Generalized Synthesis and Physical Properties of Dialkoxy Disulfides

Abstract

A substrate study was undertaken in order to probe the scope of S(2)Cl(2) coupling of alcohols to form dialkoxy disulfides. Compounds 1b and 1f are new; along with 1a, 1c, 1h, and 1j, all of the title compounds are fully characterized, and the yields of 1a and 1c have been optimized from previously reported syntheses. The effect of the R-substituent about the OSSO moiety has been carefully probed as yields vary. A substrate and a solvent study of the coalescence behavior of this class was carried out. The origin of the inherently large barrier to rotation and the resultant thermal decomposition pathway is discussed. Both phenomena are shown to be solvent independent; hindered rotation is substrate independent. The decomposition of 1a is ca. 7 kcal/mol higher than the barrier to rotation about the S-S bond. The combined evidence suggests acyclic unsymmetric homolytic cleavage of the dialkoxy disulfide.

Chemical shift and coupling constant analysis of dibenzyloxy disulfides

“…1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded on a Varian instrument with tetramethylsilane (TMS) as an internal standard. Chemical shifts (δ) are given in ppm, coupling constants (J) in Hz, and spin multiplicities as s (singlet), d (doublet), ABq (AB quartet) and m (multiplet).…”

“…Dialkoxy disulfides were first synthesized in the late 19 th century by Lengfeld [1], however they lay in relative obscurity until the 1990's when Harpp and others began to examine this novel structural moiety [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Although examples of the isomeric form, thionosulfite (-OS(=S)O-) have been reported, however only in cyclic structures [3,12], the predominate form is believed to be the linear arrangement, (-OSSO-).…”

“…This has been attributed to the conjugation of a lone pair on a sulfur atom with theσ* orbital of the adjacent -O-S-bond [13]. It has been postulated that this provides double bond character and a decrease in bond length of the -S-S-bond to 1.95 Å [2] from a typical 2.05Å [19][20][21] for simple disulfides.…”

NiO/MgO/SiO2 supported cobalt(II) tetrasulfophthalocyanine as an efficient, selective, and recyclable catalyst for the aerobic oxidation of thiols to disulfides

“…Selective oxidation of thiols to the corresponding symmetric disulfides is an important reaction in biological and chemical processes [1][2][3][4][5]. A number of procedures for this conversion include treatment with reagents such as cerium(IV) salts [6], transition metal oxides [7], sodium chlorite [8], nitric oxide [9], sodium perborate [10], H 2 O 2 [11], KMnO 4 / CuSO 4 [12] and I 2 /CeCl 3 Á7H 2 O [13].…”

Mild and highly efficient transformation of thiols to symmetrical disulfides using urea–hydrogen peroxide catalyzed by a Mn(III)–salen complex

“…Disulfides are of interest compounds in organic synthesis [1][2][3][4][5][6] and play significant roles in biological [7] and chemical processes [8][9]. Being readily available form commercial suppliers and easily synthesized, thiols serve as the most frequently employed precursors to disulfides.…”