Of dextrins

Arai and Ise91 carried out the acid hydrolyses of dextrin in the presence of copolymers of vinylalcohol and vinylsulfuric acid, 39 (PVS VA). Figure 10 shows... 

Fig. 10. Plots of the relative rate constants of the hydrolysis of dextrin vs. the mole ratio of vinylalcohol unit to vinylsulfonic acid unit, o PVS VA, Polyvinylalcohol + HPVS (Ref.

An expl prepd by mixing Ba nitrate, diarcoal and Amm picrate or amorph P 1888 An expl consisting of 3p Ba nitrate and lp AN, together with a small quant of dextrin or gum as binder... 

Commercially, lead azide is usually manufactured by precipitation in the presence of dextrine, which considerably modifies the crystalline nature of the product. The procedure adopted is to add a solution of dextrine to the reaction vessel, often with a proportion of the lead nitrate or lead acetate required in the reaction. The bulk solutions of lead nitrate and of sodium azide are, for safety reasons, usually in vessels on the opposite sides of a blast barrier. They are run into the reaction vessel at a controlled rate, the whole process being conducted remotely under conditions of safety for the operator. When precipitation is complete, the stirring is stopped and the precipitate allowed to settle the mother liquor is then decanted. The precipitate is washed several times with water until pure. The product contains about 95% lead azide and consists of rounded granules composed of small lead azide crystals it is as safe as most initiating explosives and can readily be handled with due care. 

The original initiating explosive used by Nobel and all manufacturers for many years was mercury fulminate. This had the disadvantage of decomposing slowly in hot climates, particularly under moist conditions. For this reason mercury fulminate is no longer widely used. In most countries it has been replaced by a mixture of dextrinated lead azide and lead styphnate. In the U.S.A. some detonators are made containing diazodinitrophenol. 

Glucose or maltose by selective fermentation with washed baker s yeast dextrine by difference. b Average degrees of polymerization of dextrine were calculated from their reducing values as follows ... 

Free aldehyde groups do not appear to be essential to the action of malted barley alpha amylase. Myrback82,83 reports that, like beta amylase,1 3 this amylase also causes the hydrolysis of dextrins after their aldehyde groups have been oxidized to the corresponding acids. 

Studies of the rate of the hydrolysis of dextrins isolated from a reaction mixture after the extensive hydrolysis of starch by maltase-free malted barley alpha amylase, led Myrback11 to conclude that the flattening of the reaction curves with this amylase is not due to equilibrium between the amylase and the products of the hydrolysis. As indicated above, similar conclusions have been reached for pancreatic amylase and for the amylase of Aspergillus oryzae.41,7a... 

This study also suggests that molecular size and structure play a role in this interaction. The binding behaviors of dextrin oligomers for four different pharmaceuticals (ibuprofen, ketoprofen, furosemide, and warfarin) were observed under the same experimental conditions. Ibuprofen and ketoprofen, two compounds that are similar in chemical structure and pharmaceutical use, showed obvious differences in interaction patterns (Fig. 13A and B). Ketoprofen, having an extra aromatic ring, required an octa-saccharide (DP = 8) for binding, whereas ibuprofen required a heptasac-... 

In the book of Fordham (Ref 51, p 108-09) are described Brit "plain detonators" such as No 6, which contains as a base chge 0.24g PETN and No 8 Star, which contains 0.8g PETN. As a priming charge, in both cases, a 2/1 mixt of dextrinated LA/LSt is used with ca 3% A1 powder and, sometimes, 3% Tetryl added... 

Sephadex G-75 water fractionation of dextrins from hydrolysis of starch 114... 

CDs are macrocyclic oligosaccharides built of a-D-g/wcopyranoside units interconnected by a-(M) bonds. They are obtained by enzymatic degradation of dextrins (Figure 7.4.2). The most important in this group of compounds 278a with n = 6, 7 and 8 bear the... 

The mixture can be made into beads. To do this, add to it thick starch size or a solution of dextrin in cold water until a thick dough is formed. Make beads 5 mm in diameter from it. Put the beads on a chamotte plate and dry them in a drying cabinet at a temperature of 100 °C. 

Preparation of Vanadium Oxychloride and Studying of Its Properties. Preparation of Vanadium Oxychloride by Roasting a Mixture of Vanadium(V) Oxide with Charcoal in a Chlorine Stream. Prepare a fine mixture of 5 g of vanadium(V) oxide, 3 g of charcoal, and 5 g of dextrin. Add water dropwise to the mixture until a paste... 

Evans and Yuill [97] investigated the ignition of dextrinated lead azide by the adiabatic compression of air surrounding it, and estimated that the 50% explosion level corresponds to a temperature of 990°C. 

Fig. 47. Lead azide for use in detonators (75 x ) precipitated in the presence of dextrin...

They also found that by adding small amounts of dextrin, polyvinyl alcohol or other hydrophilic polymers explosion could be prevented. It is known that these compounds are able to alter the crystal habit of several substances, including lead azide. 

Considerable progress in the manufacture and application of lead azide was achieved by the addition of dextrin to the solution in which it was produced, as mentioned above. 

The presence of dextrin in the solution favours the precipitation of tiny, equal sized, rounded crystals. In Fig. 47 magnified crystals of dextrinated lead azide are shown and in Fig. 48 crystals of ordinary lead azide are shown for comparison. According to Sudo [96] gelatine exerts an influence similar to that of dextrin. In this author s opinion when precipitated from a solution containing gelatine lead azide is less sensitive to friction than that from solutions without added colloids. 

Lead azide is manufactured on a technical scale by the action of sodium azide on an aqueous solution of lead nitrate. According to a description of manufacture in the Wolfratshausen factory in Germany [109], the reaction is conducted in an open reactor of stainless steel, provided with a jacket warmed by hot water and a stirrer which may be lifted out of the reactor (Fig. 49). The reactor is emptied by tilting. Its upper edge is therefore fitted with a spout so that the contents pour easily. The size of the reactor is such that 4.5 kg of lead nitrate in the form of a 9-10% solution can be used in each batch. This solution is poured into the reactor, warmed to 50°C and neutralized with sodium hydroxide to a pH of about 4.0 (in the presence of methyl orange) and 150 g of dextrin mixed with a small amount of water, is added. The suspension or solution of dextrin in water should be decanted before use to separate mechanical impurities, such as sand. 

N = normality of NaOH soln A = ml of NaOH soln used in the test B ml of NaOH soln used in the blank C = wt of dextrin in 100 ml filtrate... 

JACS 68, 374(1946) CA 40, 3634(1946) (Nitration of dextrin starches with N2O5 in presence of Na fluoride) 5) G.V. Caesar et al, JACS 69, 617-21 (1947) CA 41, 3680(1947) (MW detns intrinsic viscosities of nitric triesters of dextrins corn starches)... 

Carbohydrate-derived polymers may overcome these negative attributes (9), Previously published work (10-13) demonstrated the potential for improved functional characteristics of dextrinized, oxidized and native starches by simple... 

Dextrose Equivalency. Corn starch dextrose equivalent values (de) were usedto measure the carbonyl groups present in both dialdehyde, oxidized starch production and the production of dextrinized starches (26). 

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