scholarly journals Nitroaromatic Compounds, from Synthesis to Biodegradation

2010 ◽  
Vol 74 (2) ◽  
pp. 250-272 ◽  
Author(s):  
Kou-San Ju ◽  
Rebecca E. Parales
Keyword(s):  
Nitro Group ◽  
Aromatic Amines ◽  
Environmental Remediation ◽  
Oxidative Degradation ◽  
Nitroaromatic Compounds ◽  
Important Class ◽  
Industrial Chemicals ◽  
Evolutionary Origins ◽  
The Stability ◽  
The U.S

SUMMARY Nitroaromatic compounds are relatively rare in nature and have been introduced into the environment mainly by human activities. This important class of industrial chemicals is widely used in the synthesis of many diverse products, including dyes, polymers, pesticides, and explosives. Unfortunately, their extensive use has led to environmental contamination of soil and groundwater. The nitro group, which provides chemical and functional diversity in these molecules, also contributes to the recalcitrance of these compounds to biodegradation. The electron-withdrawing nature of the nitro group, in concert with the stability of the benzene ring, makes nitroaromatic compounds resistant to oxidative degradation. Recalcitrance is further compounded by their acute toxicity, mutagenicity, and easy reduction into carcinogenic aromatic amines. Nitroaromatic compounds are hazardous to human health and are registered on the U.S. Environmental Protection Agency's list of priority pollutants for environmental remediation. Although the majority of these compounds are synthetic in nature, microorganisms in contaminated environments have rapidly adapted to their presence by evolving new biodegradation pathways that take advantage of them as sources of carbon, nitrogen, and energy. This review provides an overview of the synthesis of both man-made and biogenic nitroaromatic compounds, the bacteria that have been identified to grow on and completely mineralize nitroaromatic compounds, and the pathways that are present in these strains. The possible evolutionary origins of the newly evolved pathways are also discussed.

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

Addition of Aliphatic and Aromatic Amines to Catechol in Aqueous Solution Under Oxidizing Conditions

1989 ◽  
Vol 42 (3) ◽  
pp. 365 ◽  
Author(s):  
MK Manthey ◽  
SG Pyne ◽  
RJW Truscott
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Aromatic Amines ◽  
Aliphatic Amines ◽  
Substitution Pattern ◽  
Vinylogous Amides ◽  
The Stability

The oxidation of catechol in the presence of two aliphatic and aromatic amines has been investigated. In aqueous solutions of pH 7.0 and 11.7, the substitution pattern of the adduct was dependent on the type of amine used. Aromatic amines produced 4,5-disubstituted o-quinones, whereas aliphatic amines gave either 2,4,5-trisubstituted or 2,4-disubstituted o-quinone adducts. A rationale based upon the stability of vinylogous amides is presented to account for the observed substitution pattern.

Stability of dronabinol capsules when stored frozen, refrigerated, or at room temperature

2016 ◽  
Vol 73 (14) ◽  
pp. 1088-1092 ◽  
Author(s):  
Michael F. Wempe ◽  
Alan Oldland ◽  
Nancy Stolpman ◽  
Tyree H. Kiser
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Oxidative Degradation ◽  
Storage Condition ◽  
Sesame Oil ◽  
Forced Degradation ◽  
Product Packaging ◽  
Time Points ◽  
The Stability ◽  
Minimal Reduction

Abstract Purpose Results of a study to determine the 90-day stability of dronabinol capsules stored under various temperature conditions are reported. Methods High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was used to assess the stability of dronabinol capsules (synthetic delta-9-tetrahydrocannabinol [Δ9-THC] mixed with high-grade sesame oil and other inactive ingredients and encapsulated as soft gelatin capsules) that were frozen, refrigerated, or kept at room temperature for three months. The dronabinol capsules remained in the original foil-sealed blister packs until preparation for HPLC–UV assessment. The primary endpoint was the percentage of the initial Δ9-THC concentration remaining at multiple designated time points. The secondary aim was to perform forced-degradation studies under acidic conditions to demonstrate that the HPLC–UV method used was stability indicating. Results The appearance of the dronabinol capsules remained unaltered during frozen, cold, or room-temperature storage. Regardless of storage condition, the percentage of the initial Δ9-THC content remaining was greater than 97% for all evaluated samples at all time points over the three-month study. These experimental data indicate that the product packaging and the sesame oil used to formulate dronabinol capsules efficiently protect Δ9-THC from oxidative degradation to cannabinol; this suggests that pharmacies can store dronabinol capsules in nonrefrigerated automated dispensing systems, with a capsule expiration date of 90 days after removal from the refrigerator. Conclusion Dronabinol capsules may be stored at room temperature in their original packaging for up to three months without compromising capsule appearance and with minimal reduction in Δ9-THC concentration.

scholarly journals Buffer Additives and Packaging Differentially Influence the Stability of Dyes Commonly Used in Chromovitrectomy

2016 ◽  
Vol 1 (3) ◽  
pp. 1-10
Author(s):  
Begoña Parrado Aliod ◽  
Wilfried Kugler ◽  
Tim Häring
Keyword(s):  
Polyethylene Glycol ◽  
Chemical Stability ◽  
Deuterium Oxide ◽  
Oxidative Degradation ◽  
Bromophenol Blue ◽  
Physiological Range ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Acid Violet ◽  
Dye Solutions

Purpose: This study was performed to investigate the chemical stability of different dyes used in chromovitrectomy and the influence of various product parameters on it. Methods: Buffered dye solutions were prepared containing 1.5 g/L acid violet 17, 0.25 g/L brilliant blue G, 1.3 g/L bromophenol blue, and 1.5 g/L trypan blue, combined with deuterium oxide, polyethylene glycol 3350, and D-mannitol as additives. For accelerated storage testing, samples were incubated for 400 h at 80°C corresponding to 2 years according to the Van ‘t Hoff equation. After different incubation times samples were taken for UV/Vis spectroscopy, pH measurement, and osmometry. Results: Depending on dye, additive, and packaging, different solutions exhibit differences in chemical stability and hence shelf life. Packaging in syringes instead of vials increases dye stability. Additives may negatively influence important parameters, e.g. polyethylene glycol 3350 increases osmolality beyond the physiological range. Notably, acid violet 17 is chemically unstable except in D-mannitol-containing buffer, packed in syringes. However, simultaneously, D-mannitol leads to a pH shift below 7.0. Conclusion: In summary, dye solutions filled in syringes should be preferred to vials to slow down oxidative degradation. Especially acid violet 17 solutions should be used with caution because the addition of D-mannitol may contribute to pH values beyond the physiological range.

scholarly journals The ANZUS Treaty during the Cold War: A Reinterpretation of U.S. Diplomacy in the Southwest Pacific

2015 ◽  
Vol 17 (4) ◽  
pp. 109-157 ◽  
Author(s):  
Thomas K. Robb ◽  
David James Gill
Keyword(s):  
World War Ii ◽  
New Zealand ◽  
Regional Cooperation ◽  
Coercive Diplomacy ◽  
Monetary System ◽  
The Pacific ◽  
Self Interest ◽  
The Stability ◽  
The Cold War ◽  
The U.S

This article explains the origins of the Australia–New Zealand–United States (ANZUS) Treaty by highlighting U.S. ambitions in the Pacific region after World War II. Three clarifications to the historiography merit attention. First, an alliance with Australia and New Zealand reflected the pursuit of U.S. interests rather than the skill of antipodean diplomacy. Despite initial reservations in Washington, geostrategic anxiety and economic ambition ultimately spurred cooperation. The U.S. government's eventual recourse to coercive diplomacy against the other ANZUS members, and the exclusion of Britain from the alliance, substantiate claims of self-interest. Second, the historiography neglects the economic rationale underlying the U.S. commitment to Pacific security. Regional cooperation ensured the revival of Japan, the avoidance of discriminatory trade policies, and the stability of the Bretton Woods monetary system. Third, scholars have unduly played down and misunderstood the concept of race. U.S. foreign policy elites invoked ideas about a “White Man's Club” in Asia to obscure the pursuit of U.S. interests in the region and to ensure British exclusion from the treaty.

FDA Total Diet Study, July 1986-April 1991, Dietary Intakes of Pesticides, Selected Elements, and Other Chemicals

1995 ◽  
Vol 78 (6) ◽  
pp. 1353-1362 ◽  
Author(s):  
Gunderson Ellis L.
Keyword(s):  
Metropolitan Areas ◽  
Sampling Period ◽  
Dietary Intakes ◽  
Industrial Chemicals ◽  
Population Groups ◽  
Total Diet Study ◽  
Total Diet ◽  
Diet Study ◽  
Daily Intakes ◽  
The U.S

Abstract The U.S. Food and Drug Administration conducts the Total Diet Study to determine dietary intakes of selected pesticides, industrial chemicals, and elements (including radionuclides). This paper reports results for the sampling period July 1986 to April 1991. The study involves retail purchase of foods representative of the "total diet" of the U.S. population, preparation for "table-ready" consumption, and individual analyses of 234 items making up the diets of 8 population groups. The diets were based on 2 nationwide food consumption surveys. The data presented represent 21 food collections (also termed "market baskets") in regional metropolitan areas during the 5-year period. Dietary intakes of nearly 120 analytes are presented for 8 population groups, which range from infants to elderly adults. Intakes of selected population groups are compared with representative findings from earlier Total Diet Study sampling periods. As reported previously, average daily intakes are well below acceptable limits.

Performance of Two Immunochemical Assays in the Analysis of Peanuts for Aflatoxin at 37 Field Laboratories

1993 ◽  
Vol 76 (3) ◽  
pp. 637-643 ◽  
Author(s):  
Joe W Dorner ◽  
Paul D Blankenship ◽  
Richard J Cole
Keyword(s):  
Liquid Chromatography ◽  
Assay System ◽  
Department Of Agriculture ◽  
Joint Project ◽  
Rapid Assay ◽  
Additional Information ◽  
Relative Standard ◽  
Standard Deviations ◽  
The Stability ◽  
The U.S

Abstract A study was conducted to measure the precision of 2 rapid aflatoxin assay systems in use at 37 peanut buying points during the 1991 harvest season. Aflatoxin laboratories were established at the 37 buying points to analyze peanut samples from all incoming farmers’ stock loads as part of a joint project sponsored by various segments of the U.S. peanut industry and the U.S. Department of Agriculture. Eighteen laboratories were equipped with Neogen’s veratox FSP rapid assay system, whereas 19 laboratories used Vicam’s Aflatest rapid assay system. To monitor the performance of the field laboratories during the project, 3 portions of each of six 27 kg samples of ground peanuts were sent to each laboratory for analysis over a period of 6 weeks. Aflatoxin concentrations ranged from 0 to 300 ng/g when eight 200 g subsamples of each sample were analyzed by liquid chromatography (LC). For the 5 samples contaminated with aflatoxin, relative standard deviations for repeatability (RSDr) for laboratories using veratox FSP ranged from 18.66 to 53.29%, and the relative standard deviations for reproducibility (RSDR) ranged from 22.79 to 59.29%. For laboratories using the Aflatest system, RSDr values ranged from 18.70 to 41.48%, and RSDR values ranged from 23.84 to 47.56%. Horwitz ratios < 2.0 were found for 4 of the 5 contaminated samples for both methods, indicating that the overall precision of the 2 methods used in the project was good. Mean aflatoxin concentrations, as determined with the rapid assay systems, were generally lower than those determined by LC, particularly for more highly contaminated samples. This could not be attributed to instability of aflatoxin in peanut paste, because additional information gathered in the study indicated that the stability of aflatoxin in peanut paste stored for 58 days was good.

A Dialogue-Centric Approach to Environmental-Remediation Decision-Making

2011 ◽  
Author(s):  
Laurel Boucher ◽  
James F. Clark
Keyword(s):  
Decision Making ◽  
Department Of Defense ◽  
Environmental Remediation ◽  
Leadership Skills ◽  
Decision Making Process ◽  
Remediation Plan ◽  
The Impact ◽  
The U.S ◽  
Poor Management ◽  
Responsible Party

This paper outlines a multi-step approach to streamline and enhance the decision-making process that guides environmental remediation. The inability of the responsible party and the various stakeholders to reach agreement on the remediation plan can delay the remediation, result in financial penalties, and lead to the development of an adversarial stance that inhibits the ability of the parties to work together in a creative and constructive manner. The approach presented by the authors is designed to expand dialogue in a way that moves it beyond technical or fiscal matters by addressing what the authors describe as the “hidden barriers” to productive dialogue. These “hidden barriers” include: self-interests, the perception as to how people are being treated, a lack of clarity or poor management of responsibilities and accountabilities, unclear or convoluted communication protocols, and an underlying tone of conflict and cynicism. A key element of the multi-step approach outlined in this paper is the process of uncovering these “hidden barriers” and addressing them in a way that turns discourse into collaboration. The paper describes a model the authors have used to streamline and enhance the process of creating sustainable agreements both for the U.S. Department of Energy’s Office of Environmental Management as well as the U.S. Department of Defense for a variety of environmental remediation projects. The results of this approach include the acceleration of an environmental clean-up from a projected 19 years to 11 years, the development of innovative technical strategies, the reduction of a major backlog of environmental proposals requiring review and comment, and the distinction accorded one group of being recognized as a model of effective partnering. The approach described has widespread implications not only because its use can be expanded to include a multitude of decision-making applications but also because of the impact it creates by expanding both the management and leadership skills of those who use it.

Sign in / Sign up

Export Citation Format

Share Document