Chloroformic Acid Research Articles

Vibrational and Rovibrational Spectroscopic Data for the Ground and First-Excited States of Phosgene (COCl2), Formic Acid (HCOOH), and Chloroformic Acid (ClCOOH).

While "black box" quantum chemical computations for the determination of rovibronic spectral data are not quite at hand, the present work utilizes the titular molecules to showcase how excited-state quantum chemical methods can be conjoined to quartic force field (QFF) anharmonic rovibrational treatments to provide novel and useful predictions for such data. This work employs hybrid QFFs with explicitly correlated coupled cluster theory along with the equation-of-motion formalism to generate harmonic force constants and time-dependent density functional theory (TD-DFT) to produce anharmonic force constants for the generation of electronically excited-state rovibrational spectral data, in effect, rovibronic spectral data. Specific spectroscopic results from this work show that the fundamental C═O stretch in phosgene as well as in cis- and trans-formic acid drop from the region of around 1800 cm-1 to close to 1100 cm-1 or less in the first excited states of each molecule. While such is expected for these n → π* excitations, this work provides quantitative predictions for these fundamental vibrational frequencies. The most notable theoretical result is that the TD-DFT-based QFFs can experience unexpected failures, and their inclusion in excited-state hybrid QFFs should require at least two functionals to be employed. The computation of DFT QFFs is relatively fast, and such a "doubling up" of the QFFs will not greatly increase the computational time.

On the fate of protonated chloroformates in the gas phase: a competition between forming HCl and chloroformic acid.

Chloroformates are prevalent in the atmosphere due to their utilization as fuel additives and industrial solvents. These species may undergo interactions with atmospheric water resulting in protonated chloroformates. This study delves into the gas-phase dissociation of these protonated species. Tandem mass spectrometry was employed to scrutinize the unimolecular dissociation of protonated methyl (1), ethyl (2), neopentyl (3), and phenyl chloroformate (4). Notably, 1 and 4 exhibited HCl loss, yielding CH3OCO+ and C6H5OCO+, respectively, with 1 additionally generating neutral methanol and ClCO+. 4 additionally loses CO and CO2. In contrast, 2 and 3 each only exhibit a single fragmentation channel, with 2 losing C2H4 to generate protonated chloroformic acid and 3 generating protonated 2-methylbutene by losing neutral chloroformic acid. Density functional theory at the B3LYP/6-311+G(d,p) level of theory was employed to explore minimum energy reaction pathways for each ion, and CBS-QB3 single-point energy calculations were added to provide reliable energetics. The Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of the rate constants for selected competing processes were carried out to link theory and experiment. One common unimolecular process observed was the 1,3-H shift of the proton from the carbonyl oxygen to the ester oxygen before dissociation.

Reaction of diphenylphosphinal formic acid hydrazide with isothiocyanates

A new method was proposed for the preparation of diphenylphosphinylformic acid hydrazide based on the reaction of phosphine oxide and trimethylchlorosilane in the presence of a tertiary amine, followed by interaction with chloroformic acid ester and then hydrazine hydrate. The hydrazide moiety was modified into a thiosemicarbazide moiety by reacting diphenylphosphinylformic acid hydrazide with organic isothiocyanates. It was found that in an aqueous alkaline medium, thiosemicarbazides do not heterocyclize to 1,2,4-triazole-3-thiones, as expected. As a result of the rupture of the P-C bond, diphenylphosphinic acid and a 5-thioxo-1,2,4-triazolidin-3-one were formed.

Synthesis of S-(5-aryl-1,3,4-oxadiazol-2-yl) O-alkyl carbonothioate and alkyl 2-((5-aryl-1,3,4-oxadiazol-2-yl)thio) acetate, and their antimicrobial properties

The S-(5-aryl-1,3,4-oxadiazol-2-yl) O-alkyl carbonothioate (4-9) and the alkyl 2-((5-aryl-1,3,4-oxadiazol-2-yl)thio) acetate (10-15) were synthesized by interaction of 5-aryl-1,3,4-oxadiazole-2-thiones with alkyl esters of chloroformic acid and chloroacetic acid. The yields of target compounds (7-9) obtained with isobutyl chloroformate were 69-73%, compounds (4-6) with propyl chloroformate - 74-79% and compounds (10-15) with alkyl esters of chloroacetic acid - 86-92%, respectively. The structures of the synthesized compounds were confirmed by IR, UV, 1H and 13C NMR spectra. The antibacterial and antifungal activities of these compounds were investigated. The results of in vitro antimicrobial activity tests showed that S-(5-phenyl(2-chlorophenyl)-1,3,4-oxadiazol-2-yl) O-propyl carbonothioate (4-5) and S-(5-phenyl(2-chlorophenyl)-1,3,4-oxadiazol-2-yl) O-isobutyl carbonothioate (7-8) exhibited weak, but selective antibacterial activity against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus). At the same time, no activity was shown by compounds with two chlorine atoms in the aromatic ring (13-15) and alkyl 2-((5-aryl-1,3,4-oxadiazol-2-yl) thio) acetate (10-15).

Phytochemical Screening, Antioxidant and Antimicrobial Activities of Erodium glaucophyllum (L.) L'Hérit

This study deals with the phytochemical analyses, antioxidant and antimicrobial activities screening of Erodium glaucophyllum root bark. Organic extracts (Chloroformic Acid and Ethyl acetate) were screened for their biochemical composition as well as antioxidant and antibacterial activities. Phytochemical screening of Erodium glaucophyllum root bark showed the presence of flavonoids, coumarins, saponins, tannins, antracenosides, phenolics compounds and mucilage. Biochemical screening of the two organic extracts show a highest total polyphenolic content of the two solvent (78.022 ± 0.28 mg GAE/g DM in Chloroform extract and 95.468 ± 0.078 mg GAE/g methyl acetate extract). These values were recorded in the proportion of 70% MeOH. The antioxidant activity was evaluated using DPPH tests, chelation, and the total antioxidant capacity. The antibacterial activity was evaluated by the diffusion test agar vis-a-vis of six bacterial strains. The results show that the levels of polyphenolic content influenced these activities.

ChemInform Abstract: Exploitation of the Ugi—Joullie Reaction in the Synthesis of Libraries of Drug‐Like Bicyclic Hydantoins.

AbstractBicyclic hydantoins are efficiently obtained utilizing a three‐component Ugi—Joullie reaction/cyclization sequence as key complexicity‐generation process using trifluoroacetic acid as synthetic equivalent for chloroformic acid.

Synthesis and structure characterization of soluble starch ethyl carbonates

Starch ethyl carbonates were synthesized applying novel paths including chlorocarbonic acid ethyl ester and ethyl 1H-imidazole-1-carboxylate as reagent. The influence of starch, reaction medium, and base on the degree of substitution (DS) was investigated. The conversion of starch with chlorocarbonic acid ethyl ester in N,N-dimethyl formamide (DMF)/LiCl leads to a preferred substitution of position 6 of the anhydroglucose unit (AGU), on one hand. On the other, the reaction of starch with 1H-imidazole-1-carboxylate in dimethyl sulfoxide (DMSO) or DMF/LiCl results in a preferred functionalization of position 2. The products obtained were well soluble in polar aprotic solvents and in water depending on starch and DS. Intermolecular cross-linking or intramolecular cyclic carbonate formation could not be observed. A detailed structure characterization was carried out by one- and two-dimensional NMR spectroscopy.

Theoretical study on the mechanism of the gas-phase elimination kinetics of alkyl chloroformates

ABSTRACTThe theoretical calculations on the mechanism of the homogeneous and unimolecular gas-phase elimination kinetics of alkyl chloroformates– ethyl chloroformate (ECF), isopropyl chloroformate (ICF), and sec-butyl chloroformate (SCF) – have been carried out by using CBS-QB3 level of theory and density functional theory (DFT) functionals CAM-B3LYP, M06, MPW1PW91, and PBE1PBE with the basis sets 6-311++G(d,p) and 6-311++G(2d,2p). The chlorofomate compounds with alkyl ester Cβ–H bond undergo thermal decomposition producing the corresponding olefin, HCl and CO2. These homogeneous eliminations are proposed to undergo two different types of mechanisms: a concerted process, or via the formation of an unstable intermediate chloroformic acid (ClCOOH), which rapidly decomposes to HCl and CO2 gas. Since both elimination mechanisms may occur through a six-membered cyclic transition state structure, it is difficult to elucidate experimentally which is the most reasonable reaction mechanism. Theoretical calculations show that the stepwise mechanism with the formation of the unstable intermediate chloroformic acid from ECF, ICF, and SCF is favoured over one-step elimination. Reasonable agreements were found between theoretical and experimental values at the CAM-B3LYP/6-311++G(d,p) level.

Exploitation of the Ugi–Joullié Reaction in the Synthesis of Libraries of Drug-Like Bicyclic Hydantoins

A general and efficient method for the synthesis of drug-like fused bicyclic hydantoins is reported. An Ugi–Joullié reaction/cyclisation sequence was exploited as the key complexity-generating process in which trifluoroacetic acid was employed as synthetic equivalent for chloroformic acid. Exemplar diversification of the bicyclic scaffolds was performed to enable subsequent translation to the synthesis of large small molecule libraries, leading to the production of >1000 compounds for addition to the screening collection of the European Lead Factory.

Novel Biologically Active 1,3,2-Oxazaphosphinane Derivatives

The facile synthetic approaches to a wide range of potentially biologically active compounds bearing the cyclic 1,3,2-oxazaphosphinane moiety as a “cell transport” and the residues of formic, acetic, and amino acids or 3,5-bis(benzylidene)piperidone framework have been developed. The methods are based on the Arbuzov reaction of preformed cyclic P(III) esters with chloroacetic or chloroformic acid esters, where the nature of the reactants influences the ratio of cyclic and linear products, cyclizations of susbstituted dichlorophosphoryl compounds with aminopropanols, or amination of P-isothiocyanates.

ChemInform Abstract: A Facile Synthesis of 2,4-Oxazolidinediones.

2,4-Oxazolidinediones bearing 1-aryl-2-methylpropen-1-yl substituent at 3-position were obtained easily by the reaction of 2-chloro-N-(1-aryl-2-methyl-1-propenyl)acetamides with both chloroformic acid ester and potassium carbonate in DMF

ChemInform Abstract: Synthesis of 1,3-Di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles.

Abstract Two protocols have been developed for the synthesis of 1,3-di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles starting from the corresponding N,O-diacyl derivatives obtained by treatment of 2-oxindoles with chloroformic acid esters and triethylamine. The first is rearrangement of N,O-diacylated compounds in the presence of 4-dimethylaminopyridine to give N,C(3)-diacylated products with identical acyl groups in the two positions. The second involves O-deacylation of the N,O-diacylated compounds, followed by O-acylation and rearrangement resulting N,C(3)-diacylated 2-oxindoles with different acyl groups in the two positions.

The Electronic Spectrum of Chloroformic Acid in Comparison to Formic Acid

The electronic spectra of chloroformic acid ClCOOH and formic acid HCOOH are computed in large-scale multireference configuration interaction (MRD-CI) calculations. The computed spectrum of formic acid is in reasonable agreement with prior calculations and experimental data. The first electronic transition of ClCOOH is computed at 6.41 eV (193.4 nm), about 0.5 eV higher than in HCOOH. Together with five strong transitions calculated at 7.66 eV (161.9 nm; 2(1)A' <-- X(1)A'), 8.36 eV (148.3 nm; 3(1)A' <-- X(1)A'), 8.49 eV (146.0 nm; 4(1)A' <-- X(1)A'), 9.00 eV (137.8 nm; 5(1)A' <-- X(1)A'), and 9.44 eV (131.3 nm; 7(1)A' <-- X(1)A'), this can serve as a guideline for experimental search of ClCOOH.

Complete NMR Elucidation of Two N-Protected Trishomocubane Hydantoins and the Ethyl Ester of the Corresponding Amino Acid

In an attempt to resolve a racemic mixture of a trishomocubane hydantoin, the synthesis of a pair of novel diastereomers was obtained by protecting the racemic hydantoin with chlorocarbonic acid-(−)(R)-sec-butyl ester. An achiral i-propyl ester was first used to establish the procedure. The NMR elucidation of both the chiral and achiral N-protected hydantoins is described. Some proton and carbon NMR shifts on the cage are reversed when relative small changes on the protection group are introduced. The chiral centre on the protective group induced splitting of some carbon signals in the 13C spectrum on the cage skeleton, but effective separation of the diastereomers could not be obtained. In a further attempt to demonstrate the potential use of the trishomocubane amino acid in peptide synthesis, the ethyl ester of the cage amino acid was synthesised. The structures of the amino acid derivatives were elucidated with 2D NMR techniques and the assignment of the NMR data is presented.

Efficient Synthesis in Three Steps and Spectral Determination of Methyl‐5‐[(o‐, m‐, and p‐substituted)‐phenylthio]‐2‐benzimidazolecarbamates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient synthesis in three steps and spectral determination of methyl‐5‐[(o‐, m‐, and p‐substituted‐phenylthio]‐2‐benzimidazolecarbamates

AbstractThe preparation and spectral properties often novel methyl 5‐[(o‐, m‐, and p‐substituted)‐phenylthio]‐2‐benzimidazolecarbamates with possible pharmacological activity as antihelmintics is described; by condensation and cyclization between 5‐methylthioures sulfate chloroformic acid methyl ester and 3,4‐diaminophenyl‐substituted‐phenylthio ether dissolved in ethanol. The structures of all final products were corroborated by ir; 1H‐nmr, 13C‐nmr and ms.

Factors contributing to roquefortine yield variability during cultivation of penicillium roquefortii

Variability in the roquefortine yield was shown to be associated with its consumption by the mycelium during isolation of the end product, which depended on temperature, time of culture liquid storage, and biomass concentration. This was also related to the presence in chloroform of chlorocarbonic acid ethyl ester that reacted with roquefortine.

Characterization of Alkoxycarbonyl Radicals by Step-Scan Time-Resolved Infrared Spectroscopy

A series of alkoxycarbonyl radicals has been generated by laser flash photolysis (355 nm) of fluorenone oxime alkyl oxalates in carbon tetrachloride and characterized by time-resolved infrared spectroscopy using the step-scan technique. The alkoxycarbonyl radicals (C=O = 1802 cm−1 for R = ethyl) generally have a lifetime of several microseconds, decaying by reaction with the solvent to yield esters of chloroformic acid. In some cases, decarboxylation yielding alkyl radicals has also been observed. Thus, photolysis of fluorenone oxime tert-butyl oxalate results in the formation of tert-butoxycarbonyl radicals, which subsequently decay, mainly yielding CO2 and tert-butyl radicals. The benzyloxycarbonyl radical and the acetoneiminoxycarbonyl radical both decarboxylate too rapidly to be detected with our spectrometer (25 ns rise-time). Upon purging the solution with oxygen, the alkoxycarbonyl radicals were efficiently quenched, to yield alkoxycarbonylperoxy radicals (C=O = 1845 cm−1 for R = ethyl), which again had a lifetime of the order of several microseconds. A short-lived transient ( = 1768 cm−1, τ ≈ 200 ns) is assigned as the carbonyloxy radical 4a on the basis of comparison with time-resolved UV/Vis data. A further product of the photolysis of fluorenone oxime oxalates can be tentatively assigned as the 9-fluorenylideneiminoxy radical 3 ( = 1670 cm−1), which according to our DFT calculations should show a very intense C=N−O,as. = 1665 cm−1. Fluorenone oxime oxalates are compounds well suited as precursors for alkoxycarbonyl radicals, since they are easily synthesized as crystalline solids, show a convenient absorption at λ = 355 nm, and exhibit a high degree of thermal stability.

Synthesis of 1,3-Di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles

Two protocols have been developed for the synthesis of 1,3-di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles starting from the corresponding N, O-diacyl derivatives obtained by treatment of 2-oxindoles with chloroformic acid esters and triethylamine. The first is rearrangement of N, O-diacylated compounds in the presence of 4-dimethylaminopyridine to give N, C(3)-diacylated products with identical acyl groups in the two positions. The second involves O-deacylation of the N, O-diacylated compounds, followed by O-acylation and rearrangement resulting N, C(3)-diacylated 2-oxindoles with different acyl groups in the two positions.

The gas-phase acidities of substituted carbonic acids

Ab initio molecular orbital methods at the CBS-Q level of theory have been used to study the structure, gas-phase acidities and vibrational spectra of carbonic acid, H 2CO 3, and several of its derivatives RCO 2H (R=F, Cl, NH 2, H and CH 3). Geometry optimizations were performed at the MP2(FC)/6-31G(†) level of theory. The syn forms always are more stable than the anti. The highest gas-phase acidity (1288.5 kJ mol −1) has been calculated for chloroformic acid. Carbonic acid is, according to calculated ionizations of the first hydrogen, about 24 kJ mol −1 more acidic than formic acid. The fundamental vibrational frequencies have been computed using the Becke3LYP/6-311+G(d,p) method. The computed vibrational frequencies for formic and acetic acids were on average 2% higher than the observed values.