On the Reaction of Dithioarsonites, L‐As(SPh)₂ (L = Ar, R), with Octasulfur in the Presence of Triethylamine as an Activator. The Crystal Structure of the Sesquisulfide (2‐O₂N‐C₆H₄‐As)₂S₃

Abstract

Octasulfur (elemental sulfur) does not react at room temperature with a variety of As III compounds of the type Ar-As(SPh) 2 and R-As(SPh) 2 . However, in the presence of catalytic amounts of triethylamine, which probably acts as an activator of octasulfur, reactions do take place. The products isolated from the aromatic dithioarsonites are not the expected Ar-As(S)(SPh) 2 but the sulfide, cyclo-(PhAsS) 4 , and the sesquisulfides, (ArAs) 2 S 3 , which are the same with those obtained by reduction of arylarsonic acids with hydrogen sulfide. The action of S 8 /Et 3 N on aliphatic dithioarsonites did not give any As V products but gave mixtures of non-separable Inhaltsübersicht. S 8 (elementarer Schwefel) reagiert bei Raumtemperatur nicht mit einer Reihe von As III -Verbindungen des Typs Ar-As(SPh) 2 und R-As(SPh) 2 . Jedoch erfolgen Reaktionen in Gegenwart von katalytischen Mengen von Triethylamin, die wahrscheinlich als Aktivator des S 8 wirken. Die isolierten Produkte aus der Reaktion der aromatischen Dithioarsenite sind aber nicht das erwartete Ar-As(S)(SPh) 2 sondern die Sulfide cyclo-(PhAsS) 4 und die Sesquisulfide, (ArAs) 2 S 3 , die denen gleichen, die bei der Reduktion von Arylarsenitsäuren mit Schwefelwasserstoff erhalten werden.

The reactions of triethylamine-activated octasulfur with thioarsinites, L2As‒SPh (L = Me, Ph), Bunsen's cacodyl disulfide, Me2As(S)‒S‒AsMe2, and triphenylarsine

“…The reaction of 1a with 1/8S 8 under a 2:2 stoichiometry is expected to give 3a (equilibrated with 4a [25]), Equation (2). After 30 h reaction, S 8 was detected by TLC.…”

“…LÀ ÀAs(SPh) 2 (L ¼ Ar, R) do not react under mild conditions with octasulfur probably because they cannot open the octasulfur ring [2]. However, in the presence of triethylamine, ArÀ ÀAs(SPh) 2 and S 8 gave cyclo-(PhAsS) 4 and the sesquisulfides (PhAs) 2 S 3 , (2-O 2 NÀ ÀC 6 H 4 À ÀAs) 2 S 3 , whereas the aliphatic RÀ ÀAs(SPh) 2 gave a non-separable mixture of oligomeric (RAsS) x [2].…”

“…LÀ ÀAs(SPh) 2 (L ¼ Ar, R) do not react under mild conditions with octasulfur probably because they cannot open the octasulfur ring [2]. However, in the presence of triethylamine, ArÀ ÀAs(SPh) 2 and S 8 gave cyclo-(PhAsS) 4 and the sesquisulfides (PhAs) 2 S 3 , (2-O 2 NÀ ÀC 6 H 4 À ÀAs) 2 S 3 , whereas the aliphatic RÀ ÀAs(SPh) 2 gave a non-separable mixture of oligomeric (RAsS) x [2]. The sesquisulfide (PhAs) 2 S 3 was oxidized by S 8 /NaHS, a system which obviously opens the octasulfur ring [8(a)], to the sodium salt of phenylarsonotrithioic acid, PhÀ ÀAsS 3 Na 2 [9].…”

“…Continuing our work on the use of triethylamine-activated octasulfur for the oxidation of As(III) compounds under mild conditions [2,3,5,7], in this article, we report on the reactions of Me 2 AsÀ ÀSPh 1, and Ph 2 AsÀ ÀSPh 1a, with S 8 in the absence and in the presence of catalytic amounts of triethylamine (as an activator of S 8 [6]) in stoichiometries which satisfy the Equations (1)-(3), as well as using excess S 8 or triethylamine, to see whether we can prepare the As(V) compounds 2/2a, 3/3a, and 5/ 5a.…”

“…In particular, compounds of As(III) having no alkyl or aryl group directly bonded to arsenic behave differently toward S 8 depending on the nature of the compound. Thus, octasulfur oxidized alkaline arsenite, Na 3 AsO 3 , to the trisodium salt of monothioarsenic acid, Na 3 AsO 3 S [1], by a mechanism most probably involving the attack of AsO 3 37 on the penultimate sulfur of À ÀSÀ ÀS 5 À ÀSÀ ÀSÀ ÀAsO 3 27 [2]. Triaryl trithioarsenites, (ArS) 3 As, on the other hand, do not react with S 8 in solution or in the molten state [3] contrary to the earlier reports [4].…”