Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions.

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, ) in hydroxylic solvents. The rate constants of the solvolysis of were well correlated using the Grunwald-Winstein equation in all of the 20 solvents (R = 0.985).

The Influence of a Terminal Chlorine Substituent on the Kinetics and the Mechanism of the Solvolyses of -Alkyl Chloroformates in Hydroxylic Solvents.

A previous study of the effect of a 2-chloro substituent on the rates and the mechanisms of the solvolysis of ethyl chloroformate is extended to the effect of a 3-chloro substituent on the previously studied solvolysis of propyl chloroformate and to the effect of a 4-chloro substituent on the here reported rates of solvolysis of butyl chloroformate. In each comparison, the influence of the chloro substituent is shown to be nicely consistent with the proposal, largely based on the application of the extended Grunwald-Winstein equation, of an addition-elimination mechanism for solvolysis in the solvents of only modest solvent ionizing power, which changes over to an ionization mechanism for solvents of relatively high ionizing power and low nucleophilicity, such as aqueous fluoroalcohols with an appreciable fluoroalcohol content.

The Effect of the Nitro Group in the Solvolysis of Benzyl and Benzoyl Halides.

A kinetic study was carried out on the solvolysis of -nitrobenzyl bromide (-isomer, ) and -nitrobenzyl bromide (-isomer, ), and -nitrobenzoyl chloride (-isomer, ) in a wide range of solvents under various temperatures. In all of the solvents without aqueous fluoroalcohol, the reactions of were solvolyzed at a similar rate to those observed for , and the reaction rates of were about ten times slower than those of the previously studied -nitrobenzoyl chloride (-isomer, ). For solvolysis in aqueous fluoroalcohol, the reactivity of was kinetically more reactive than .

Correlation of the rates of solvolysis of -butyl chlorothioformate and observations concerning the reaction mechanism.

The "parent" tertiary alkyl chloroformate, -butyl chloroformate, is unstable, but the -butyl chlorothioformate () is of increased stability and a kinetic investigation of the solvolyses is presented. Analyses in terms of the simple and extended Grunwald-Winstein equations are carried out. The original one-term equation satisfactorily correlates the data with a sensitivity towards changes in solvent ionizing power of 0.

Correlation of the rates of solvolysis of i-butyl fluoroformate and a consideration of leaving-group effects.

The specific rates of solvolysis of isobutyl fluoroformate (1) have been measured at 40.0 °C in 22 pure and binary solvents. These results correlated well with the extended Grunwald-Winstein (G-W) equation, which incorporated the N(T) solvent nucleophilicity scale and the Y(Cl) solvent ionizing power scale.

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters.

The specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous organic mixtures with wide ranging nucleophilicity and ionizing power.

Corrrelation of the specific rates of solvolysis of ethyl fluoroformate using the extended Grunwald-Winstein equation.

The specific rates of solvolysis of ethyl fluoroformate have been measured at 24.2 degrees C in 21 pure and binary solvents. These give a satisfactory correlation over the full range of solvents when the extended Grunwald-Winstein equation is applied.

Grunwald-Winstein analysis: isopropyl chloroformate solvolysis revisited.

Specific rates of solvolysis at 25 degrees C for isopropyl chloroformate (1) in 24 solvents of widely varying nucleophilicity and ionizing power, plus literature values for studies in water and formic acid, are reported. Previously published solvolytic rate constants at 40.0 degrees C are supplemented with two additional values in the highly ionizing fluoroalcohols.

Fast and sensitive trace analysis of malachite green using a surface-enhanced Raman microfluidic sensor.

A rapid and highly sensitive trace analysis technique for determining malachite green (MG) in a polydimethylsiloxane (PDMS) microfluidic sensor was investigated using surface-enhanced Raman spectroscopy (SERS). A zigzag-shaped PDMS microfluidic channel was fabricated for efficient mixing between MG analytes and aggregated silver colloids. Under the optimal condition of flow velocity, MG molecules were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower zigzag-shaped PDMS channel.

Rate and product studies in the solvolyses of N,N-dimethylsulfamoyl and 2-propanesulfonyl chlorides.

Contrary to earlier suggestions of an S(N)1 pathway for solvolyses of N,N-dimethylsulfamoyl chloride (1), an extended Grunwald-Winstein equation treatment of the specific rates of solvolysis in 32 solvents shows an appreciable sensitivity towards changes in both solvent nucleophilicity and solvent ionizing power. The actual values are very similar to those obtained in earlier studies of the solvolyses of sulfonyl and phosphoryl chlorides, solvolyses which are believed to proceed by an S(N)2 pathway. The observation of similar selectivities in aqueous-alcohol solvents further supports this assignment.

A kinetic study of the solvolyses of methyl and ethyl chloroglyoxalates.

[reaction: see text] Solvolyses of methyl and ethyl chloroglyoxylates proceed about 10(6) times faster than the identical solvolyses of the corresponding chloroformates. The correlation parameters obtained from application of the extended Grunwald-Winstein equation are consistent with an addition-elimination (association-dissociation) mechanism over the full range of solvents, with the addition step being rate determining.

Ultra-sensitive trace analysis of cyanide water pollutant in a PDMS microfluidic channel using surface-enhanced Raman spectroscopy.

Rapid and highly sensitive trace analysis of cyanide water pollutant in an alligator teeth-shaped PDMS microfluidic channel was investigated using surface-enhanced Raman spectroscopy. Compared with previously reported analytical methods, the detection sensitivity was enhanced by several orders of magnitude.

Solvolysis-decomposition of 2-adamantyl chloroformate: evidence for two reaction pathways.

Reaction of 2-adamantyl chloroformate under a variety of solvolytic conditions leads to 2-adamantyl chloride accompanied by solvolysis products, some with and some without retention of the CO(2) unit. For example, in 100% ethanol, only 4.8% 2-adamantyl chloride is formed with the mixed carbonate (88%) being the dominant product, and in 100% 2,2,2-trifluoroethanol, the products are both formed with loss of CO(2), 59% of the chloride and 41% of the ether.

Rate and product studies with benzyl and p-nitrobenzyl chloroformates under solvolytic conditions.

The specific rates of solvolysis of p-nitrobenzyl chloroformate are well correlated using the extended Grunwald-Winstein equation, with a high sensitivity (l) to changes in solvent nucleophilicity (N(T)) and a moderate sensitivity (m) to changes in solvent ionizing power (Y(Cl)). The values are consistent with a rate-determining association within an association-dissociation pathway. The selectivity values (S) for the attack at the acyl carbon show a modest preference for ethanol over water and a relatively high preference for ethanol over 2,2,2-trifluoroethanol (TFE).