Paul R. Steiner

C-Stannane derivatives of carbohydrates

Triphenyltin lithium (1) was reacted separately with 1,2:3,5-di-O-methylene-6-O-tosyl-α-D-glucofuranose (2), with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (4), and with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-mannopyranoside (6), to form in each case a sugar-stannane derivative having a stable carbon-tin bond. These products have been studied by 1H and 13C nmr spectroscopy.

Spatial structure of wood composites in relation to processing and performance characteristics

SummaryA rationale is presented for developing a mathematical model which describes a randomly packed, short-fibre-type wood composite. The model will utilize probability theory to insure random packing both in terms of flake position and orientation. Knowledge about the spatial relationship between wood elements will be used, in future, to predict a number of physical parameters associated with the composite structure. This will be accomplished by first developing a single-layer-flake model and subsequently proceeding to a multi-layer mat structure.

Some 3-C-(dimethoxy)phosphinyl derivatives of D-glucose, D-allose, and D-ribose

Abstract Reaction of 1,2:5,6-di- O -isopropylidene-α- D - ribo -hexofuranos-3-ulose with dimethyl phosphite affords preponderantly 3- C -(dimethoxy)phosphinyl-1,2:5,6-di- O -isopropylidene-α- D -allofuranose; lesser quantities of the C -3 epimer have also been isolated. The structural assignments of these derivatives are based on detailed n.m.r. analyses. A similar reaction has been applied to 1,2- O -isopropylidene-5- O -tosyl-α- D - erythro -pentofuranos-3-ulose to give 3-C-(dimethoxy)phosphinyl-1,2- O -isopropylidene-5- O -tosyl-α- D -ribofuranose.

On horizontal density variation in randomly-formed short-fibre wood composite boards

Abstract A mathematical model for characterizing horizontal density variation of a short-fibre wood composite panel is derived in terms of local point density variance V(D), point autocorrelation function η(Z,λ,ω) and variance of density averages between finite sampling zones V(Ď). The point density variance is the upper-bound of zone density variance as zone size become infinitely small. Assuming random mat formation, the model predicts how the horizontal density variation changes with fibre dimensions and other processing parameters. The zone density variance V(Ď) as a monotonically decreasing function of zone size is determined by global panel density, compaction ratio (panel-to-wood density ratio), thickness ratio (panel-to-element thickness ratio), and point-to-point density correlation function which, in turn, is a function of element width and length. According to the model prediction, V(Ď) is affected by element width, length and zone size in a highly interactive manner. While increasing width and length and decreasing zone size generally cause an increase in V(Ď), the extent to which V(Ď) changes with one parameter depends on the magnitude of others. The predictive results on how the zonal density variation is affected by the processing parameters are graphically presented and discussed.

Tannins as Specialty Chemicals: An Overview

Apart from their traditional use for leather manufacture and more recent applications as wood adhesives, tannins have seen limited success as specialty chemicals. Previous attempts to develop tannin-based chemicals have suffered because of our failure to appreciate fully economic requirements, purity and stability factors, and application needs of industrial processes. This chapter presents an overview of some of the chemical, physical, and structural features of tannins that have a bearing on future specialty chemical development. Information also is provided on areas where tannins have recently been utilized.