Cyanogen reactions

X 10 l.inole. sec at 1.85 and 4.9 torr, respectively. This behavior could not be explained. It was not possible for them to determine unequivocally the nature of the initial reaction between O atoms and cyanogen, reaction (21). Either the sequence... 

Potassium cupro-cyanide is the most convenient form in which cuprous cyanide can be used in Sandmeyer s Reaction. It is prepared by adding an excess of potassium cyanide to copper sulphate solution, whereby the cupric cyanide which is formed immediately breaks down to give cuprous cyanide and cyanogen, and the cuprous cyanide then dissolves in the excess of potassium... 

Removal of maleic and fumaric acids from the cmde malononitrile by fractional distillation is impractical because the boiling points differ only slightly. The impurities are therefore converted into high boiling compounds in a conventional reactor by means of a Diels-Alder reaction with a 1,3-diene. The volatile and nonvolatile by-products are finally removed by two vacuum distillations. The by-products are burned. The yield of malononitrile amounts to 66% based on cyanogen chloride or acetonitrile. 

Treatment of quinoline with cyanogen bromide, the von Braun reaction (17), in methanol with sodium bicarbonate produces a high yield of l-cyano-2-methoxy-l,2-dihydroquinoline [880-95-5] (5) (18). Compound (5) is quantitatively converted to 3-bromoquinoline [5332-24-1], through the intermediate (6) [66438-70-8]. These conversions are accompHshed by sequential treatment with bromine in methanol, sodium carbonate, or concentrated hydrochloric acid in methanol. Similar conditions provide high yields of 3-bromomethylquinoHnes. 

The N-oxides of isoquinolines have proved to be excellent intermediates for the preparation of many compounds. Trialkylboranes give 1-alkyl derivatives (147). With cyanogen bromide in ethanol, ethyl N-(l- and 4-isoquinolyl)carbamates are formed (148). A compHcated but potentially important reaction is the formation of 1-acetonyLisoquinoline and 1-cyanoisoquinoline [1198-30-7] when isoquinoline N-oxide reacts with metbacrylonitrile in the presence of hydroquinone (149). Isoquinoline N-oxide undergoes direct acylamination with /V-benzoylanilinoisoquinoline salts to form 1-/V-benzoylanilinoisoquinoline [53112-20-4] in 55% yield (150). A similar reaction of AJ-sulfinyl- -toluenesulfonamide leads to l-(tos5larriino)isoquinoline [25770-51-8] which is readily hydrolyzed to 1-aminoisoquinoline (151). 

H. A. Hageman, "The Von Braun Cyanogen Bromide Reaction," in R. Adams and co-workers, eds.. Organic Reactions, Vol. 7, John Wiley Sons,... 

Guanidines. Guanidines (10) were one of the first aniline derivatives used as accelerators. They are formed by reaction of two moles of an aromatic amine with one mole of cyanogen chloride. Diphenylguanidine (DPG) has enjoyed a resurgence ia demand as an activator for sulfenamides and a co-accelerator ia tire tread compounds which employ siUca fillers for low rolling resistance. Guanidines alone show too Htde activity to be extensively used as primary accelerators. There were no U.S. producers as of mid-1996. 

The Kixnig reaction (Fig. 5) has been used to determine the amount of nicotinic acid and niacinamide. In this procedure, quatemization of the pyridine nucleus by cyanogen bromide is followed by ring opening to generate the putative dialdehyde intermediate. Reaction of this compound with an appropriate base, such as p-rr ethyl am in oph en o1 sulfate (47) or sulfanilic acid (48), generates a dye. The concentration of this dye is deterrnined c olo rime trie ally. 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

Deall lation. Chloroformates such as vinyl chloroformates (40) are used to dealkylate tertiary amines. Chloroformates are superior to the typical Von Braun reagent, cyanogen bromide, because of increased selectivity producing cleaner products. Other chloroformates such as aHyl, methyl, phenyl, and trichloroethyl have also been used in dealkylation reactions. Although the dealkylation reaction using chloroformates is mostiy carried out on tertiary amines, dealkylation of oxygen or sulfur centers, ie, ethers or thioethers, can also be achieved. a-Chloroethyl chloroformate [50893-53-3] (ACE-Cl) (41,42) is superior to all previously used chloroformates for the dealkylation reaction. ACE-Cl has the advantage that the conditions requked for ACE... 

When the benzenesulfinates were substituted with electron-withdrawing groups, e.g., p-nitro- and p-cyanobenzenesulfinate, the yields were slightly improved when the reaction time with cyanogen chloride was lengthened to 1 hour. 

Whereas sulfonyl halides have been known for a long time and, especially the chlorides, have become of great synthetic value, sulfonyl cyanides were unknown until 1968. They were first prepared by van Leusen and co-workers from the reaction of sulfonylmethylenephos-phoranes with nitrosyl chloride. The same group also investigated part of their chemistry. Since then, two more, completely different, methods of synthesis were published from sulfinates with cyanogen chloride,and by the oxidation of thiocyanates. ... 

Chemical Reactivity - Reactivity with Water No reaction, but water, provides heat to vaporize liquid cyanogen Reactivity with Common Materials No reaction Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

The photolytic and thermolytic decomposition of azides in the presence of olefins has been applied to aziridine synthesis. However, only a limited number of steroid aziridines have been prepared in this manner. The patent literature reports the use of cyanogen azide at ca. 50° for 24 hours in ethyl acetate for the preparation of an A-nor- and a B-norsteroidal aziridine. The addition is believed to proceed via a triazoline. The reaction of cholest-2-ene with ethyl azidoformate takes place in a nonselective manner to produce a mixture of substances, including C—H insertion products. 

C. Reaction of Enamines of 3-Ketones with Cyanogen Azide... 

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

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