Hemlock Tsuga

The Native Lignin from Western Hemlock Tsuga heterophylla). J. org. 

This paper is a report on preliminary studies evaluating the suitability of bark extracts from four West Coast softwood species as bonding agents for particleboard. The barks investigated include white fir (Abies concolor), ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) ... 

In kraft pulping the substitution of Thuja plicata for western hemlock, Tsuga heterophylla, led to increased digester corrosion (Gardner and Hillis, 1962). It was shown that steam-volatile tropolones known as thujaplicins were responsible for corrosion at the top of the digesters, and that polyphenols with a catechol group, which have a tendency to complex with iron, were responsible for the remainder of the corrosion. 

HERBS IN MAGIC AND ALCHEMY Hemlock Tsuga canadensis (Spruce)... 

Polcin and Rapson [12] have shown that hydrosulfite predominantly attacks simple quinoid, a,p-unsaturated aldehyde and anthocyanidine structures found in groundwood pulps prepared from western hemlock (Tsuga heterophylla) and eastern spruce (Picea glauca). A few years later, de Vries et al. [13,14] have demonstrated that hydrosulfite can reduce many types of aldehydes and ketones in solution according to the mechanism shown in Figure 13.1. Ketones were found to react sluggishly in water, esters are hydrolyzed, while carboxylic acids and amines are not reduced. 

Pinus tahda Loblolly pine Tsuga heterophylla Western hemlock Tsuga heterophylla... 

Mannose-containing Hemicelluloses in the Wood of Eastern Hemlock (Tsuga canadensis) ... 

Canadian hemlock Tsuga canadensis (L.) Carrttre P. apterus Sth instar larvae Topical +++ 83... 

Honey locust Gleditsia tricanthos L.) 21 Eastern hemlock (Tsuga Canadensis L. Carr) 33... 

C12H22O11 342.299 Structural unit in the glucomannans of plant hemicelluloses. Isol. from the partial acid hydrolysates of the glucomannans from Amorphophallus spp., white spruce (Pinus glauca), western hemlock (Tsuga heterophylla), red maple (Acer rubrum), eastern white pine (Pinus strobus), larch (Larix decidua), jack pine (Pinus bank-siana) and from Narcissus tazetta from hemicelluloses of lobolly pine (Pinus taeda) and in trace amounts from the acetolysates of the a-celluloses from white birch (Betula papyrifera) and slash pine... 

Isol. from the partial acid hydrolysates of white spruce (Picea glauca), western hemlock (Tsuga heterophylla), jute fibre, maritime pine (Pinus pinaster), aspen (Populus tremuloides) hemicelluloses. 

Two examples are illustrative Shortly after the turn of the century, one of the ten largest companies in the United States was totally dependant upon extractives for its raw material (23). The Central Leather Company, successor to the United States Leather Company, had tanneries scattered all over the state of Pennsylvania, each of which extracted tannin from the bark of the eastern hemlock Tsuga canadensis). Today not only is it the only one of the ten companies no longer in existence, but there is not a single producer of native tannin in North America. 

Hemicelluloses from many woods, particularly conifers (softwoods) contain glucomannoglycans which may be isolated by fractionation procedures. The glucomannoglycan from western red cedar [Thuja plicata Donn) is a typical example. It contains D-glucose and D-mannose only, in the ratio 2 5, and is a short-chain, essentially linear, /S-d-(i - 4)-linked polymer. Similar glucomannoglycans have been isolated from western hemlock [Tsuga heterophylla), sitka spruce (Picea sitchensis) and other softwoods. Glucomannoglycans from Norwegian spruce (Picea aHes) are a-D-(i - 4)-Unked. 

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