Stereoselective glycosylations using oxathiane spiroketal glycosyl donors

Novel oxathiane spiroketal donors have been synthesised and activated via an umpolung S-arylation strategy using 1,3,5-trimethoxybenzene and 1,3-dimethoxybenzene. The comparative reactivity of the resulting 2,4,6-trimethoxyphenyl (TMP)- and 2,4-dimethoxyphenyl (DMP)-oxathiane spiroketal sulfonium ions is discussed, and their α-stereoselectivity in glycosylation reactions is compared to the analogous TMP- and DMP-sulfonium ions derived from an oxathiane glycosyl donor bearing a methyl ketal group. The results show that the stereoselectivity of the oxathiane glycosyl donors is dependent on the structure of the ketal group and reactivity can be tuned by varying the substituent on the sulfonium ion

Thermal capacitator design rationale. Part 1: Thermal and mechanical property data for selected materials potentially useful in thermal capacitor design and construction

The thermal properties of paraffin hydrocarbons and hydrocarbon mixtures which may be used as the phase change material (PCM) in thermal capacitors are discussed. The paraffin hydrocarbons selected for consideration are those in the range from C11H24 (n-Undecane) to C20H42 (n-Eicosane). A limited amount of data is included concerning other properties of paraffin hydrocarbons and the thermal and mechanical properties of several aluminum alloys which may find application as constructional materials. Data concerning the melting temperature, transition temperature, latent heat of fusion, heat of transition, specific heat, and thermal conductivity of pure and commercial grades of paraffin hydrocarbons are given. An index of companies capable of producing paraffin hydrocarbons and information concerning the availability of various grades (purity levels) is provided

ANALYSIS OF FICUS CARICA L. – VOLATILE COMPONENTS AND MINERAL CONTENT

Ficus carica L. is a well-known Mediterranean plant, its fructus - the fig- is consumed widely, mostly in the southern region of Europe. It’s a member of the Moraceae family, one of the earliest crops. It can be consumed raw, dried or even as jam as a part of the Mediterranean diet. One part of our research was to determine the volatile components of Ficus carica L. The composition of volatile components are important for the determination of fruit quality. We compared two extraction methods, examined by SPME-GC/MS. Two preparation methods were used: directly measured by SPME, and also samples made by steam distillation. Figs has an important role as phytonutrition. Mineral element content was determined by ICP. Fig is a good source of elements for Ca, Cr, Cu, Fe, K, Mg, Mn and Mo, since eating 5 dkg of dried fig covers more than 15% of the Recommended Dietry Allowances

Synthesis of 2,4,8,10-tetroxaspiro5,5undecane

Pentaerythritol is converted to its diformal, 2,4,8,10-tetroxaspirol5.5undecane, by heating it to a temperature within the range of about 110 to 150 C, for a period of up to 10 minutes, in the presence of a slight excess of paraformaldehyde and of a catalytic quantity of an acid catalyst such as sulfuric acid. The reaction may be carried out in two steps, by forming first the monoformal, then the diformal. In any case, total reaction time is about 10 minutes, and yield of diformal are greater than 90%. Previous processes require hours or days, and often, tedious operating procedures

Molecular Actuator: Redox-Controlled Clam-Like Motion in a Bichromophoric Electron Donor

The one-electron oxidation of tetramethoxydibenzobicyclo[4.4.1]undecane (4) prompts it to undergo a clam-like electromechanical actuation into a cofacially π-stacked conformer as established by (i) electrochemical analysis, (ii) by the observation of the intense charge-resonance transition in the near IR region in its cation radical spectrum, and (iii) by X-ray crystallographic characterization of the isolated cation radical salt (4+• SbCl6−)

The Impact of Gravity and Molecular Diffusion on the Compositional Gradient in Gas Reservoirs

Imperial Users onl

Photochemical synthesis of a “cage” compound in a microreactor: Rigorous comparison with a batch photoreactor

An intramolecular [2 + 2] photocycloaddition is performed in a microphotoreactor (0.81 mL) built by winding FEP tubing around a commercially available Pyrex immersion well in which a medium pressure mercury lamp is inserted. A rigorous comparison with a batch photoreactor (225 mL) is proposed by means of a simple model coupling the reaction kinetics with the mass, momentum and radiative transfer equations. This serves as a basis to explain why the chemical conversion and the irradiation time are respectively increased and reduced in the microphotoreactor relative to those in the batch photoreactor. Through this simple model reaction, some criteria for transposing photochemical synthesis from a batch photoreactor to a continuous microphotoreactor are defined