Alkali Hydrolysis Research Articles

Stability-indicating LC Method for Quantification of Azelnidipine: Synthesis and Characterization of Oxidative Degradation Product

In the work presented here, the degradation behavior of azelnidipine under diverse forced degradation conditions was studied. A stability-indicating liquid chromatographic method was established which could separate and resolve azelnidipine from its degradation products. Further, chemical kinetics under acidic and alkaline conditions were studied, and validation studies were performed. Using reversed-phase chromatography, azelnidipine and its formed degradants were resolved using phosphate buffer (pH 3.0) and methanol in a mixture of 10:90% v/v as a mobile phase at a flow rate of 1.0 mL/min. All eluents were detected at a wavelength of 256 nm. Azelnidipine was degraded under acid, alkali, wet heat, and oxidized environment. The pH-dependent rate of hydrolysis of azelnidipine was studied under acidic and alkaline conditions and chemical kinetics were determined. Further, the oxidative degradation product of azelnidipine was synthesized and characterized as 3-(1-benzhydrylazetidin-3-yl) 5-isopropyl 2-amino-6-methyl-4-(3-nitrophenyl) pyridine-3,5-dicarboxylate (dehydro-AZD). The susceptibility of azelnidipine to hydrolysis was attributed to the presence of ester at 3 and 5 positions of 1,4 dihydropyridine. Further, under oxidative conditions, the aromatization of 1,4 dihydropyrinine resulted in dehydro-AZD. Azelnidipine followed the first-order reaction under acid and alkali hydrolysis, and was more susceptible to degradation under acidic conditions. The synthesized and confirmed dehydro-AZD was found as one of the metabolites and impurities of azelnidipine. The evaluated validation parameters ascertained the practicality of the method for the quantification of azelnidipine tablets.

Industrial Gelatin from Leather Chrome Shavings Wastes

A step towards minimizing the environmental pollution of leather tanning , leather chrome shavings wastes were treated with Li2CO3 to extract technical or industrial gelatin as an added value material. Isolation and characterization of gelatin obtained from chrome-tanned shavings were done. The alkali hydrolysis products obtained, showed good physical and chemical properties in terms of gel strength, swelling and thermal stability. The optimum hydrolysis conditions using Li2CO3 were found to be 5 hr. extraction at 80°C, swelling time of one day and pH 9.5. The yield was over one third of the original starting waste material.

Separation and Simultaneous Quantitation of Tolterodine Tartrate and Tamsulosin Hydrochloride in Capsule Formulation by using Stability-Indicating RP-HPLC-DAD Method

In the present work, a precise, accurate and selective stability-indicating RP-HPLC method has been developed and validated according to International Conference on Harmonization guidelines Q2-(R1) for the simultaneous quantitative determination of Tolterodine tartrate and Tamsulosin hydrochloride in bulk and its capsule formulation. The chromatographic separation was achieved on Hypersil octadecyl silane C18 (250 x 4.6mm, 5 μm) column at room temperature and mobile phase comprised of methanol: 0.05 M phosphate buffer, pH 7.0 in the ratio of 90:10 V/V. The flow rate of mobile phase was set at 1.0mL/min and compounds were monitored at 255nm using photodiode array detector. Tamsulosin hydrochloride and Tolterodine tartrate retention time were found to be 4.15±0.2 min and 8.42±0.2 min, respectively. The drug substances and products were subjected to acid hydrolysis, alkali hydrolysis, oxidative hydrolysis, photolytic and thermal degradation. The percent degradation of drugs was calculated in all stressed conditions. The analytical method validation parameters such as linearity, accuracy, precision, detection limits, quantitation limits and robustness indicate that drug substances and products were efficiently separated in present of their degradants and successfully applied for the routine analysis of Tolterodine tartrate and Tamsulosin hydrochloride in bulk and its capsule formulation in the quality control laboratory.

Stability Indicating Assay Method Development and Validation of Simultaneous Estimation of Chlorzoxazone, Diclofenac Sodium and Paracetamol in Bulk Drug and Tablet by RP-HPLC

A simple, accurate, specific and stability-indicating RP-HPLC method was developed for simultaneous determination of chlorzoxazone, diclofenac sodium and paracetamol, using C18 Vydac Monomeric 120A (250 × 4.6mm, 5μ) at 40ºC. The mobile phase contains a mixture of 20mM potassium dihydrogen phosphate buffer (pH 6.2 adjusted with potassium hydroxide) and acetonitrile (30:70 v/v). The flow rate was 1ml/min and detection was carried out at 275nm using PDA detector. The retention time of paracetamol, chlorzoxazone and diclofenac sodium were 3.28mins, 13.27mins and 15.61mins respectively. The analytical curve was linear over a concentration range of 0.65- 6.5μg/ml for paracetamol, 1-10μg/ml for chlorzoxazone and 0.1-1μg/ml for diclofenac sodium. The drugs in bulk and tablet were subjected to acid and alkali hydrolysis, oxidation, thermal and photolytic degradation. This method can be successfully employed for simultaneous quantitative analysis of Chlorzoxazone, Diclofenac sodium and Paracetamol in bulk drug and tablet formulation.

Effective bioconversion of feather-waste Keratin by Thermo-Surfactant Stable Alkaline Keratinase produced from Aspergillus sp. DHE7 with promising biotechnological application in detergent formulations

Keratin-rich wastes are troublesome pollutants that their accumulation could lead to environmental problems. Microbial degradation of keratin wastes has emerged as an alternative bio-catalyst to steam-pressure cooking and alkali hydrolysis for the recycling of such residues to value-added products. The current work investigates the purification and biochemical characterisation of an extracellular keratinase from new Aspergillus sp. DHE7 using turkey feathers as substrate. The enzyme was purified 31-fold with a final yield of 37.5%. Purified keratinase is monomeric and its molecular mass was estimated to be 33 kDa as demonstrated on SDS-PAGE. The enzyme was active in wide range of pH (7.0–11) and temperature (37–70 °C) profiles with maximum activity at pH 8.5 and 60 °C. The activity was strongly suppressed by phenylmethylsulfonyl fluoride (93.4% inhibition) and moderately inhibited by EDTA (41.2% inhibition), suggesting that the current keratinase belongs to serine-metalloprotease. Bivalent cations, such as Ca2+, Zn2+, and Mn2+, enhanced enzyme activity by 165.7%, 176.3%, and 194.8%, respectively. The purified keratinase exhibited a wide proteolytic activity towards soluble and insoluble protein substrates displaying its greater activity toward casein, keratin, bovine serum albumin, and gelatin, followed by feathers, goat hair, and wool, and was substantially stable and compliant with surfactants and commercial laundry detergents. The Km, Vmax, Kcat and Kcat/Km values on keratin were 2.2 mg/mL, 2702.7 U/mL, 136.5 s−1 and 62.04 (s−1/mg mL−1), respectively. According to these characteristics, Aspergillus sp. DHE7 keratinase is suggested as a potential candidate for use in detergent formulations (as an additive) and in various biotechnological applications.

Starch Nanoparticles Preparation and Characterization by in situ combination of Sono-precipitation and Alkali hydrolysis under Ambient Temperature

The current work aimed at adopting in situ combination of sono-precipitation and alkali hydrolysis as a rapid technique for starch nanoparticles (SNPs) preparation under ambient conditions with a high yield. Factors affecting the preparation of SNPs were investigated based on statistical analysis using the Box Behnken design. The particle size and polydispersity index of particles were used as dependent variables to obtain the optimized formulation. The SNPs optimized formulation (F14) was further characterized for zeta potential, transmission electron microscopy, Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction. The results of particle size were between 44.82±3.31 and 83.93±8.53 while polydispersity index results were ranged from 0.106±0.012 to 0.179±0.018. The results obtained revealed the efficiency of the technique in obtaining a high yield (98.72% ±0.89) of well-distributed nanoparticles. Also, the SNPs obtained were spherical in shape with good stability, as indicated by zeta analysis (-20±0.25mV) and thermal analysis. The data obtained also showed no change in the chemical structure of the SNPs, as indicated by the infrared transmission of Fourier, thermal analysis, and the relative crystallinity of SNPs was decreased compared with native maize starch indicating the crystallite is transformed from crystalline to amorphous form. The obtained results concluded the efficiency of the adopted method on obtaining SNPs in a short preparation time with a high yield under ambient conditions.

Loosening ultrathin polyamide nanofilms through alkali hydrolysis for high-permselective nanofiltration

Preparation of membranes with both ultrathin thickness and loose structure is often required for high separation performance, but remains a grand challenge. Herein, we report a two-step method to acquire ultrathin loose polyamide (ULPA) nanofilms. More specifically, in the first step, we prepare the ultrathin polyamide nanofilms by support-free interfacial polymerization and in the second step we loosen the ultrathin polyamide nanofilms by alkali hydrolysis. The uniform distribution and diffusion of piperazine at the aqueous-organic interface accelerates the self-sealing and self-healing of interfacial polymerization and generates ultrathin but dense polyamide nanofilms. Further, by hydrolyzing amide bonds with alkali solution, the pore size of polyamide nanofilms is dramatically enlarged. The composite membranes with ULPA nanofilm as separating layer display a water permeance of 29.3 L m−2 h−1 bar−1, 160% higher than that of the pristine polyamide membrane, with an ultrahigh Na2SO4 rejection of 99.1% at 1000 ppm concentration and an outstanding Cl−/SO42− selectivity of 91.8. This ultrathin loose structure may provide a new solution to design membranes with extraordinary permselectivity.

Quantification of β-Adrenergic Receptor Agonist Drug Mirabegron in Presence of Degradants by High Performance Thin Layer Chromatography

A sensitive, selective, accurate, precise and robust thin layer chromatographic method has been developed and validated for the estimation of β-Adrenergic Receptor agonist drug Mirabegron in bulk and pharmaceutical formulation. Aluminium supported plates pre-coated with silica gel 60F-254 was used as stationary phase while methanol: acetonitrile: triethylamine (4: 6: 0.1, v/v/v) mixture saturated in twin trough chamber was used as mobile phase. The Rf values of Mirabegron was observed to be 0.58 ± 0.0089. The detection was carried out in absorbance mode at 247 nm. Linear regression analysis data showed linear relationship for Mirabegron over a concentration range of 100-1200 ng/band. Forced degradation study showed drug was susceptible to acid and alkali hydrolysis, chemical oxidation and photo degradation. The degraded product peaks of Mirabegron were well resolved from the parent peak as data obtained from their significant Rf values. The method was validated and data from forced degradation study showed that the method can be used for quantifying Mirabegron in marketed formulation.

Preparation of cellulose nanofiltration membranes and their removal of typical pollutants from drinking water

Abstract Cellulose membranes have the advantages of good hydrophilicity, excellent mechanical properties, and biodegradability. Therefore, they are the first choice to replace petroleum polymer membranes. In this study, cellulose (BC) and chitosan (CS) were used as raw materials, and N-methylmorpholine-N-oxide (NMMO) was used as solvent. A new kind of cellulose nanofiltration membrane (BC-NFM), cellulose/chitosan nanofiltration membrane (BC/CS-NFM), and interfacial polymerized cellulose/chitosan composite nanofiltration membrane (IP-BC/CS-NFM) were successfully prepared by NaOH hydrolysis and chloroacetic acid carboxymethylation modification, piperazine (PIP), and 1,3,5-trimellitic chloride (TMC) interfacial polymerization, respectively. These two methods were used for the preparation of cellulose nanofiltration membranes for the first time.We also studied their structure, separation performance and their capacity to remove typical pollutants. The results showed that obvious holes appeared on the surface of the nanofiltration membrane obtained by alkali hydrolysis and chloroacetic acid carboxymethylation modification, and the cross-section showed a spongelike structure. The surface of the nanofiltration membrane obtained by interfacial polymerization formed a rough and dense separation layer. The rejection rates of the three kinds of nanofiltration membranes were all over 30% for monovalent salt ions, over 60% for divalent salt ions, over 92% for methyl orange, and over 98% for methyl blue. They had good removal effects for typical pollutants in drinking water.

DEVELOPMENT OF A VALIDATED STABILITY-INDICATING METHOD FOR ESTIMATION OF ETHIONAMIDE IN TABLETS BY RP-HPLC AND CHARACTERIZATION OF ITS ISOLATED ALKALI DEGRADATION PRODUCT

A simple, accurate, reproducible and specific stability-indicating RP-HPLC method was developed for estimation of ethionamide in tablets. Ethionamide was exposed to acid, alkali and neutral hydrolysis at elevated temperatures, to thermolytic degradation, peroxide-mediated oxidation at room temperature in dark and to photolytic degradation. The drug was found stable to thermolytic and photolytic conditions and to neutral hydrolysis. However, substantial degradation was obtained in acid and alkali hydrolysis and complete degradation in peroxide-medicated oxidation. Similar degradation behavior was observed when ethionamide tablets were exposed to the mentioned forced degradation conditions. The method showed adequate resolution of drug from its potential degradation products on C18 (250 × 4.6 mm, 5µ) column using mobile phase of methanol: water (50: 50 % V/V) at 1 mL/min. The drug and its potential degradation products were detected at 290 nm. The method was validated as per the ICH Q2(R1) guidelines. The enrichment of the alkali degradation product was performed and isolated by preparative TLC and further confirmed by NMR and IR spectroscopy.

Establishment of validated stability indicating purity method based on the stress degradation behavior of gonadotropin-releasing hormone antagonist (ganirelix) in an injectable formulation using HPLC and LC-MS-QTOF.

Stress study of a drug substance or pharmaceutical drug product provides a vision into degradation pathways and degradation products of the active pharmaceutical ingredient and helps in interpretation of the chemical structure of the degradation impurities. In the current study, Ganirelix active ingredient presented in the Orgalutran® was stressed with acidic and alkali hydrolysis, photolysis, thermal and oxidation conditions as per the guidelines of International Conference on Harmonization (ICH) Q1A (R2). Ganirelix was found to be labile under thermal and alkali hydrolytic stress conditions, while it was stable to acid hydrolytic, oxidative and photolytic stress. All degradation products were separated with a resolution > 1.5 on a C18 column (2.6 µm, 25 cm×4.6 mm) using a hydrophilic ion pair such as sodium perchlorate, at a concentration <0.04 M. In total, four major degradant impurities were found during stress study. These impurities were fractionated and desalted by flash chromatography for identification of chemical structures. LC-MS-QTOF analysis revealed that two degradation products are diastereomers of Ganirelix, one degradation product is a deamination compound and other degradation product result from the insertion of a new amino acid residue in the Ganirelix peptide sequence. The developed method is sensitive enough to quantify the related substances of Ganirelix at the 0.04% level with that of Ganirelix test concentration.

Extraction and Processing of Pharmaceutical Grade Microcrystalline Cellulose from Dracaena arborea Stem

Cellulose is an abundant renewable biodegradable polymer regarded as a promising feedstock for chemical productions with its versatility evaluated as a useful structural and functional material for pharmaceutical and industrial applications. It is a straight chain polymer which appears in cell walls of most plant and consists of D. glucose units, with absence of coiling or branching and can be derived from variety of sources including: annual plants, microbes, animals etc. Three basic types of cellulose often exist in nature as - alpha (α), beta (β) and gamma (ϒ). Microcrystalline cellulose (MCC) sourced from cellulose, occurs as a purified and partially depolymerized alpha cellulose from plant parts such as D. arborea stem possibly by severe acid or alkaline hydrolysis. D. arborea plant is a palm – like tree of 1.5m height with several branches, often used as a boundary mark, a non-selective habitat and belongs to the family Asparagaceae, sub family Nolinoideae. With alkali hydrolysis of the D. arborea stem, the percentage yield of MCC from the alpha cellulose is 54.32%. Physicochemical analysis of the MCC reveals it to have a pH of 7.80 and physicotechnical analysis resulted in values as recommended in the official monogragh. Proximate principles of the extracted MCC, depicted percentage fiber content as 65.78% and low lipid and protein content as 0.6 and 0.4% respectively. Elemental analysis shows the composition of sodium and iron as 41% and 35% respectively but absence of lead and other deleterious materials. FTIR analysis suggests the presence of carbonyl groups, 6- membered cyclic ring (aromatic structure) with ortho and meta - OH substitution and long aliphatic chains. The x-ray diffraction study gave a percentage crystalinity index of 6.02 at 2q = 22 and 2q = 34.

Ultrasonic-alkali method for synergistic breakdown of excess sludge for protein extraction

Excess sludge is rich in proteins that can be recovered to prepare protein foaming agents and other products with high added value. To extract sludge proteins efficiently, more sludge proteins can be dissolved into the liquid phase by destroying sludge flocs and microbial cell structures. The commonly used alkali-thermal hydrolysis method has the disadvantages of high energy consumption and the additional Maillard reaction. Ultrasonic-alkali hydrolysis (UA) has been widely used as pretreatment for sludge anaerobic digestion, and the effect of UA on cell wall cracking gives it potential application prospects in sludge protein extraction. This study evaluated the potential of UA for sludge protein extraction, and the experimental conditions were optimized to explore the foaming performance of sludge proteins based on a single-factor experiment and orthogonal experiment. The results showed that under optimum hydrolysis conditions (pH of 12, sludge moisture content of 94%, ultrasonic power density of 1.7 W/mL, and ultrasonication duration of 24 min), the protein yield and protein extraction efficiency (RP) were 366.3 mg/g total solids (TS) and 81.4%, respectively. UA converted more than half of the proteins into polypeptides and thus promoted the foaming performance of the sludge proteins to meet the relevant standards for foaming agents. The dewatering performance of the hydrolysed sludge was improved by 93.4%, which was convenient for subsequent treatment. Further research illustrated that UA could shorten the treatment time of alkali hydrolysis (AH) by 36 times when achieving a similar protein yield, and the protein yield produced by UA was 11.4 times greater than that produced solely by ultrasonic hydrolysis (US), indicating that a synergistic effect occurred when AH was combined with US.

Biocidal Activity of Polyester Fabrics Modified with SiO2 Nps

The inorganic nano-sized silicon dioxide modify polyester fabrics using IR dyeing machine was constructed. Chemical activation method with alkali hydrolysis of the fabric was done to facilitate the binding affinity of SiO2 NPs via carboxylic and hydroxyl groups created on the fabric surface. The morphological structure of the treated fabrics was investigated by field-emission scanning electron microscopy (FE-SEM). Dispersive X-ray spectroscopy (EDX) of the untreated and treated polyester fabrics was measured. Fourier transformed infrared spectroscopy (FTIR) of the untreated and treated fabrics was elucidated. TEM of the used silicon dioxide nano particles was monitored. Thermogravimetric analysis (TGA) and UV protection and of the treated fabrics were studied. Antimicrobial activity of finished polyester fabrics containing SiO2 NPs was tested against Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli), and pathogenic fungi (Candida albicans and Aspergillus flavus). The results indicate that the nano-silica has an excellent effect on antimicrobial activity and good protection of both UVA and UVB even after ten washing cycles, indicating the excellent laundering durability. The performance of treated fibers to be used as medical textile was determined by radar chart area.

Extraction and Characterization of Microcrystalline Cellulose from Date Palm Fibers using Successive Chemical Treatments

The aim of present study is to extract microcrystalline cellulose (MCC) from fruit bunch branches fibers of Algerian date palm trees (phoenix dactylifera L) as biofiber for reinforcing green composite and thus replace synthetic fibers in various applications. The extraction of MCC from date palm fibers passed via serial chemical treatments, including alkali, bleaching and acid hydrolysis process. Subsequently, several analyses were implemented to determine the characteristics of each sample prepared at different stages of treatment. Fourier transform infrared spectroscopy (FTIR) analysis revealed the effectiveness in removing substantial amorphous components of lignin and hemicellulose from date palm fibers. Altered and irregular shaped morphology of microfibrils with slightly rougher surface was observed for microcrystalline date palm fibers (MCC-DP) through scanning electron microscope (SEM) examination. Furthermore, X-ray diffraction (XRD) presents the increasing of the crystallinity from 55% in raw date palm (R-DP) to 76.26% in MCC-DP. Also, the results of TGA and DSC indicate the MCC-DP has greater thermal stability than that of R-DP, A-DP and B-DP fibers. These results demonstrate the feasibility of using date palm waste (fruit bunch branches fibers) to extract a good reinforcing material (MCC) with high properties and low cost, which qualifies its use in composite materials. Also, it can be transformed into nano-scale for isolating nanocrystalline cellulose with the aim of using it, in the future to produce ecofriendly bionanocomposites in different fields of applications, biomedical, pharmaceutical and packaging.

A Review on Utilization Routes of the Leather Industry Biomass

The use of biomass to produce bioenergy and biomaterials is considered a sustainable alternative to depleting fossil fuel resources. The world tanneries consume 8–9 MT of skin and hide every year producing 1.4 MT of solid waste. Most of the solid biomass generated from tanneries is disposed of as waste in the environment using either landfilling or thermal incineration. Disposal of this waste into the environment affects the ecosystem, causing bad odor (air pollution) and has an antagonistic impact on the environment. Due to this, European Union legislation bans the landfilling of biomass. This study aims to comprehensively review the possible valorization routes of leather processing industry biomass into high‐value biomaterials. Leather biomass (trimmings, shaving, splitting, and buffing dust) mainly contain 30%–35% collagen protein, which is produced by acid or alkali hydrolysis. The biopolymers obtained from leather industry biomass can be utilized in the production of several high‐value materials. In addition, leather processing industry biomass also contains fat, which can be converted into a bio‐surfactant, and other useful biomaterials. Keratin protein can also be extracted from the hair waste of hides and skins. The increased demand for biomaterials makes the using of leather industry biomass very attractive. From this study, it can be concluded that the conversions of leather processing industry waste to valuable biomaterial can protect the environment, generate additional income for leather industries, and pave way for sustainable and renewable biomaterials production.

Thermal alkali hydrolysis pretreatment of dewatered sludge for protein extraction at low temperature

Thermal alkali hydrolysis pretreatment of dewatered sludge for protein extraction at low temperature

Effect of Oil Content in Tea-seed Pancake on the Determination of Tea Saponin

According to the national standard for the determination of tea saponin content in tea-seed pancake (GB/T 35131-2017), tea saponin was obtained by extracting oil with ethanol and removing solvent. The actual samples of tea-seed pancake did not completely remove the oil, and some of the residual oil content was as high as 9%. Due to the long period of national standard determination, people often use ethanol to extract tea saponin directly, instead of subsequent acid hydrolysis or alkali hydrolysis steps, so as to realize the rapid evaluation of tea-seed pancake quality. In this case, the residual oil has a greater impact on the results. If it was still tested according to the national standard method, the result will be much higher than the actual result. In this work, petroleum ether extraction process was selected before ethanol extraction to remove the residual oil. Experimental results showed that, the accuracy of the determination was effectively improved.

Functional versatility of hybrid composite finishing of chitosan-titania NPs-organic UV-absorber for polyacrylonitrile fabric

This current study proposes a novel, successful method for multi-finishing polyacrylonitrile fabric. The performance of the polyacrylonitrile (PAN) fabric was successfully modified using functional finishing with hybrid composite (chitosan-titania NPs-organic UV absorber). PAN was activated to increase the number of reactive sites available for functional finishing. The effect of the finishing process on the fabric properties and the interaction between the activated PAN fabrics with the hybrid composite was demonstrated. Dyeing with reactive dye was done to monitor the reactive groups formed after alkali hydrolysis of PAN fabric and finishing and has been estimated as the starting point to determine the appropriate finishing bath formulation. The results revealed that the hybrid composite is a multifunctional agent in the fabrication process of bacterial and ultraviolet resistances. The maximum bacterial reduction was 95% E. coli and 92% for S. aureus and the maximum UPF value (108) and excellent protection category against UV radiation. The surface characteristics of the fabrics were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The UPF and antibacterial properties show a minor decrease after five wash cycles. The reduction might be attributable to the unfixed and physically connected finishing agents.

Amino acid sulfonamides based on 4-(1-oxo-1H-isochromen-3-yl)benzenesulfonyl chloride

The creation of new amino acid derivatives of 4-(1-oxo-1H-isochromen-3-yl)benzenesulfonyl chloride 1 was investigated. The interaction of the sulfonyl chloride 1 with amino acid methyl esters (hydrochlorides) in 1,4-dioxane in the presence of triethylamine led to the corresponding amino acid sulfonamide derivatives of isocoumarin. The reaction of the sulfonyl chloride 1 with phenylalanine in the basic aqueous solution was complicated by the lactone system disclosure and led to 2'-carboxydeoxybenzoin ultimately (namely, 2-(2-(4-(N-(1-carboxy-2-phenylethyl)sulfamoyl)phenyl)-2-oxoethyl)benzoic acid). Similar product was obtained by the alkali hydrolysis of methyl ((4-(1-oxo-1H-isochromen-3-yl)phenyl)sulfonyl)leucinate.