Photoionization studies of internally reactive small clusters: van der Waals complexes of 1,3-butadiene with sulfur dioxide

Grover, J. R.; Walters, E. A.; Newman, Jennifer F.; White, Michael G.

doi:10.1021/ja00174a008

Cited by 11 publications

(5 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alternatively, since butadiene is known to form a van der Waals complex with SO 2 with a binding energy of 3.24 ± 0.48 kcal/mol we cannot exclude mechanism (b) …”

mentioning

confidence: 99%

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

et al. 1998

View full text Add to dashboard Cite

“…Alternatively, since butadiene is known to form a van der Waals complex with SO 2 with a binding energy of 3.24 ± 0.48 kcal/mol we cannot exclude mechanism (b) …”

mentioning

confidence: 99%

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

et al. 1998

View full text Add to dashboard Cite

“…An experimental stabilization energy of −3.24 ± 0.48 kcal/mol was estimated for the s-trans complex in a photoionization study by Grover et al . Comparison between the binding energies calculated above suggests that 1 •SO 2 complexes are, in general, more stable than butadiene•SO 2 complexes.…”

Section: Calculations and Discussionmentioning

confidence: 90%

“…The calculated binding energies obtained for the complexes of s-trans and s-cis butadiene at the same levels of theory are -3.2 (s-trans)/-0.6 (scis) kcal/mol [MP2/6-31G(d,p)] and -1.9 (s-trans)/+1.3 (scis) kcal/mol [B3LYP/6-31G(d,p)], respectively. An experimental stabilization energy of -3.24 ( 0.48 kcal/mol was estimated for the s-trans complex in a photoionization study by Grover et al 24 Comparison between the binding energies calculated above suggests that 1•SO 2 complexes are, in general, more stable than butadiene•SO 2 complexes.…”

Section: Calculations and Discussionmentioning

confidence: 93%

See 1 more Smart Citation

Ab Initio and Experimental Studies on the Hetero-Diels−Alder and Cheletropic Additions of Sulfur Dioxide to (E)-1-Methoxybutadiene: A Mechanism Involving Three Molecules of SO₂

et al. 2002

View full text Add to dashboard Cite

Kinetics on the cheletropic addition of sulfur dioxide to (E)-1-methoxybutadiene (1) to give the corresponding sulfolene 2 (2-methoxy-2,5-dihydrothiophene-1,1-dioxide) gave the rate law d[2]/dt = k[1][SO(2)](x)() with x = 2.6 +/- 0.2 at 198 K. Under these conditions, no sultine 3 [(2RS,6RS)-6-methoxy-3,6-dihydro-1,2-oxathiin-2-oxide] resulting from a hetero-Diels-Alder addition was observed, and the cheletropic elimination 2 --> 1 + SO(2) did not occur. Ab initio and DFT quantum calculations confirmed that the cheletropic addition 1 + SO(2) --> 2 follows two parallel mechanisms, one involving two molecules of SO(2) and the transition structure with DeltaG(++) = 18.2 +/- 0.2 kcal/mol at 198 K (exptl); 22.5-22.7 kcal/mol [B3LYP/6-31G(d,p)], the other one involving three molecules of SO(2) with DeltaG(++) = 18.9 +/- 0.1 kcal/mol at 198 K (exptl); 19.7 kcal/mol [B3LYP/6-31G(d,p)]. The mechanism involving only one molecule of SO(2) in the transition structure requires a higher activation energy, DeltaG(++) = 25.2 kcal/mol [B3LYP/6-31G(d,p)]. Comparison of the geometries and energetics of the structures involved into the 1 + SO(2) --> 2, 3 and 1 + 2SO(2) --> 2, 3 + SO(2) reactions obtained by ab initio and DFT methods suggest that the latter calculation techniques can be used to study the cycloadditions of sulfur dioxide. The calculations predict that the hetero-Diels-Alder addition 1 + SO(2) --> 3 also prefers a mechanism in which three molecules of SO(2) are involved in the cycloaddition transition structure. At 198 K and in SO(2) solutions, the entropy cost (TDeltaS(++)) is overcompensated by the specific solvation by SO(2) in the transition structures of both the cheletropic and hetero-Diels-Alder reactions of (E)-1-methoxybutadiene with SO(2).

show abstract

“…To support the excited state dynamics suggested by the TD‐DFT PECs, we investigated the SO 2 ‐expulsion by direct irradiation using femtosecond TRPES, which was previously used to investigate the dynamics of pericyclic reactions [24,46] . As sulfolene has a different ionization potential (10.1 eV) [47] from the products SO 2 (12.34 eV) [48] and butadiene (9.07 eV), [49] we should be able to easily distinguish photoelectrons from these different species.…”

Section: Resultsmentioning

confidence: 99%

The Sulfolene Protecting Group: Observation of a Direct Photoinitiated Cheletropic Ring Opening

et al. 2021

View full text Add to dashboard Cite

Photolabile protecting groups offer synthetic routes with facile deprotection by photolysis, providing higher yields with less workup. Protecting groups producing only gaseous byproducts upon removal are particularly desirable as sustainable reagents. Cheletropic reactions provide just this combination of photocleavable groups with gaseous byproducts. However, only few protecting groups for cheletropic reactions have been described and little is known about their photochemistry and associated stereochemistry. Here we show that the sulfolene protecting group, used for diene protection and functionalization, can be photochemically removed. First, using TD‐DFT, we conclude that the photochemical ring‐opening occurs conrotatorily in a concerted process, consistent with the Woodward‐Hoffmann rules. Experimentally, we demonstrate that this process can be photoinitiated by radiation between 180 and 300 nm and confirm the proposed stereochemistry in solution. Using time‐resolved photoelectron spectroscopy, we determine that the first steps in the photochemical ring‐opening of sulfolene occur on ultrafast timescales (≤84 fs), consistent with a fully concerted process. Our findings expand applications of the sulfolene protecting group and promise an easy strategy for control of cis‐trans isomerization.

show abstract

Photoionization studies of internally reactive small clusters: van der Waals complexes of 1,3-butadiene with sulfur dioxide

Cited by 11 publications

References 2 publications

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

Ab Initio and Experimental Studies on the Hetero-Diels−Alder and Cheletropic Additions of Sulfur Dioxide to (E)-1-Methoxybutadiene: A Mechanism Involving Three Molecules of SO₂

The Sulfolene Protecting Group: Observation of a Direct Photoinitiated Cheletropic Ring Opening

Contact Info

Product

Resources

About

Photoionization studies of internally reactive small clusters: van der Waals complexes of 1,3-butadiene with sulfur dioxide

Cited by 11 publications

References 2 publications

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

Sulfur Dioxide Promotes Its Hetero-Diels−Alder and Cheletropic Additions to 1,2-Dimethylidenecyclohexane

Ab Initio and Experimental Studies on the Hetero-Diels−Alder and Cheletropic Additions of Sulfur Dioxide to (E)-1-Methoxybutadiene: A Mechanism Involving Three Molecules of SO2

The Sulfolene Protecting Group: Observation of a Direct Photoinitiated Cheletropic Ring Opening

Contact Info

Product

Resources

About

Ab Initio and Experimental Studies on the Hetero-Diels−Alder and Cheletropic Additions of Sulfur Dioxide to (E)-1-Methoxybutadiene: A Mechanism Involving Three Molecules of SO₂