small angle X-ray scattering traces for all the Cloisite 20A/SBR composites indicated a very extensive dispersion of the OC and using the Guinier equation from SAXS, radius of gyration was calculated. An optimal size of 6–7nm for the dispersed clay particles was found for maximizing resistance to abrasion as well as mechanical properties. Finally the enhanced tensile properties were correlated with the vulcanization behavior as well as the filler/polymer interfacial interaction from rheology through the completely exfoliated morphology observed for the swollen clay filled samples. Moreover an exclusive mechanism for curing of the composites was also derived.

Side-chain-type poly(arylene ether sulfone)s containing multiple quaternary ammonium groups as anion exchange membranes

A new difluorodiphenyl sulfone monomer, 3,3′,5,5′-tetra(3′′,5′′- dimethylphenyl)-4,4′-difluorodiphenyl sulfone (M-DFDPS), was synthesized and further polymerized to form a series of poly(arylene ether sulfone)s containing four pendent 3,5-dimethylphenyl groups. After bromination of benzylmethyl groups, side-chain-type poly(arylene ether sulfone)s containing multiple quaternary ammonium groups in pendant phenyl rings (PAES-Q-xx) were prepared by quaternization. Their chemical structures and some properties, including water uptake, swelling ratio, hydroxide conductivities, and thermal and alkaline stabilities, were investigated. These PAES-Q-xx membranes with IEC values of 1.65–2.36 mequiv/g had low water uptake and swelling ratio. Their conductivities were all above 10mS/cm and the values were in the range of 23–37 and 54–82mS/cm at 20 and 80°C, respectively. The good conductivity is probably due to the high IEC and the dense distribution of the pendant quaternary ammonium groups. In addition, PAES-Q-xx membranes also displayed good thermal and alkaline stabilities.

Enantioselective Synthesis of β-Arylamines via Chiral Phosphoric Acid-Catalyzed Asymmetric Reductive Amination.

A new method for the synthesis of chiral β-aryl amines via chiral phosphoric acid-catalyzed enantioselective reductive amination of benzyl methyl ketone derivatives with Hantzsch ester was developed. Various chiral β-aryl amines were obtained in high yields and with good to high enantioselectivities. This transformation is applicable to gram-scale reactions, and the catalyst loading can be reduced to 1 mol % without sacrificing any catalytic efficacy. Furthermore, the resulting β-aryl amine was successfully converted into a tetrahydroisoquinoline compound without any loss of enantioselectivity.

Volatile organic compounds released by Rumex confertus following Hypera rumicis herbivory and weevil responses to volatiles

AbstractWe report in this study large induction of volatile organic compounds (VOCs) from a single inflorescence of mossy sorrel (Rumex confertus Willd., Polygonaceae), by herbivory of the weevil (Hypera rumicis L., Coleoptera: Curculionidae). VOCs blend induced by the weevil herbivory included 1 green leaf volatiles (GLVs) ((Z)‐3‐hexen‐1‐yl acetate), five terpenes ((Z)‐β‐ocimene, linalool, geranyl acetate, β‐caryophyllene and (E)‐β‐farnesene), three esters (benzyl acetate, methyl salicylate and methyl anthranilate) and one aromatic heterocyclic organic compound (indole). Uninjured plants produced only detectable amounts of VOCs. A Y‐tube experiment revealed that both females and males of H. rumicis were not attracted to any of tested concentrations (1, 5, 25, 125 ng/min). Also both females and males were significantly repelled by the highest concentrations (25 and 125 ng/min). Additionally, concentration of 5 ng/min proved to be repellent for females of H. rumicis.

Aza-m-Xylylene Diradical with Increased Steric Protection of the Aminyl Radicals.

Aminyl diradical 3, a derivative of aza-m-xylylene, is expected to be more stable than diradical 1, due to increased steric protection of the radicals by additional methyl groups in the pendant group. Here we report synthesis and characterization of diradical 3. The structure of diamine precursor 6 is characterized by high-field (1)H NMR spectroscopy in which the two diastereomers (meso and ± pair) are distinguishable. In addition, correlation between the DFT-calculated and experimental (1)H and (13)C NMR chemical shifts provides evidence in support of the diamine structure. Electrochemistry of the diamine is carried out to explore redox properties and stability of the corresponding aminium diradical dications. The ground state and ΔEST for 3 are established by statistical analyses of mean χT determined by EPR spectroscopy. Decay kinetics of aminyl diradical 3 indicates that the decay of 3 is faster than that of 1, possibly due to intramolecular hydrogen atom abstraction from benzylic methyl groups in 3, followed by intermolecular hydrogen atom abstraction from 2-MeTHF solvent.

Monodispersed poly(4-vinylpyridine) spheres supported Fe(III) material: An efficient and reusable catalyst for benzylic oxidation

A novel ferric chloride immobilized poly(4-vinylpyridine) (P4VP) catalyst was developed via a coordination chemistry-based approach. The pyridine moiety of poly(4-vinylpyridine) spheres functioned as the nitrogen donor to bind iron ions, as well as to decrease the amount of pyridine used in the catalytic reaction system. The monodispersed catalyst was well dispersed in the organic solvent during the catalytic procedure, taking advantage of its nanomorphology and uniform size. The catalytic activity of various monodispersed catalysts based different mass fractions of the divinylbenzene (DVB) was investigated, meanwhile the capacities of supported Fe(III) in the various catalysts were also discussed. The P4VPDVB10%-Fe(III) catalyst exhibited high catalytic activity in the benzylic oxidation of benzylic methylenes and secondary benzylic alcohols. It was easily separated from the reaction system and reused several times without obvious degradation of catalytic activity. Moreover, leaching tests suggested that the as-synthesized P4VPDVB10%-Fe(III) catalyst was a true heterogeneous catalyst without significant metal leaching.

ChemInform Abstract: 1,3‐Dicyclohexylimidazol‐2‐ylidene as a Superior Ligand for the Nickel‐Catalyzed Cross‐Couplings of Aryl and Benzyl Methyl Ethers with Organoboron Reagents.

AbstractThe developed reaction system is inapplicable to secondary benzylic ethers other than 2‐[methoxy(phenyl)methyl]naphthalene (IX).

1-Alkyl-1-methylpiperazine-1,4-diium salts: Synthetic, acid–base, XRD-analytical, FT-IR, FT-Raman spectral and quantum chemical study

We report the preparation and results of vibrational spectral analysis, which were obtained using both FT-IR and FT-Raman spectroscopy, for three 1-alkyl-1-methylpiperazine-1,4-diium salts (AMPSs), where alkyl is benzyl 4a, n-octadecyl 4b, and methyl 4c, respectively. These were prepared by multistep synthesis from piperazine. The acid–base study of AMPSs was performed and corresponding acid–base constants were obtained. Single crystals of AMPSs suitable for XRD-analysis were obtained and analyzed. The complete vibrational assignments of wavenumbers were made on the basis of a potential energy distribution. The HOMO and LUMO analysis was used to determine the charge transfer within the molecules. The calculated first hyperpolarizabilities of AMPSs 4a–4c are 48.34, 57.77 and 123.41 times that of urea. As can be seen from the MEP plots, the negative electrostatic potential regions are mainly localized over the chlorine and oxygen atoms for compounds 4a and 4b and chlorine and iodine atoms of compound 4c, and are possible sites for electrophilic attack.

A Diaminoterephthalate–C60 Dyad: A New Material for Optoelectronic Applications

Diaminoterephthalate was used for the first time as a chromophore in a dyad with [60]fullerene. The synthesis was accomplished from the benzyl methyl diester by hydrogenolytic cleavage of the benzyl group, re-esterification with a benzyl alcohol with protected formyl function, deprotection of the latter and final 1,3-dipolar cycloaddition with C60 and sarcosine via the azomethine ylide.

Amphetamine in illegally produced phenylethylamine – intentional action or failed synthesis of a designer drug

On the Polish „drug scene”, the products containing very low amounts of amphetamine offered as „pure” amphetamine are increasingly common. Occasionally, 1-phenylethylamine (1-PEA) is added to these products. The concentration of 1-PEA in such „street drugs” usually ranges from 2% to 90%. For the purposes of the ongoing prosecutor’s proceedings, toxicological testing was performed in the Department of Forensic Medicine, Medical University of Lublin to detect narcotic agents and psychotropic substances in the white powder found in 23 plastic bags. LC/MS with atmospheric pressure chemical ionization method demonstrated only trace amounts of amphetamine and about 0.042–0.231% of 1-PEA in the samples analyzed. However, characteristic by-products of the synthesis of 1-phenylethylamine from acetophenone were indentified using GC/MS with electron ionization method. Results suggest that the analyzed „street drugs” were obtained by synthesis from acetophenone with slight amounts of benzyl methyl ketone (BMK) added intentionally, or using acetophenone contaminated with BMK.

ChemInform Abstract: Transition‐Metal‐Free Tandem Oxidative Removal of Benzylic Methylene Group by C—C and C—N Bond Cleavage Followed by Intramolecular New Aryl C—N Bond Formation under Radical Conditions.

AbstractThe novel tandem oxidative transformation of dibenzodiazepines to phenazines proceeds under transition‐metal‐free and mild conditions in the presence of K2S2O8 or DDQ as the oxidizing agent.

Practical synthesis of anti-β-hydroxy-α-amino acids by Pd(II) -catalyzed sequential C(sp(3) )-H functionalization.

An improved and practical procedure for the stereoselective synthesis of anti-β-hydroxy-α-amino acids (anti-βhAAs), by palladium-catalyzed sequential C(sp(3) )-H functionalization directed by 8-aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β-methyl C(sp(3) )-H of alanine derivative, β-acetoxylation of both alkylic and benzylic methylene C(sp(3) )-H bonds affords various anti-β-hydroxy-α-amino acid derivatives. As an example, the synthesis of β-mercapto-α-amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β-branched α-amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side-chain AAs, which could be explained by the competition of intramolecular C-OAc bond reductive elimination from Pd(IV) intermediates vs. intermolecular attack by an external nucleophile (AcO(-) ) in an SN 2-type process.

Tiliabisflavan A, a New Flavan‐3‐ol Dimer from Tilia amurensis with Cytotoxic and Anti‐Inflammatory Effects

In the search for anticancer compounds from Korean medicinal plants, themethanolic extract from the trunk ofTilia amurensis Rupr. (Tiliaceae) was found to have significant cytotoxicity against A549 (lung carcinoma), SK-OV-3 (ovary malignant ascites), SK-MEL-2 (skinmelanoma), andHCT-15 (colon adenocarcinoma) in our screening test. T. amurensis is commonly known as “bee tree” and widely distributed in the mountainous areas of Korea, China, and Japan. T. amurensis has been used to treat various diseases as a Korean traditional medicine from ancient times. Its flowers have been applied for alleviating a fever, and its leaves have also been traditionally used for analgesia and rheumatoid arthritis. Importantly, an extract of this tree has been used to treat stomach cancer without any side effects. A recent pharmacological study revealed the potential of T. amurensis as an anticancer agent by evaluating the DNA topoisomerase inhibitory activity. However, only a few constituents associated with the anticancer activity from T. amurensis have been reported. Recently, our phytochemical investigations on T. amurensis revealed the presence of bioactive lignan constituents with antitumor and anti-inflammatory activities. Our continuing interest in further research on the bioactive constituents from T. amurensis led us to investigate bioactive metabolites of T. amurensis trunk. A bioassay-guided fractionation and chemical investigation of its MeOH extract resulted in the isolation and identification of four flavan-3-ols, including a new flavan-3-ol dimer, tiliabisflavanA (1) (Figure 1). The isolated compounds were evaluated for their antiproliferative activities against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines, as well as their inhibitory effects on NO production in a lipopolysaccharide (LPS)-activated BV-2 cell line. Compound 1 was obtained as a colorless gum. The molecular formula of 1 [ α 1⁄2 25 D +31.5 (c 0.35, MeOH)] was determined to be C31H28O12 based on positive high-resolution electrospray ionization mass spectrometry (HR-ESIMS) data (m/z 615.1479 [M +Na], calcd for C31H28NaO12, 615.1478). The infrared (IR) spectrum showed absorption bands for hydroxyl group (3358 cm) and aromatic rings (1614 and 1450 cm). The structure of 1 was further elucidated by detailed analysis of H and C NMR chemical shifts and by heteronuclear multiple-quantum correlation (HMQC) and heteronuclear multiple-bond correlation (HMBC) experiments. The H and CNMR spectra of 1were similar to those of2 except for the particular signals assigned tomethylene carbon [δH 3.88 (s); δC 15.5]. The assigned proton and carbon resonances of 1 in CD3OD are summarized in Table 1. The H, C NMR, and HMQC spectra of 1 displayed the characteristic signals for theC-ring of flavan-3-ol [δH4.75 (br s,H-2), 4.10 (br s, H-3), 2.82 (dd, J = 16.5, 4.5, H-4a), and 2.67 (dd, J = 16.5, 3.5, H-4b); δC 79.2 (C-2), 66.0 (C-3), and 27.7 (C-4)]. In addition, the 1,3,4-trisubstituted B ring signals [δH 6.94 (d, J = 1.5,H-20), 6.72 (overlap,H-50, H-60); δC144.7 (C-30, C-40), 130.5 (C-10), 118.5 (C-60), 114.7 (C-50), and 114.2 (C-20)] were observed, together with the A-ring carbon signals [δC 154.6 (C-5), 154.0 (C-7), 152.4 (C-9), 105.5 (C-8), 99.3 (C10), and 95.6 (C-6)]. The NMR data were closely related to those of 2; however, instead of the two A ring aromatic methines (C-6, C-8) in 2, the NMR spectra of 1 showed only one aromatic methine (δC 95.6, CH) for the A ring and an additional quaternary aromatic carbon (δC 105.5, C) as well as particular benzylic methylene signals [δH 3.88 (s); δC 15.5 (CH2)]. This indicated that compound 1 is comprised symmetrically of two epicatechin units connectingC-6 andC-8 positions through amethylene bridge. In theHMBCspectrum (Figure 2), the CH2 proton signal at δH 3.88 showed HMBC correlations with δC 154.0 (C-7), 152.4 (C-9), and 105.5 (C-8), which revealed that the two epicatechin units in 1 were linked between their C-8 position through amethylenebridge.Theother partial structures of 1 were clearly elucidated by the interpretation of the H–H correlation spectroscopy (COSY) and HMBC, and thus, the gross structure of 1 was established as shown in Figure 1 and named tiliabisflavan A. The relative configurations of C-2 and C-3 in 1 were determined to be cis for (2R,3R) or (2S,3S) configuration [δC 79.2 (C-2)/66.0 (C-3) and J3,4a = 4.5 Hz, J3,4b = 3.5 Hz for 1] on the basis of the comparison with the chemical shifts of C-2/ C-3 [δC 79.9/67.5 for (+)-epicatechin (2) and δC 82.6/68.7 for (+)-catechin (3)] and the coupling constants of H-3/H-4 Note DOI: 10.1002/bkcs.10011 K. H. Kim et al. BULLETIN OF THE KOREAN CHEMICAL SOCIETY

Metal catalyzed cross-coupling of aryl and benzyl methyl sulfides: nickel catalyzed Caryl–Csp3 and Csp3–Csp3 bond formations

The nickel catalyzed functionalization of CAr–SMe and Csp3–SMe bonds by direct exchange of the sulfur atom with an activated sp3-carbon has been developed. The protocol allows the conversion of aryl and benzyl methyl sulfides to trimethylsilylated products in good yields.

A general Pd-catalyzed α- and γ-benzylation of aldehydes for the formation of quaternary centers.

A palladium-catalyzed benzylation of α-branched aldehydes has been developed using benzyl methyl carbonates. The method gives access to congested quaternary centers in the vicinity of one of the most sensitive carbonyl functionalities and displays unprecedented generality with respect to both coupling partners. Evidence for the direct involvement of a Pd-η(3)-benzyl intermediate is provided. Extension of this strategy to the γ-benzylation of α,β-unsaturated aldehydes is further demonstrated.

Study on Solvation Behavior of Benzyl Methyl Ammonium Carboxylate Ionic Liquids in N,N-Dimethylformamide by Physicochemical Properties

Two novel ionic liquids, benzylmethylammonium propionate and benzylmethylammonium hexanoate, were synthesized and the densities (ρ) speeds of sound (u) and viscosities (η) of their mixtures with N,N-dimethylformamide (DMF) in the concentration range of 0.067–0.573 mol·kg−1 were measured at 293.15–328.15 K. The relative viscosity (η r) and viscosity B-coefficients were calculated from measured viscosity data. Apparent molar volumes, V ϕ , and compressibilities, K s,ϕ have been calculated from experimental density and speed of sound data and the corresponding values at infinite dilution are estimated by the Redlich–Mayer equation. The results have been interpreted in terms of interaction of the ionic liquids with the organic solvent. The calculated apparent molar volume at infinite dilution (V ϕ ∞ ) values indicate that ionic liquid–molecular solvent interactions are stronger for benzylmethylammonium hexanoate in DMF than the benzylmethylammonium propionate in DMF mixtures. The limiting apparent molar expansibilities, E ϕ ∞ , at each temperature for both binary solutions have positive values and increase with increasing temperature.

Ceric ammonium nitrate oxidation of N-(p-methoxybenzyl)lactams: competing formation of N-(hydroxymethyl)δ-lactams

The ceric ammonium nitrate mediated oxidative deprotection of N-(p-methoxybenzyl) δ-lactams leads to the formation of an unexpected N-(hydroxymethyl) δ-lactam along with the Ndeprotected δ-lactam. In comparison, N-(p-methoxybenzyl) γ-lactams are completely deprotected under the same reaction conditions. Further studies indicated that addition of an aqueous solution of ceric ammonium nitrate to an acetonitrile solution of N-(p-methoxybenzyl) δ-lactams in the presence of 2-amino-2-methyl-1-propanol as an additive promoted N-deprotection. Ceric ammonium nitrate oxidation of N-(α,α-dideuterio-p-methoxybenzyl)-6-allyl-δ-lactam (8), revealed that the methylene unit of the N-(hydroxymethyl) group is derived from the benzylic methylene unit of the N-protecting group. A plausible reaction pathway for the formation of the N-(hydroxymethyl) δ-lactams from an N-acyliminium ion intermediate is proposed.