Halogen thiocyanates

P. W. Austin. Unsaturated, halogenated thiocyanates, the preparation thereof and use as a biocide. Patent EP 316058,1989. 

While there are several reports concerning electrophilic substitution on to (5,5)-fused heterocycles, very few of these involve a study with the parent system. The ir-excessive systems (50), (51), (52) and (53) were found to be susceptible to attack by electrophilic reagents at the positions indicated, leading to alkylation, formylation (Vilsmeier-Haack reaction), acylation, tritylation, metalation, tricyanoethylation, halogenation, thiocyanation, nitrosation, nitration and diazo coupling (77HC(30)l). 

B. Conformational effects B. Usefulness of the halogens thiocyanate or thiourea... 

CHEMICAL PROPERTIES Combustible incompatible with strong oxidizers, acetates, halogens, thiocyanates and bases reacts with alcohol stable when stored in glass in refrigerator FP (75°C) LFL (2.9%) UFL (not available). 

CHEMICAL PROPERTIES stable when stored in glass containers at 5 C (41 F) can undergo hydrolysis to hydracrylic acid reacts with alcohol incompatible with acetates, halogens, thiocyanates, and thiosulfates FP(74°C, 165°F) LFL/UFL (2.9%, unknown) AT (unknown). 

Dinuclear ort/zo-metallated complexes consist of two ligands joined through a central bridge (Fig. 1). They have been widely studied, and several types of mesogenic, metal complexes derived from azobenzene, benzylideneaniline, benzalazine (imine) and phenylpyrimidine derivatives, with a wide variety of intermetallic bridges, such halogens, thiocyanates, carboxylates, have been reported [8, 9]. 

Incompatibilities and Reactivities Acetates, halogens, thiocyanates, thiosulfates [Note May polymerize upon storage.] ... 

Replacement of halogen, sulfonate, or sulfate substituents with a variety of inorganic anions such as azide, cyanate, halogen, thiocyanate, etc., via PTC is presently a common process for organic synthesis widely used in industry ... 

Control experiment. This is not necessary if the sodium peroxide is known to be chlorine-free. If there is any doubt on this point, the whole operation should be repeated precisely as before, but omitting the organic halogen compound. A small thiocyanate titration value may be found, and this should be deducted from all determinations in which the above quantity of the particular batch of sodium peroxide is used. 

The halogen in the 5-position of 2-aminothiazoles is usually reactive and is used for further reaction (see Chapter V). The reaction may take place in the same medium as thiocyanation (437-440), rhodanation (441). or reaction with NaNO (435). Similarly, a mixture of 2-amino-4-methylthiazole and thiourea in H2O yields 5,5 -thiobis(2-amino-4-methyDthiazole (202) after addition of iodine (Scheme 128) (442). 

A number of compounds of the types RBiY2 or R2BiY, where Y is an anionic group other than halogen, have been prepared by the reaction of a dihalo- or halobismuthine with a lithium, sodium, potassium, ammonium, silver, or lead alkoxide (120,121), amide (122,123), a2ide (124,125), carboxylate (121,126), cyanide (125,127), dithiocarbamate (128,129), mercaptide (130,131), nitrate (108), phenoxide (120), selenocyanate (125), silanolate (132), thiocyanate (125,127), or xanthate (133). Dialkyl- and diaryUialobismuthines can also be readily converted to secondary bismuthides by treatment with an alkali metal (50,105,134) ... 

In an analogous manner, DCPD reacts with alcohols and phenols to form ether derivatives, and with halogen acids, thiocyanic acid, and various carboxyhc acids to form esters. These esters are used as perfume components (67). Dicyclopentadiene alcohol and a number of the ethers, esters, and glycol adducts have been claimed as coal and ore flotation aids (68). 

A thiocyanato group can be introduced by treatment of the corresponding chloro or bromo compounds with ammonium, sodium or potassium thiocyanate. In polychloro compounds only one halogen is replaced. 

Pseudohalides of Se in which the role of halogen is played by cyanide, thiocyanate or selenocyanate are known and, in the case of Se are much more stable with respect to disproportionation than are the halides themselves. Examples are Se(CN)2, Se2(CN)2, Se(SeCN)2, Se(SCN)2, Se2(SCN)2. The selenocyanate ion SeCN is ambidentate like the thiocyanate ion, etc., p. 325), being capable of ligating to metal centres via either N or Se, as in the osmium(IV) complexes [OsCl5(NCSe)], [OsCl5(SeCN)], and trans-[OsCU(NCSe)(SeCN)]2-.920) Tellurium and polonium pseudohalogen analogues include Te(CN)2 and Po(CN)4 but have been much... 

The effect of a substituent may be substantially modified by fast, concurrent, reversible addition of the nucleophile to an electrophilic center in the substituent. Ortho- and para-CS.0 and pam-CN groups have been found by Miller and co-workers to have a much reduced activating effect on the displacement of halogen in 2-nitrohaloben-zenes with methoxide ion [reversible formation of hemiacetal (143) and imido ester anions (144)] than with azide ion (less interaction) or thiocyanate (little, if any, interaction). Formation of 0-acyl derivatives of 0x0 derivatives or of A-oxides, hydrogen bonding to these moieties, and ionization of substituents are other examples of reversible and often relatively complete modifications under reaction conditions. If the interaction is irreversible, such as hydrolysis of a... 

N 24.12% brick red solid mp, decomps when heated over 300°. Insol in w and the usual organic solvents as well as weak acids and alkalies. Comm prepn (Ref 3) is from thiocyanic acid and/or thiocyanates either by anodic oxidation or by interaction with hydrogen peroxide or halogens. The yield is impure because it contains both H and O. The S content varies between 45 and 55%. Lab prepn of the pure polymer is by reacting the Na salt of 5-chlor-3-mercapto 1,2,4-thiodiazols with either acet, ethanol or w (Refs 1 2)... 

Compounds in which the anomeric hydroxy group is replaced by a halogen atom are named as glycosyl halides. Pseudohalides (azides, thiocyanates etc.) are named similarly. 

Tellurium Tetrahydrofuran Tetranitroaniline Tetranitromethane Thiocyanates Thionyl chloride Thiophene Thymol Halogens, metals Tetrahydridoaluminates, KOH, NaOH Reducing materials Aluminum, cotton, aromatic nitro compounds, hydrocarbons, cotton, toluene Chlorates, nitric acid, peroxides Ammonia, dimethylsulfoxide, linseed oil, quinoline, sodium Nitric acid Acetanilide, antipyrine, camphor, chlorohydrate, menthol, quinine sulfate, ure- thene... 

In recent times, the development of new ionic liquids has made great progress. Important developments include a range of new halogen-free ionic liquids (e.g., benzenesulfonates [13], toluenesulfonates, alkylsulfates [14], hydro-gensulfate [15, 16], dicyanamides [17], thiocyanates [18], etc.), as well as functionalized (task-specific) [19-23], fluorinated [24], deuterated [25] and chiral ionic liquids [26-30]. 

This method can naturally only be used when no other acids are formed. In that case the halogen is titrated with thiocyanate by Volhard s method. 

In actual practice, however, such titrations are more or less restricted to those involving precipitation of Ag+ with anions, for instance halogens (Cl , Br, I-) and thiocyanate (SCN-). Generally, it is quite difficult and tedious to locate the exact point at which further addition of reagent affords no more precipitation. Therefore, the choice and wisdom of a chemical reaction is preferably sought so as to result in either a coloured solution or a coloured precipitate at the end point. A typical instance may be cited by application of potassium chromate (K2Cr04) solution in the above case whereby any extra drop of silver nitrate, after all the chloride has been precipitated, immediately causes precipitation of red chromate showing that the end point has been duly achieved. 

Volhard titration analychem Determination of the halogen content of a solution by titration with a standard thiocyanate solution. fol,hart tT tra-shan voltameter See coulometer. val tam-ad-ar ... 

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