Hydrogen cyanide producers

Two synthesis processes account for most of the hydrogen cyanide produced. The dominant commercial process for direct production of hydrogen cyanide is based on classic technology (23—32) involving the reaction of ammonia, methane (natural gas), and air over a platinum catalyst it is called the Andmssow process. The second process involves the reaction of ammonia and methane and is called the BlausAure-Methan-Ammoniak (BMA) process (30,33—35) it was developed by Degussa in Germany. Hydrogen cyanide is also obtained as a by-product in the manufacture of acrylonitrile (qv) by the ammoxidation of propjiene (Sohio process). 

Figure 2.5 Treating an aldehyde with ammonia and hydrogen cyanide produces an df-ammo nitrile. By hydrolysis of the nitrile group an df-amino acid is produced. This synthesis is called the Strecker synthesis.

Enander, Sundwall, and Sorbo - -- 7 found that either oral or Intramuscular administration of 11 to rats at 500 or 100 mg/kg, respectively, increased by many times the urinary excretion of thiocyanate. From the amount of thlocynanate excreted above the base line, the quantity of hydrogen cyanide produced in metabolism of the oxime was calculated to be 0.1 mg/kg—a little more than one-third the LD50 for rats by lntraperitoneal injection. Urine from rats given 120 ymol of II intramuscularly or 400 pmol by mouth contained 3.9-7.8% N-methylpyridinlum-2-nltrlle methanesulfonate. When this compound was injected Intramuscularly into rats at 90 mg/kg, thiocyanate was excreted in the urine in Increased amounts. Also present in the urine was a metabolic product that yielded cyanide on acidification of the urine, similar to a cyanide-yielding metabolite of II found earlier. 

IV. Vapor Pressure Method. —If the free weak acid or weak base is appreciably volatile, it is possible to determine its concentration or, more correctly, its activity, from vapor pressure measurements. In practice the actual vapor pressure is not measured, but the volatility of the substance in the hydrolyzed salt solution is compared with that in a series of solutions of known concentration. In the case of an alkali cyanide, for example, the free hydrogen cyanide produced by hydrolysis is appreciably volatile. A current of air is passed at a definite rate through the alkali cyanide solution and at exactly the same rate through a hydrogen cyanide solution the free acid vaporizing with the air in each case is then absorbed in a suitable reagent and the amounts are compared. The concentration of the hydrogen cyanide solution is altered until one is found that vaporizes at the same rate as does the alkali cyanide solution. It may be assumed that the concentrations, or really activities, of the free acid are the same in both solutions. The concentration of free acid cha in the solution of the hydrolyzed salt of the weak acid may be put equal to cx (cf. p. 374) and hence x and kh can be calculated. 

In papers dedicated to side reactions to nitration, no attention has been paid to the formation of ammonia in the course of the reaction. It is formed from hydrogen cyanide produced by drastic decomposition of nitro compounds. This was discussed in detail in Vol. I, pp. 76—77. The mechanism of the formation of HCN from C-nitro compounds also explains the fact that these nitro compounds yield ammonia in Kjeldahl analysis, where the substance is subjected to the action of oleum at high temperature. 

Two more complicated ring-contraction reactions, both yielding 4-amino-3-oxothiadiazoline 1,1-dioxides, are known. Disselnkoetter reported (71GEP1961864) that the reaction of 1,4,3,5-oxathiadiazine 127 with hydrogen cyanide produced imino derivatives 128, which were easily hydrolyzed to the corresponding oxo derivatives 89b by acid treatment (Scheme 49). The course of the reaction may involve addition of cyanide ion, decarboxylation of the resulting carbamic acid, and a nucleophilic attack at the carbonitrile group, as shown in Scheme 49. 

VIII) which yielded, on treatment with sodium in ether, 1,2-anhydro-DL-glyceritol (glycidol XVI). Reaction of the latter with hydrogen cyanide produced 2-deoxy-DL-ffZi/cero-tetrononitrile (IX). Hydrolysis of the nitrile (IX) with barium hydroxide afforded the desired saccharinic acid (lab). 

Johnson GE, Decker WA, Eomey AJ, Eield JH (1968) Hydrogen cyanide produced from coal and ammonia, bid Eng Chem Process Des Dev 7 137-143... 

Green chemistry methods that help to reduce the total amount of cyanide and/or hydrogen cyanide produced, used, stored, and transported will concomitantly reduce vulnerability to terrorist attacks targeting the chemical sector. What follows are descriptions of some cases, where products or chemicals that conventionally require HCN in their synthesis have successfully reduced or replaced that reliance on HCN in favor of less hazardous alternatives. 

For preparative purposes, Ritter s original procedure of generating the carbonium ion from the alcohol (or olefin) and sulphuric acid is preferred under these conditions, hydrogen cyanide, produced in situ from sodium cyanide, can replace the nitrileSecondary and tertiary alcohols can be used" , and the reaction, providing essentially for substitution by the 5 1 mechanism, is a valuable addition to the methods already discussed. It must be borne in mind, however, that under certain conditions carbonium ion rearrangement is possible, and has indeed been observed in some applications of this reaction... 

The volatile hydrogen cyanide produced under these circumstances may be detected by the color reaction described on page 348 using copper ethyl-acetoacetate and tetrabase. 

In retrospect, if one examines this reaction a little more closely, this unusual synthetic process appears almost inevitable. Indeed, the empirical formula of adenine, HjCsNg, corresponds to that of pentameric hydrogen cyanide, that is to say, that the overall reaction can be represented simply as five molecules of hydrogen cyanide producing one molecule of adenine ... 

Several technical processes have been developed in which reagents presence of a catalyst add to the triple bond. For example, the catalyzed addition of hydrogen chloride gives chloroethene (vinyl chloride), and addition of hydrogen cyanide produces propenenitrile (acrylonitrile). 

Reduction of hydrogen cyanide produces predominantly MMA. The chemistry is described in DBF 1,019,313 and others. This technology is not economically attractive except for backward integration to more elementary raw materials using HCN as an intermediate. 

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