Hydrogen cyanide, ionization

In the second step the hydrogen cyanide ionizes to form H+ and cyanide ion. The proton is transferred to ammonia,... 

Chemical Properties. Hydrogen cyanide is a weak acid its ionization constant is of the same magnitude as that of the natural amino acids (qv). Its stmcture is that of a linear, triply bonded molecule, HC=N. 

Absorption. Absorption of cyanide across the gastrointestinal mucosa depends on the pH of the gut and the pKa and lipid solubility of the particular cyanide compound. Hydrogen cyanide is a weak acid with a pKa of 9.2 at 25 °C. The acidic environment in the stomach favors the non-ionized form of hydrogen cyanide and facilitates absorption. Information regarding the rapid lethal effects following oral intake of cyanide in humans (Gosselin et al. 1976) indicates that cyanide is rapidly absorbed from the gastrointestinal tract. 

Burgers, P.C. Holmes, J.E. Mommers, A.A. Terlouw, J.K. Neutral Products of Ion Fragmentations Hydrogen Cyanide and Hydrogen Isocyanide (HNC) Identified by Collisionally Induced Dissociative Ionization. Chem. Phys. Lett. 1983,102,1-3. 

Two examples of chemical ionization (isobutane) spectra. The top spectrum is that of a pure compound. The bottom spectrum is that of a mixture of two compounds with masses 261 and 270. They correspond respectively to the loss of hydrogen cyanide and water. 

Studies of proton transfers from carbon with f1/2 less than one microsecond are quite rare. The ionization of hydrogen cyanide in aqueous alkaline solution has been studied [20] using the ultrasonic stationary method which is applicable to reactions with tl/2 in the range 10 5 to 10 9 sec. Several reactions of benzyl carbanion having f 1/2 in the range 10-6—5 x 10-8 sec have been studied in tetrahydrofuran. The carbanion was generated by pulse radiolysis of solutions of dibenzyl mercury and its subsequent reaction with water and alcohols was followed spectrophotometrically [21]. 

Enthalpies and entropies of ionization of water and hydrogen cyanide, Aust. J. Chem., 49, (1996), 651-657. Cited on page 435. 

Step 1 The negatively charged carbon of cyanide ion is nucleophilic and bonds to the carbonyl carbon of the aldehyde or ketone. Hydrogen cyanide itself is not very nucleophilic and does not ionize to form cyanide ion to a significant extent. Thus, a source of cyanide ion such as NaCN or KCN is used. 

With the development of the definitions of acids and bases due to Bronsted and Lowry many solvents were found to which these definitions could be applied. It followed, therefore, that solvents were classified as proton containing solvents and proton-free solvents ". The former contain hydrogen in an ionizable form and the cations produced by auto-ionization are considered to be solvated protons. Typical proton-containing solvents are water, liquid ammonia, hydrazine, hydrogen cyanide, sulphuric acid, nitric acid, acetic and formic acids, alcohols and amides. Liquid hydrogen fluoride and the other hydrogen halides may also be included in this group of solvents. 

This instrument is a handheld CWA monitoring device using an advanced form of IMS that does not require a radioactive source for ionization. The unit is equipped with an algorithm for detection of hydrogen cyanide, phosgene, and chlorine, in addition to conventional nerve and blister agents. 

Write an equation for the ionization of hydrogen cyanide, HCN, in aqueous solution. What is the equilibrium expression Ka for this acid ionization ... 

Mercuric cyanide, which ionizes in solution only to a minute degree, remains unaltered if its solution is treated with dilute nitric, sulfuric, phosphoric or oxalic acid even after prolonged heating. In contrast, dilute hydrochloric acid leads to the inunediate release of hydrogen cyanide. The same holds true when alkali halides are added to a solution of mercuric cyanide that has been acidified with sulfuric acid etc. Hence the underl3ung reaction, with participation of halogen ions, may be ... 

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