Furnish preparation

Processes used to manufacture softboards and hardboards are basically similar and readily divisible into a furnish-preparation phase and a board-conversion phase. Hardboard processes differ in that board conversion uses pressure to densify the sheet whereas softboard processes do not. Both processes subject the felted sheets to high temperatures in the board-conversion phase. Hardboard processes use more severe conditions and effect more extensive physical and chemical changes consequently, these processes offer more insight into chemical changes associated with board manufacture. 

Three major furnish preparation processes (Figure 1) are now in use today. These are the original Masonite wet-form process, the wet form process using pressurized refining, and the dry form process. 

The Masonite Wet-Form Process. Masonite Corpor-ation was founded to exploit Mason s patents and still practices the original furnish-preparation process shown schematically in Figure 1. Cooking is accomplished by charging chips into a vertical cylinder outfitted with a slotted plate at the bottom that supports the chip stack. Below the plate is an hydraulically-operated valve that provides passage to the atmosphere. 

Wood, and the fiber obtained from it, is a complex arrangements of polymers and macromolecules that are exceedingly difficult to analyze chemically. But it is shown in Figure 1 that wet processes produce two streams, pulp from cooked fiber for board production and a liquor containing water solubles extracted from the stock. The liquor is easier to analyze and its composition may afford insight into the chemical changes effected by furnish preparation. 

Figure 1. Process schematics for the typical furnish preparation (defibering) processes used in wood fiber-board manufacture...

Figure 10. Modulus of elasticity in bending as a function of specific gravity for wet/wet boards made from furnish prepared from a high steam-pressure cook (severe) and a mild cook...

Acetaldehyde oxidation to anhydride does not consume great amounts of energy. The strongly exothermic reaction actually furnishes energy and the process is widely used in Europe. Acetaldehyde must be prepared from either acetylene or ethylene. Unfortunately, use of these raw materials cancels the other advantages of this route. Further development of more efficient acetaldehyde oxidation as weU as less expensive materials of constmction would make that process more favorable. 

Anthralin [1143-38-0] is acetylated using acetyl chloride in toluene and a pyridine catalyst to furnish 1,8-dihydroxy-lO-acetylanthrone [3022-61-5], an intermediate in the preparation of medications used in treating skin disorders, such as warts, psoriasis, and acne (38). Sugar esters can be similarly prepared from acetyl chloride under anhydrous conditions (39). 

It is possible to prepare very heavy elements in thermonuclear explosions, owing to the very intense, although brief (order of a microsecond), neutron flux furnished by the explosion (3,13). Einsteinium and fermium were first produced in this way they were discovered in the fallout materials from the first thermonuclear explosion (the "Mike" shot) staged in the Pacific in November 1952. It is possible that elements having atomic numbers greater than 100 would have been found had the debris been examined very soon after the explosion. The preparative process involved is multiple neutron capture in the uranium in the device, which is followed by a sequence of beta decays. Eor example, the synthesis of EM in the Mike explosion was via the production of from followed by a long chain of short-Hved beta decays,... 

Subsequent to stock preparation and proper dilution, the paper furnish usually is fed to the paper machine through one or more screens or other devices to remove dirt and fiber bundles. It then enters a flow spreader which provides a uniform flowing stream and which is the width of the paper machine. The flow spreader, or manifold, discharges the slurry into a headbox, where fiber flocculation is minimised by microturbulence and where the proper pressure head is provided to cause the slurry to flow at the proper velocity through the slice and onto the moving Fourdrinier wire. 

To synthesize the monoxacetam stmctures (Fig. 6), alkylation of A/-protected 1-hydroxyazetidinones (46) with the appropriate haloacetic acid derivatives provided (47). Alternatively, (47) could be prepared from the acycHc hydroxamate ester (48). Deprotection of (47) furnished the zwitterionic intermediate (49) [90849-16-4] CgH2QN204, which subsequendy underwent acylation using the C-3 aminothiazole oxime side chain to afford SQ 82,291 (45) also known as oximonam (37). 

The preparation of benzo fused pyrido[3,2- i]pyrimidines has furnished the only examples of the classic reaction of this type, the Bischler-Napieralski, involving the cyclization of 5-aryl-4-acylaminopyrimidines to 6-alkylpyrimido[4,5-c]isoquinolines, e.g. (157)->(158) (73YZ330). As often found in this reaction, the presence of activating substituents appears necessary (78CPB245). 

The use of guanidine for cyclization gives amino substituted derivatives (e.g. 212) (52CB1012), and in this case o-aminonitriles may be used to furnish diamines (e.g. 8UOC1394). An unusual reaction involving nitriles occurred during the preparation of nicotinonitrile from the amide and ammonium sulfamate, when a 60% yield of the dimeric by-product (213) was formed via the nitrile (69BSB289). Similar products have been obtained from... 

The addition of phthalimidylnitrene (374) to simple alkynes affords 1-azirines in yields of 1-15% (Scheme 10). In this reaction, which is of no real preparative value, the symmetrical 2-azirines (375) were suggested as the most plausible intermediates and unequivocal proof of the existence of such species was demonstrated from a series of 1,2,3-triazole pyrolysis reactions <71CC1518). Extrusion of nitrogen from the regioisomeric 4,5-disubstituted 1,2,3-triazoles (376) during flash vacuum pyrolysis furnished identical product mixtures which included both regioisomeric 1-azirines (377). 

This complex should be used when the organolithium is in solution in a hydrocarbon solvent. For organolithium reagents prepared in ether (see Note 4), the same complex may be used or, more conveniently, copper iodide (Cull can be used. The Cul purchased from Prolabo or Merck 4 Company, Inc. may be used directly. Other commercial sources of Cul (Fluka, Aldrich Chemical Company, Inc., Alfa Products, Morton/Thiokol, Inc.) furnish a salt which affords better results when purified. 1 mol of Cul is stirred for 12 hr with 500 ml of anhydrous tetrahydrofuran, then filtered on a sintered glass funnel ( 3), washed twice with 50 ml of anhydrous tetrahydrofuran, once with 50 ml of anhydrous ether and finally dried under reduced pressure (0.1 imO for 4 hr. 

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