A new route for the functionalisation of wood through transesterification reactions

A novel transesterification reaction between acetylated maritime pine sapwood (Pinus pinaster Soland) and methyl benzoate (MB), in the presence of dibutyltin oxide (DBTO) as a catalyst, was performed. Reaction was confirmed by Fourier-transform infrared spectroscopy (FTIR) and ¹³C nuclear magnetic resonance cross-polarisation with magic-angle spinning (NMR CP MAS) analysis: signals corresponding to benzoylated wood were identified and, when transesterification was performed with ethyl trimethylsilylacetate (ETMSA), characteristic trimethylsilyl groups were detected. The acetyl/benzoyl exchange rate was found to increase with increasing amount of DBTO, temperature and reaction time and a concurrent deterioration of the woody material was evidenced.     

Zur Reaktion von 1,3-Oxazolidinen mit Dicarbonsäureanhydriden

Reaction of 3-methyl-1,3-oxazolidine with phthalic anhydride in chloroform leads to ring opening and higher oligomers2 are formed. These are cleaved by addition of protic solvents and 2-methylaminoethyl hydrogenphthalate3 a is obtained. Other 1,3-oxazolidines and succinic anhydride behave similarly.

Herrn Prof. Dr. Dr. h. c.Karl Kratzl mit den besten Wünschen zum 70. Geburtstag gewidmet.     

A study for quality evaluation of Taxilli Herba from different hosts based on fingerprint-activity relationship modeling and multivariate statistical analysis

In this study, a fingerprint-activity relationship modeling between chemical fingerprints and antirheumatic activity was established, and multivariate statistical analysis was used to evaluate the quality of Taxilli Herba (TH) from different hosts. Characteristic fingerprints of 20 batches of TH samples were generated by high-performance liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (HPLC-Triple TOF-MS/MS), and the similarity analysis was calculated based on thirteen common characteristic peaks by hierarchical clustering analysis (HCA). Subsequently, nine efficacy markers were discovered by combining fingerprints and antirheumatic activity through grey correlation analysis (GCA) and bivariate correlation analysis (BCA). Meanwhile, the content of 5 constituents in 9 markers was determined by high-performance liquid chromatography coupled with triple quadrupole-linear ion trap tandem mass spectrometry (HPLC-QTRAP-MS/MS). The comprehensive quality of TH was assessed using multivariate statistical analysis, including principal components analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS). The results showed that a high dose of TH extract could markedly ameliorate arthritis damage compared to other doses, with flavonoids playing an important role in the antirheumatic activity. The comprehensive quality of samples from Morus alba L. (SS) was superior to those from Liquidambar formosana Hance (FXS). The present study will demonstrate the markers associated with efficacy, and provide an applicable strategy for more comprehensive quality control and evaluation of TH.     

Die stufenweise Syntheseo,o′-methylenverbrückter Cyclohexamerer mitp-Kresol- oderP-Kresol- und 4-tert-Butylphenol-Bausteinen Vergleich mit ähnlich strukturierten Kettenoligomeren

Two phenolic alcohols with six phenolic units in their molecules have been obtained by stepwise syntheses starting from simple phenolic derivatives. The phenolic alcohols were cyclized in a one step cyclization by boiling in a very diluted acetic acid solution. A two step cyclization of a phenolic alcohol with three phenolic units to a cyclohexamer proceeds only with poor yields. The cyclic compounds were compared with chainlike oligomers containing six phenolic units in their molecules.

Herrn Prof. Dr.H. F. Mark mit allen guten Wünschen zum 85. Geburtstag gewidmet.     

Stereoselective synthesis of (±)-indolizidines 167B and 209D and theirtrans-isomers based on the reductive allylboration of pyridine

A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization oftrans- andcis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in the presence of the Ph₃P−CBr₄−Et₃N system. (Pr₂BH)₂ and Pr₃B are used as the hydroborating reagents, and H₂O₂ in an acid medium is used for the oxidation of 2-[3-(dipropylboryl]-Δ²-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and itstrans-isomer were prepared fromcis- andtrans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B andtrans-5-propylindolizidine were synthesized fromcis- andtrans-2,6-diallyl-1,2,3,6-tetra-hydropyridine, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 971–979, May, 1998.     

Fluctuation-dominated kinetics in the a+b→0 reaction between immobile particles

We consider the accumulation of immobile particles landing on a one-dimensional lattice and annihilating via the A + B 0 bimolecular reaction. Here we focus on short-range interactions with cutoff. We investigate through computer simulations both the kinetics of the particles' accumulation and also their spatial distribution. The relation between the exponents describing the growth of the particles' concentration and the correlation length of their distribution shows that the kinetics of accumulation is fluctuation-dominated.This work is dedicated to Prof. George H. Weiss.     

Search for νμ and ντ supernova neutrinos with massive liquid-scintillation detectors

Summary In this paper we have estimated the sensitivity of a large-mass liquid-scintillation detector to search for supernova neutrinos of different flavours. Events produced by ν_μ and ν_τ interactions can be identified by looking at the distorsion in the neutrino energy spectrum. We have shown here that, overlapped to the main energy distribution produced by interactions with protons a peak at 15.11 MeV (due to the de-excitation of¹²C^* nuclei excited by neutral-current neutrino interactions) gives a possible signature of these neutrino flavours. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

Synthesis of Heterocycles from the Products of Anionic Arylation of Unsaturated Compounds. 7. Products of Haloarylation of Acrylic Acid and Its Esters in the Synthesis of Benzo[b]thiophene Derivatives

3-Chloro-2-chlorocarbonylbenzo[b]thiophenes were obtained on oxidation of Meerwein reaction products, viz. 3-aryl-2-halopropionic acids and their esters, with thionyl chloride in the presence of N-benzyl-N-methylmorpholinium chloride. Disubstituted thioureas were synthesized by the reaction of these compounds with ammonium thiocyanate and aromatic amines, and were cyclized by interaction with iodoacetic acid with the formation of 4-thiazolidinone derivatives. The same cyclization in the presence of aromatic aldehydes leads to the formation of the corresponding 5-arylidene-substituted 4-thiazolidinones.     

Simple test system for single molecule recognition force microscopy

We have established an easy-to-use test system for detecting receptor-ligand interactions on the single molecule level using atomic force microscopy (AFM). For this, avidin-biotin, probably the best characterized receptor-ligand pair, was chosen. AFM sensors were prepared containing tethered biotin molecules at sufficiently low surface concentrations appropriate for single molecule studies. A biotin tether, consisting of a 6 nm poly(ethylene glycol) (PEG) chain and a functional succinimide group at the other end, was newly synthesized and covalently coupled to amine-functionalized AFM tips. In particular, PEG₈₀₀ diamine was glutarylated, the mono-adduct NH₂-PEG-COOH was isolated by ion exchange chromatography and reacted with biotin succinimidylester to give biotin-PEG-COOH which was then activated as N-hydroxysuccinimide (NHS) ester to give the biotin-PEG-NHS conjugate which was coupled to the aminofunctionalized AFM tip. The motional freedom provided by PEG allows for free rotation of the biotin molecule on the AFM sensor and for specific binding to avidin which had been adsorbed to mica surfaces via electrostatic interactions. Specific avidin-biotin recognition events were discriminated from nonspecific tip-mica adhesion by their typical unbinding force (∼40 pN at 1.4 nN/s loading rate), unbinding length (<13 nm), the characteristic nonlinear force-distance relation of the PEG linker, and by specific block with excess of free d-biotin. The convenience of the test system allowed to evaluate, and compare, different methods and conditions of tip aminofunctionalization with respect to specific binding and nonspecific adhesion. It is concluded that this system is well suited as calibration or start-up kit for single molecule recognition force microscopy.     

Infrared spectroscopic study of the interactions of nylon‐6 with water

We studied the interactions of nylon‐6 with water by following the Fourier transform infrared spectra of a hydrated thin film during dehydration. Very small changes in the spectra caused by the interactions were clearly revealed by the application of spectral subtraction. The water was found to interact with amide groups to form hydrogen bonds with non‐hydrogen‐bonded or free C?O and NH groups in the amorphous portion in the first hydration sphere. This was deduced from an analysis of minus and plus peaks appearing around the absorptions of the NH stretching, amide I band, and amide II bands in the difference spectra between the spectra during dehydration and the one at the most dehydration. The interactions of the amide groups with water were significantly stronger than the hydrogen bond between CO and NH in the crystalline portion, according to the magnitude of the frequency shift of relevant bands. Water, as the interacting counterpart, showed a distorted OH stretching absorption with two close peaks at about 3450 cm^?1. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1722–1729, 2003