Carbonyl selenide

An isocyanate intermediate may also be involved in the selenium-catalyzed process, which starts with the formation of carbonyl selenide from the reaction between selenium and CO, followed by nucleophilic attack by NuH (Scheme 28). When NuH = primary amine, the resulting RNH(CO)SeH intermediate may eliminate H2Se to give the isocyanate, which then reacts with Nu H to give the final product (Scheme 28, path a). Alternatively, oxidation of Nu(CO)SeH by 02 may lead to a bis(carbamoyl)diselenide species, which is attacked by NuH (Scheme 28, path b). 

The facile sulfur selenium exchange from carbonyl selenide to carbonyl sulfide is noteworthy [184], ... 

Carbon diselenide CSe2 Carbonyl selenide COSe. Hydrogen selenide HjSe... 

Until recently, no selenium monohalide could be isolated only the short-lived radicals SeF, SeCl, and SeBr were identified in the gas phase. SeF, can be produced by reaction of fluorine atoms (by passing CF4 through a microwave discharge) with carbonyl selenide in a flow system. It has been detected by ESR spectroscopy and the Se-F bond length (1.742 A) is close to the value reported for SeF2 (1.69 A), deduced from infrared spectra. ... 

The primary product is aniline (eq. (8)), which then undergoes addition of carbonyl selenide, Se=C=0, in the presence of a strong base [17]. The resulting urethane can further be converted into the methylene diurethane, which is then cracked to the diisocyanate MDI 2, a key industrial intermediate for the production of polyurethane foams and elastomers (cf. Section 3.3.5). It was probably for toxicity reasons that completion of a technical plant at one of the Arco sites [18] was hampered. 

The reaction between aluminium(III) selenide and phosgene at 219 C represents a good synthetic route to carbonyl selenide [774] ... 

A possible reaction path is shown in Scheme 15.43 [116]. Selenium reacts with carbon monoxide in the presence of bases to generate carbonyl selenide (SeCO) as an active carbonylating species. Carbonyl selenide can be isolated by treatment of amine salts of selenolcarboxylic acids with sulfuric acid [117]. Nucleophilic attack at the carbon of SeCO leads to the formation of selenolcarboxylic acid derivatives, fhe pathways from which to give the desired carbonylation products involve several possibihties, depending on the nature of nucleophiles, i.e. ... 

CarbophUic Addition of Organocopper Reagents to Carbonyl Selenide (SeCO) 119... 

Carbonyl sulfide (SCO) reacts with Grignard reagents at the carbonyl carbon [87], and this has been used to introduce a thiocarboxyl unit into organic molecules. For example, thiocarboxylations of enolates [88], phosphorous ylides [89], and an acyllithium [90] have been reported. Selenocarboxylation to organocopper reagents with carbonyl selenide (SeCO), followed by alkylation, gave selenol esters (Eq. 42) [91]. 

Recently, the spectroscopic identification of carbonyl teUuride, obtained by photolysis of H2Te in CO or 1 % CO/Ar matrices at 10 K, was reported. Carbonyl selenide is readily synthesized in situ from R2NC(0)Se R2NH2+ and acids, but little of its chemistry is known. Poly(carbon diselenide) is obtained as a black powder by thermal polymerization or photopolymerization of carbon diselenide. The obtained polymer is highly disordered, and it has a head-to-head polymer structure". 

Carbonyl selenide Carbonyl sulfide Carboxin S,5-dioxide Af-(Carboxymethyl)-Af-methylglydne 8-Carboxyquinoline 2-Carboxythiophene l-Carboxy-W,W,7 f-trimethylmethana-minium, inner salt Carbromal Carbutamide Carbyloxime Carfimate Carmustine Carnegine... 

Two further examples of the usefulness of the R-line diagram in the estimation of Na or Xa values in difficult systems are afforded by the following papers. Pearson and Robinson (1932) found a molecular weight of 103.0 for carbonyl selenide (bp —22.9°C) from the gas density at 0 C, whereas its actual molecular weight is 107.2. The discrepancy was attributed to the presence of either carbon monoxide or carbon dioxide, which were stated to be appreciably soluble in the liquid. Under the conditions stated, Xccb would not be more than 0.05, and xco not more than 0.01, The solubility pattern of COSe itself can be approximately assessed by reference to Fig. 140. The R-line values for COSe at 0°C may be assessed at Ncose = 0-41, cose = 0.7 for 1 atm, based on the vapor-pressure data. 

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