Hydrochloric acid formation irradiation

By using microwave irradiation, a suspension of starch (10%) in dilute hydrochloric acid (0.5 M) is completely hydrolyzed to glucose within 5 min without the formation of colored byproducts. The same suspension of starch heated at 100 ° C in sealed tubes was hydrolyzed to glucose after 60 min, but some retrograded starch still remained suspended in the solution. If the retrograded starch is isolated, resuspended in dilute hydrochloric acid and irradiated, it is completedy hydrolyzed after 5 min.97 In the presence of metal halides, complete hydrolysis was achieved in 2-3 min.98... 

However, further a possibility of the formation of several different reaction products in similar processes was reported [97-99]. With the help of microwave irradiation and ultrasonication, the problem of selectivity was also touched in these communications. It was found that three-component reaction of equimolar mixture of 5-amino-Al-arylpyrazole-4-carboxamides, aldehydes, and cyclic (3-diketones in DMF under conventional thermal heating or under microwave irradiation at 150°C yielded pyrazoloquinazolines 68. The treatment at room temperature under ultrasonication gave the same reaction products, although addition of catalytic amounts of hydrochloric acid changed direction and positional isomeric quinazolines 69 were only isolated in this case. 

Since the Joliot-Curies believed that a similar capture of the alpha-particle, with formation of an isotope of phosphorus, had occurred during the bombardment of the aluminum, they treated a piece of irradiated aluminum with hydrochloric acid. The liberated hydrogen carried with it the new activity, probably in the form of phosphine, leaving the aluminum residue inactive. The nuclear reaction which took place during the bombardment was therefore as follows ... 

Irradiation of compound 357 (R = Me) in methanol and ethanol at 300 nm gave ethyl 2-methyl-4-oxo-4//-pyrimido[2,l-a]isoquinoline-3-car-boxylate (371) and 3-alkoxy-2-methyl 4//-pyrimido[2,l-a]isoquinoline-4-ones (369, R = Me, R1 = Me, Et) along with two imidazo[2,l-a]isoquino-lines (368, R = Me and 372) and a ring-opened product (92AJC1811). At 254 nm the yields of 4//-pyrimido[2,l-a]isoquinolin-4-ones (369, R = Me and 371) and 368, (R = Me) were lower no formation or trace of them was observed in acetonitrile, acetone, acetic acid, and ethyl acetate. Irradition of compound 357 (R = Me) at 300 nm in acetonitrile containing 36% hydrochloric acid afforded 3-chloro-2-methyl-4//-pyrimido[2,l-a]isoquinolin-4-one (373) in 31-81% yields and other products. 

The application of arylpyruvic acids 256 in place of pyruvic acid in three-component reactions leads to dramatic changes in the direction of the process. Refluxing of starting compounds for 3 hours of irradiating with microwave at 170°C for 20 minutes in acetic acid yielded 3-hydroxy-4,5-diaryl-l-azolyl-2,5-dihydro-li/-2-pyrrolones 258 [203] (Scheme 3.73). Under ultrasonic irradiation in ethanol with the addition of catalytic amounts of hydrochloric acid or in acetic acid, the reaction proceeds in a different direction with the formation of pyrimidinecarboxylic acids 259. In the case of pyruvic acid the course of the three-component reaction does not so drastically depend on the activation method or solvent type as well as from temperature mode [202]. 

Padwa and Gehrlein reported139 that excited-state behavior of 1,6-dihydropyridazines differs from that of other diazacyclohexadienes. Thus photooxidation of 2,5,6-triphenyl-1,6-dihydropyridazine (36a) in 95% ethanol gave pyridazinone (83). However, when irradiation of dihydropyridazines (36) was carried out in cyclohexene in the presence of fumaronitrile, a [2 + 2] cycloadduct (84) was obtained. Furthermore, the authors noted that the dihydropyridazine system underwent a deep-seated skeletal rearrangement when treated with aqueous acid. Thus reaction of 36a with aqueous hydrochloric acid results in the formation of 1,3,4-triphenylpyrazole (85) [Eq. (24)]. 

By removing water under a reduced pressure at 40 °C, the ester of 4-vinylphenylboronic acid (0.30 g, 2.0 mmol) and sialic acid (0.62 g, 2.0 mmol) were prepared in dry pyridine (200 mL). The product was directly used for the polymerization (the covalent conjugate did not have to be isolated, since its formation was almost quantitative). This ester, ethylene glycol dimethacrylate (5.6 g, 28.2 mmol) and ADVN were dissolved in DMF (3.2 mL), and the polymerization was initiated by irradiating with UV light at 4 °C. After 12 h, the polymer was ground, and treated with 1 1 mixture of 0.01 M hydrochloric acid and methanol. By this post-treatment, the boronic acid esters were hydrolyzed and the sialic acids were removed from the polymer [2],... 

As for the physical-chemical properties, radiation stability and thermal stability are most important. Irradiation does not appear to pose great problems. Elevated temperatures may cause dehydration processes in the host rock, resulting in large quantities of free water. Rock salt formations are frequently interspersed with camallite (KChMgClj 6H2 0), which will probably be dehydrated when heated above llO C and may even develop hydrochloric acid above 16S°C. In addition it is of low strength and easily soluble in water. 

In a similar study, pentachlorophenol (47 pM) in an air-saturated solution containing titanimn dioxide suspension was irradiated with UV fight ( = 330-370 run). Major chemical intermediates included /r-choranil, tetrachlorohydroquinone, hydrogen peroxide and o-chloranil. The intermediate compoimds were attacked by hydroxyl radicals during the latter stages of irradiation forming HC02, acetate and formate ions, carbon dioxide and hydrochloric acid (Mills and Hoffman, 1993). 

Photolytic. When 2,4,5-T (10 M) in oxygenated water containing titanium dioxide (2 g/L) suspension was irradiated by sunlight ( >340 run), 2,4,5-trichlorophenol, 2,4,5-trichlorophenyl formate and nine chlorinated aromatic hydrocarbons formed as major intermediates. Complete mineralization yielded hydrochloric acid, carbon dioxide and water (Barbeni et al., 1987). 

The dosimeter is based on the formation of hydrochloric acid (HCl) upon irradiation via dissociative electron attachment, since the monochlorobenzene, as a good electron scavenger, reacts both with the dry and the solvated electrons. The HCl is in dissociated form in the solution and its formation is shown in the following reaction scheme ... 

Photolysis of aminopyridines has been studied by Taylor and his co-workers. Ultraviolet irradiation of 2-aminopyridine (and several substituted 2-aminopyridines) in hydrochloric acid solution results in the formation of the 1,4-dimer having the anti-trans configuration IX-SS. 

Experimental studies have shown that irradiation and heating of polyvinyl chloride insulation found on electrical cables in many reactor containment will yield both hydrochloric acid (HCl), sulfiirous acid (H2SO3), and sulfuric acid (H2SO4). Some investigators believe that acids formed by the combination of radiolysis and pyrolysis of electrical cable insulation can be of dominant importance to the pH of solutions in the reactor containment. Others feel that acid formation by this process is over-emphasized because acids generated within the pol5mer are not able to escape to the atmosphere except when they are formed near the polymer surface. 

The appropriately substituted vinylogous amides can imdergo an intramolecular photocycloaddition-retro-Mannich-Mannich sequence. This sequence is analogous to the photocycloaddition-retro-aldol-aldol sequence shown in the formation of 19 from 15 (vide supra). Thus, irradiation of 110 leads to the formation of ketoimine 112, the product of photoaddition followed by rerra-Mannich fragmentation. Reaction of 112 with 1 equiv of trimethyloxonium tetrafluoroborate, followed by treatment of the resulting iminium ketone with aqueous hydrochloric acid, provides the photocycloaddition-re/ro-Mannich-Mannich product 113 in 50% yield from the acyclic photosubstrate 110. ... 

A new synthesis of cycloalkanones was devised and is based upon the photolysis of spiroazirines in alcohol followed by aqueous hydrolysis. Irradiation of spiroazirine 240 in methanol resulted in the quantitative formation of imine 241. Clean conversion to benzaldehyde and the corresponding cycloalkanone 242 was accomplished by treating the photoproduct with a 10% aqueous hydrochloric acid solution. 

The substitution of the hydrogen in the aliphatic side-chain by chlorine occurs in as a radical chain mechanism. In industrial chlorinations the formation of chlorine radicals is achieved either by irradiation (ultraviolet light, beta-radiation), or by the use of elevated temperature (100 - 200 °C). The reactants must be free of dissolved iron salts (build-up of Friedel-Crafts-catalysts), oxygen (radical scavenger), and water (build-up of hydrochloric acid). 

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