Gelatin reactions

After all the ethoxide has been added (twenty to thirty minutes) the gelatinous reaction mixture is stirred until no more distillate comes over (fifteen to thirty minutes). The weight of this distillate amounts to 38-45 g. (Note 5). 

Dolan et al. (1989) developed a model (Equations 4.34 and 4.35) to describe apparent viscosity as a function of time during starch gelatinization under non-isothermal conditions and additional discussion on its application to starch dispersions can be found in Dolan and Steffe (1990). The model contains an exponential function of the temperature-time history and the Arrhenius equation to describe the gelatinization reaction. The special form of the model for constant shear rate and starch concentration is ... 

The addition of 30-40 cc. of water to the gelatinous reaction mixture causes separation of a brown, partly crystalline precipitate. To minimize decomposition, the precipitate is quickly filtered, pressed dry and taken up in ethanol. Upon the addition of a little water and gentle warming, the solution separates into a lower dark brown layer (the sodium salt of methylene di-isonitramine) and the upper pale yellow alcoholic solution of base A and the sodium salt of a-A -methyl pyrrolidylacetic acid. 

Making objective measurements of these basic sensations is particularly complex. However, the gelatin index provides an estimate of reactivity to proteins. The intensity of the polyphenol-gelatin reaction depends on conditions in the medium. Acidity is a favorable factor, unlike alcohol content, which inhibits the reaction and gives a sweet taste. The reaction is independent of the tannin concentration at values above 50 mg/1 (Glories, 1983). Under given reaction conditions, it is thus possible to classify the various polyphenols according to their aptitude to combine. 

After 48 hours, the reaction was terminated by injection of 0.5 mL of aqueous, 1.0 wt % hydroquinone solution. The thick or gelatinous reaction mixture was scraped into a 1-L beaker using ceramic or plastic tools. The flask was washed with water, and the wash is placed in the beaker. This mixture was stirred until a thick, uniform solution has formed. Product was precipitated by dropwise addition of the product solution to five times its volume of vigorously stirred nonsolvent. 

Why is potassium aluminium sulphate not soluble in benzene A compound M has the composition C = 50.0% H=12.5%o A1 = 37.5%. 0.360 g of M reacts with an excess of water to evolve 0.336 1 of gas N and leave a white gelatinous precipitate R. R dissolves in aqueous sodium hydroxide and in hydrochloric acid. 20 cm of N require 40 cm of oxygen for complete combustion, carbon dioxide and water being the only products. Identify compounds N and R, suggest a structural formula for M, and write an equation for the reaction of M with water. (All gas volumes were measured at s.t.p.)... 

It is thought that the function of the glue or gelatin is to combine with very slight traces of heavy metal cations, for example Cu, which are known to catalyse the nitrogen-forming reaction. 

To 2 ml. of the ester, add 2--3 drops of a saturated freshly prepared solution of scdium bisulphite. On shaking, a gelatinous precipitate of the bisulphite addition product (D) of the keto form separates, and on standing for 5-10 minutes usually crystallises out. This is a normal reaction of a ketone (see p. 344) hydrogen cyanide adds on similarly to give a cyanhydrin. 

I. Action of sulphuric add. To 0 5 ml. of the alcohol, add 0 5 ml. of cone. H2SO4 and shake the mixture. Heat is evolved and a white gelatinous polymer gradually separates. The reaction is hastened by warming and the product darkens. 

The free radicals initially formed are neutralized by the quinone stabilizers, temporarily delaying the cross-linking reaction between the styrene and the fumarate sites in the polyester polymer. This temporary induction period between catalysis and the change to a semisoHd gelatinous mass is referred to as gelation time and can be controUed precisely between 1—60 min by varying stabilizer and catalyst levels. 

A typical recipe for batch emulsion polymerization is shown in Table 13. A reaction time of 7—8 h at 30°C is requited for 95—98% conversion. A latex is produced with an average particle diameter of 100—150 nm. Other modifying ingredients may be present, eg, other colloidal protective agents such as gelatin or carboxymethylcellulose, initiator activators such as redox types, chelates, plasticizers, stabilizers, and chain-transfer agents. 

Barrier Layers. Depending on composition, barrier layers can function simply as spatial separators or they can provide specified time delays by swelling at controlled rates or undergoing reactions such as hydrolysis or dissolution. Suitable barrier materials include cellulose esters and water-permeable polymers such as gelatin and poly(vinyl alcohol) (see Barrier polymers). 

Copper Hydroxide. Copper(II) hydroxide [20427-59-2] Cu(OH)2, produced by reaction of a copper salt solution and sodium hydroxide, is a blue, gelatinous, voluminous precipitate of limited stabiUty. The thermodynamically unstable copper hydroxide can be kiaetically stabilized by a suitable production method. Usually ammonia or phosphates ate iacorporated iato the hydroxide to produce a color-stable product. The ammonia processed copper hydroxide (16—19) is almost stoichiometric and copper content as high as 64% is not uncommon. The phosphate produced material (20,21) is lower ia copper (57—59%) and has a finer particle size and higher surface area than the ammonia processed hydroxide. Other methods of production generally rely on the formation of an iasoluble copper precursor prior to the formation of the hydroxide (22—26). 

Bone cleaning is the second stage of en2ymatic extraction. The soHd bone fraction from the first separation is mixed 1 1 with hot water (65—75°C) and treated with alkaline-type proteases. After a reaction time of one hour, the bones are separated and washed with water. The cleaned bones make an excellent raw material for the production of gelatin. 

If the ester is dry enough to use in this reaction it will not give a gelatinous mass of sodium hydroxide when treated with a little sodium. 

Inorganic salts of metals work by two mechanisms in water clarification. The positive charge of the metals serves to neutralize the negative charges on the turbidity particles. The metal salts also form insoluble metal hydroxides which are gelatinous and tend to agglomerate the neutralized particles. The most common coagulation reactions are as follows ... 

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