Preparative Procedures

Timberlake, Joseph W.; Stowell, J. C.

doi:10.1002/0470023414.ch4

Cited by 9 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Addition to the nitrogen lone pairs should give rise to N -sulfide products. The corresponding N -oxides, e.g., the N -oxides derived from DABCO and azoalkanes (see above), can be isolated, , such that there is little reason to doubt that the corresponding N -sulfides do not possess a certain thermodynamic stability as well. However, due to the much weaker N−S bond strength with reference to the N−O bond, it seems quite likely that the N -sulfides decompose by bimolecular reaction (eq 13), or rearrange by insertion into the relatively weak C−H (for the amines) or N−H (for the hydrazines) bonds (eq 15).…”

Section: Discussionmentioning

confidence: 99%

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution

1997

View full text Add to dashboard Cite

The 248-nm laser flash photolysis of methyl isothiocyanate (MeNCS) was used to generate S( 3 P J ) ground state atoms in acetonitrile solution. The reaction of S( 3 P J ) atoms with the MeNCS precursor produces molecular diatomic sulfur S 2 ( 3 Σ g -) in its ground state, which possesses an absorption at ca. 270 nm. The first-order growth of this absorption was used to monitor the decay kinetics of the sulfur ( 3 P J ) atoms and to measure the rate constants for their reactions with additives. The rate constants obtained for a number of olefins, e.g., 9.7 × 10 7 M -1 s -1 for ethyl vinyl ether, hydrogen donors, e.g., 3.1 × 10 9 M -1 s -1 for tributyltin hydride, sulfur atom donors, e.g., 5.0 × 10 7 M -1 s -1 for carbon disulfide, and nucleophiles, e.g., 1.3 × 10 9 M -1 s -1 for chloride ions, demonstrate that S( 3 P J ) atoms behave as reactive, yet very selective, intermediates in solution; the highest reactivity was observed toward nitrogen and phosphorus nucleophiles, e.g., 1.2 and 2.1 × 10 10 M -1 s -1 for hydrazine and triethyl phosphite. The comparison with known nucleophilicity constants, e.g., for methyl iodide as electrophile, suggests further that S( 3 P J ) atoms act as potent but relatively soft electrophiles. The reaction modes between S( 3 P J ) atoms and the additives are assumed to involve abstractions of single atoms or addition to double bonds or lone electron pairs. The reaction rate constants for atomic sulfur S( 3 P J ) in solution are compared with previous gas phase data for S( 3 P J ) atoms and with the data for oxygen ( 3 P J ) atoms in solution.

show abstract

Section: Discussionmentioning

confidence: 99%

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution

1997

View full text Add to dashboard Cite

show abstract

“…Herein we report thermolysis kinetics and product studies of two azoalkanes, prepared by a new method, that decompose to captodative − trimethylsilyl (TMS) cyanohydrin radicals. Because of limitations in the synthetic approaches to azoalkanes, − only a single report has appeared previously on their use to generate captodative radicals. Our product studies were carried out with thiophenol as hydrogen donor and with the persistent radical TEMPO to scavenge the initially formed radicals and thus prevent secondary reactions …”

mentioning

confidence: 99%

Thermolysis of Acylazo O-Trimethylsilyl Cyanohydrins: Azoalkanes Yielding Captodatively Substituted Radicals

et al. 1998

View full text Add to dashboard Cite

A new synthetic method has been developed for preparing azoalkanes bearing geminal α-cyano and α-trimethylsiloxy groups. While the symmetrical compound 5 decomposes near room temperature to afford, almost entirely, the C−C dimers, the unsymmetrical azoalkane 3 requires heating to 75 °C. The thermolysis activation parameters of 3 and 5 can be rationalized on steric grounds without invoking captodative radical stabilization. A 13C NMR product study of photolyzed 3 in the presence of TEMPO at 21 °C shows that the fate of caged [tert-butyl, 1-trimethylsiloxy-1-cyanoethyl (14)] radical pairs is disproportionation, 17%, cage recombination, 20%, and cage escape, 63%.

show abstract

Synthese und Zerfall eines Thiadiaziridin‐1,1‐dioxids

Quast

Kees

1977

Chem. Ber.

View full text Add to dashboard Cite

Aus einem uberblick iiber Schwefel enthaltende Systeme, die prinzipiell in einer Dreiringstruktur vorliegen konnen, geht hervor, daD neben den Thiiran-Derivaten nur die 1,l-Dioxide von Thiaziridinen und Thiadiaziridinen stabiler sein sollten als ihre ringoffenen Isomeren. Das Thiadiaziridin-1,l-dioxid 6d entsteht aus dem Kaliumsalz des N,N'-Diadamantylsulfamids 5d mit tert-Butylhypochlorit in hoher Ausbeute. In trockenen, aprotischen Losungsmitteln ist 6d bei 80°C langere Zeit bestandig. Feuchtigkeit lost den Zerfall in SO2 und Diazen 7d aus. In Kohlenwasserstoffen bei 170°C wird hauptsachlich die N-N-Bindung zu einem Diradikal gespalten, das vom Solvens Wasserstoff abstrahiert und in das Sulfamid 5d iibergeht. In Mesitylen und pDiisopropylbenzo1 wurden Dimere der aus dem Solvens entstehenden Radikale isoliert. Der elektronenstohduzierte Zerfall zeigt gewisse Parallelen zum Thermolyseverlauf; dabei tritt jedoch vorwiegend die charakteristische Spaltung der Adamantylgruppen ein.Synthesis and Decomposition of a Tbiadiaziridine 1,l-Dicmide') A survey of sulfur containing systems which in principle may exist as three-membered rings reveals that besides the thiirane derivatives only the 1,l-dioxides of thiaziridines and of thiadiaziridines can be expected to be more stable than their ring-opened isomers. The thiadiaziridine 1,l-dioxide 6d is formed in high yield from the potassium salt of N,N'-diadamantylsulfamide Sd and tert-butyl hypochlorite. In dry aprotic solvents, 6d resists prolonged heating to 80°C. Moisture gives rise to decomposition into SO2 and the diazene 7d. In hydrocarbon solvents at 170°C predominantly a diradical is formed by cleavage of the N-N bond. The diradical abstracts hydrogen from the solvent to afford thesulfamide Sd. In mesitylene and p-diisopropylbenzene, respectively, dimers of the solvent-derived radicals have been isolated. The electron impact induced decomposition parallels the thermolysis to a certain extent. However, the typical cleavage of the adamantyl groups prevails.

show abstract

Preparative Procedures

Cited by 9 publications

References 0 publications

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution

Thermolysis of Acylazo O-Trimethylsilyl Cyanohydrins: Azoalkanes Yielding Captodatively Substituted Radicals

Synthese und Zerfall eines Thiadiaziridin‐1,1‐dioxids

Contact Info

Product

Resources

About

Preparative Procedures

Cited by 9 publications

References 0 publications

Absolute Rate Constants for the Reactions of Sulfur (3PJ) Atoms in Solution

Absolute Rate Constants for the Reactions of Sulfur (3PJ) Atoms in Solution

Thermolysis of Acylazo O-Trimethylsilyl Cyanohydrins: Azoalkanes Yielding Captodatively Substituted Radicals

Synthese und Zerfall eines Thiadiaziridin‐1,1‐dioxids

Contact Info

Product

Resources

About

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution

Absolute Rate Constants for the Reactions of Sulfur (³P_J) Atoms in Solution