The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

Repetto, Sonia L; Costello, James F.; Lam, Joseph K.-W.; Ratcliffe, Norman M.

doi:10.3762/bjoc.12.143

Cited by 7 publications

(13 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It might be possible that an increased ring strain at the nitrogens of the tetrahydroquinazoline system could increase the basicity of these compounds and therefore accelerate the induction of hydrolysis, although previous studies showed that the relationship between the magnitude of ring strain and the resulting nitrogen basicity is not straightforward [53–54]. Probably more interesting, the hydrolysis of cyclic geminal ethers was recently reported to be drastically accelerated by introduction of sterically demanding side groups through reduction of the activation barrier [55]. These results are consistent with the herein reported data supporting a preferred elimination of the aldehyde fragment from the respective tetrahydroquinazoline in compounds with increased ring energy.…”

Section: Resultsmentioning

confidence: 99%

Experimental and theoretical investigations into the stability of cyclic aminals

Sawatzky¹,

Drakopoulos²,

Rölz³

et al. 2016

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

Background: Cyclic aminals are core features of natural products, drug molecules and important synthetic intermediates. Despite their relevance, systematic investigations into their stability towards hydrolysis depending on the pH value are lacking. Results: A set of cyclic aminals was synthesized and their stability quantified by kinetic measurements. Steric and electronic effects were investigated by choosing appropriate groups. Both molecular mechanics (MM) and density functional theory (DFT) based studies were applied to support and explain the results obtained. Rapid decomposition is observed in acidic aqueous media for all cyclic aminals which occurs as a reversible reaction. Electronic effects do not seem relevant with regard to stability, but the magnitude of the conformational energy of the ring system and pK a values of the N-3 nitrogen atom. Conclusion: Cyclic aminals are stable compounds when not exposed to acidic media and their stability is mainly dependent on the conformational energy of the ring system. Therefore, for the preparation and work-up of these valuable synthetic intermediates and natural products, appropriate conditions have to be chosen and for application as drug molecules their sensitivity towards hydrolysis has to be taken into account.

show abstract

Section: Resultsmentioning

confidence: 99%

Experimental and theoretical investigations into the stability of cyclic aminals

Sawatzky¹,

Drakopoulos²,

Rölz³

et al. 2016

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…All the fuel dehydrating agents considered in this study were predicted to partition preferentially into the fuel phase. On the basis of hydrolysis products possessing logK ow less than zero, Although sterically demanding substituents can increase the reaction rate of five-membered ring systems [17], the impact upon the lipophilicity of the hydrolysis products undermines the partitioning properties of the de-icer (i.e., P16). We decided however, to continue to investigate candidate 16 because of the unusually high kinetic activity as water scavenger in the surrogate model (water:acetonitrile=1:4).…”

Section: Fdii Additive Selectionmentioning

confidence: 99%

“…The implications of this finding are that lipophilic ortho esters which preferentially partition into the fuel phase will hydrolyse much more slowly in the presence of dissolved water, whereas a rapid hydrolysis reaction is expected to occur at the interface with free water [14]. Prior work saw the assembly of a library of potential FDII in which the geminal ethers 1-16 ( Figure 1) were ranked according to their rate constants in their reaction with water (i.e., the hydroxonium catalytic coefficient = logk H+ ) in a solvent system that mimics the water/fuel interface (water:acetonitrile = 1:4 v/v) [17]. The rate constants for structures 1-16 (logk H+ ) are presented on the vertical ordinate of Figure 3 and the horizontal ordinate corresponds to logK ow with zero representing the boundary between the H 2 O and fuel surrogate phases.…”

Section: Fdii Additive Selectionmentioning

confidence: 99%

“…Finally, a proof of concept experiment was undertaken to establish whether the additives could thereby illustrating the impact of the inherent acidity of Jet A-1 [14,17]. The reaction was stirred for 2 hours and then analysed by both Karl Fischer titration (industry standard for determining residual water) and GC-FID (to determine product concentration; see Table 2, Figure 7).…”

Section: Proof Of Concept Studymentioning

confidence: 99%

“…We further demonstrated that acyclic ortho esters are effective dehydrating agents under acidic conditions [14]. In a recent study [17], we reported the dehydrating properties of a range of acyclic and cyclic geminal ethers (i.e., 1-16; Figure 1) using a model fuel system, along with the absolute rates for the hydrolysis reactions. Here, we report on the experimentally determined de-icing properties of the hydrolysis products (denoted with the prefix P) of selected cyclic geminal ethers (i.e., P1-16 -see supporting information for structures), and finally describe a proof of concept study which illustrates how the inherent acidity of fuel may catalyse the dehydration reaction of these compounds.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dual Action Additives for Jet A-1: Fuel Dehydrating Icing Inhibitors

et al. 2016

View full text Add to dashboard Cite

A novel approach for protecting jet fuel against the effects of water contamination based upon Fuel Dehydrating Icing Inhibitors (FDII) is presented. This dual-action strategy is predicated on the addition of a fuel-soluble water scavenger that undergoes a kinetically fast hydrolysis reaction with free water to produce a hydrophilic ice inhibitor, thereby further militating against the effects of water crystallization. Criteria for an optimum FDII were identified and then used to screen a range of potential water-scavenging agents, which led to a closer examination of systems based upon exo/endo-cyclic ketals and both endo- and exo-cyclic ortho esters. The ice inhibition properties of the subsequent products of the hydrolysis reaction in Jet A-1 were screened by differential scanning calorimetry. The hydrolysis products of 2-methoxy-2-methyl-1,3-dioxolane demonstrate similar ice inhibition performance to DiEGME over a range of blend levels. The calorific values for the products of hydrolysis were also investigated, and it is clear that there would be a significant fuel saving on use of the additive over current fuel system icing inhibitors. Finally, three promising candidates, 2-methoxy-2-methyl-1,3-dioxolane, 2-methoxy-2-methyl-1,3-dioxane, and 2-methoxy-2,4,5-trimethyl-1,3-dioxolane, were shown to effectively dehydrate Jet A-1 at room temperature over a 2 h period.

show abstract

Separation, recovery and upgrading of 2,3‐butanediol from fermentation broth

Rajale

Yang

Judge

et al. 2023

Biofuels Bioprod Bioref

View full text Add to dashboard Cite

2,3-Butanediol (BDO) is a bio-derived building block available from biomass through biochemical methods in high titers (>120 g L −1 ) making it an attractive target for production and further upgrading to chemical products and fuels such as sustainable aviation fuel. A key challenge to enable the adoption of BDO as a precursor is the effective separation and isolation of this molecule from the fermentation broth. 2,3-Butanediol has a boiling point higher than that of water (177°C), and as a consequence, separation via distillation methods is an energy-intensive and therefore costly approach. We have improved the BDO separation through conversion to a 1,3-dioxolane directly in fermentation broth via reaction with bio-derived aldehydes catalyzed by a solid acid catalyst. The resulting dioxolane phase separates from the fermentation broth, allowing for easy decantation and isolation in >90% isolated yield. Isolated dioxolane can be used directly as a compression iginition fuel, trans-acetalized to recover high-purity BDO or used directly in a catalytic process as a BDO synthon to produce methyl ethyl ketone with aldehyde recovery in near quantitative yield.

show abstract

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

Cited by 7 publications

References 51 publications

Experimental and theoretical investigations into the stability of cyclic aminals

Experimental and theoretical investigations into the stability of cyclic aminals

Dual Action Additives for Jet A-1: Fuel Dehydrating Icing Inhibitors

Separation, recovery and upgrading of 2,3‐butanediol from fermentation broth

Contact Info

Product

Resources

About