Hydrogen chloride, discovery

If nitration under acidic conditions could only be used for the nitration of the weakest of amine bases its use for the synthesis of secondary nitramines would be severely limited. An important discovery by Wright and co-workers " found that the nitrations of the more basic amines are strongly catalyzed by chloride ion. This is explained by the fact that chloride ion, in the form of anhydrous zinc chloride, the hydrochloride salt of the amine, or dissolved gaseous hydrogen chloride, is a source of electropositive chlorine under the oxidizing conditions of nitration and this can react with the free amine to form an intermediate chloramine. The corresponding chloramines are readily nitrated with the loss of electropositive chlorine and the formation of the secondary nitramine in a catalytic cycle (Equations 5.2, 5.3 and 5.4). The mechanism of this reaction is proposed to involve chlorine acetate as the source of electropositive chlorine but other species may play a role. The success of the reaction appears to be due to the chloramines being weaker bases than the parent amines. 

Considerations of mechanism despite their difficulties are extremely valuable and productive. The discovery of the catalytic properties of hydrogen fluoride for condensation reactions came about from considering the mechanisms of certain organic reactions coupled with a knowledge of the chemical and physical properties of hydrogen fluoride. That fundamental acidity is involved in the catalytic properties of hydrogen fluoride is confirmed by the fact that hydrogen chloride under appropriate conditions can catalyze some of the same reactions (Simons and Hart, 81). 

Chlorosulphonic Acid, C1.S02.0H.—-In 1854 the discovery of chlorosulphonic acid by Williamson, by the interaction of hydrogen chloride and sulphur trioxide, was of especial interest. Ideas of valency were immature and undeveloped, and for the systematisation of the knowledge of organic and inorganic compounds reference was made to... 

The problem of cocatalysis in Friedel-Crafts reactions in general and in cationic polymerizations in particular is still unresolved. In 1936 Ipatieff and Grosse (30) made the significant observation that pure ethylene and aluminum chloride will not polymerize except in the presence of added water or hydrogen chloride. This can be regarded as the discovery of cocatalysis. Ten years later British scientists started a systematic investigation in this area and proposed the concept of cocatalysis which is now generally accepted (31—34). Early development was excellently surveyed (35) and will not be discussed here. 

Further confirmation resulted from the discovery that the phosphoribose condenses with methyl alcohol in the presence of dry hydrogen chloride to give a furanoside only. Also, on reduction of the phosphoribose, an optically active phosphoribitol is formed, showing that the phosphoryi group is not at position (3). 

Since Hartmann s 1904 discovery, astronomers have learned that a variety of elements and compounds exist in the interstellar medium, alheit at very low concentrations. In fact, Hartmann s original discovery was based on his observation of the spectrum of calcium in the ISM. Today, astrochemists know of at least 123 interstellar molecules. The chart on page 24 lists some of the more common of these molecules. Notice that some familiar elements and compounds have heen identified in the ISM, including ozone (03), hydrogen chloride... 

Shortly after the discovery of hydrogen chloride and hydrogen fluoride in the Venusian atmosphere in 1967, chemists begin to investigate possible atmospheric/surface interactions that would buffer (control) the amount of both gases in the atmosphere. One of the hypothesized reactions involves the interaction of HCl with the mineral nepheline (NaAlSiOJ, as follows ... 

The free chlorine acts as a catalyst and a single chlorine atom may break down tens of thousands of ozone molecules before it returns to the troposphere. In the troposphere, chlorine reacts with hydrogen and forms hydrogen chloride that is rained out. Since ozone absorbs biologically-damaging UV radiation before it reaches the earth s surface, its depletion increases the risks associated with UV exposure. Ultraviolet radiation and over-exposure are linked with skin cancers, cataracts, and suppression of immune system response. In 1985, this problem started to attract everyone s attention by the dramatic announcement of the discovery of a hole in the ozone layer over... 

Cumene gained particular technical importance following the discovery of the phenol synthesis via the oxidation of cumene by Heinrich Hock and Shon Lang in Clausthal/Germany in 1944. Cumene had already been obtained by Cornelius Radziewanowski in 1895, by reaction of benzene and isopropyl chloride in the presence of aluminum filings and dry hydrogen chloride. A 66 % yield was... 

They subsequently performed a reaction of 1-chloropentane with aluminum chloride using benzene as the solvent. Once again, they observed evolution of hydrogen chloride, but this time they found that 1-pentylbenzene ( amylbenzene ) was a major product In describing their discovery to the Chemical Society of France in 1877, they reported, With a mixture of [alkyl] chloride and hydrocarbon [an arene], the formation is established, in good yield, of hydrocarbons from the residues of the hydrocarbon less H and from the chloride less Cl. It is thus that ethylbenzene, amylbenzene, benzophenone, etc., are obtained. A general representation of the transformation is shown in the following equation. 

Simple (halomediyl)boronic esters are not accessible by methods used for higher homologs. The discovery that (chloromethyl)lithium can be generated at -78 C from chloroiodomethane by treatment widi butyllithium in the presence of triisopropyl borate and captured immediately to form the (chloromethyl)borate salt and, after acidification, the boronic ester has provided practical access to these useful reagents [33]. The less expensive reagent dibromomethane under similar conditions generates (bromomethyl)lithium and yields (bromomethyl)(triisopropyl)borate anion (42), which is converted into diisopropyl (bromomethyl)boronate (43) by treatment with anhydrous hydrogen chloride or, more conveniently, methanesulfonic acid while the reaction mixture is still cold (Scheme 8.8) [34]. 

Details polychloroprene was Invented by DuPont scientists on April 17,1930 after Dr. Elmer K. Bolton of DuPont laboratories attended a lecture by Fr. Julius Arthur NIeuwland, a professor of chemistry at the University of Notre Dame. Fr. Nieuwland s research was focused on acetylene chemistry and during the course of his work he produced divinyl acetylene, a jelly that firms Into an elastic compound similar to rubber when passed over sulfur dichlorlde. After DuPont purchased the patent rights from the university, V fellace Carothers of DuPont took over commercial development of Nieuwland s discovery in collaboration with NIeuwland himself. DuPont focused on monovinyl acetylene and reacted the substance with hydrogen chloride gas, manu cturing chloroprene. ... 

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