Green Synthesis of o-Phenyl-benzothiazole

Green Synthesis of o-Phenyl-benzothiazole Green Condensation of o-Aminothiophenol to o-Phenyl-benzothiazole David Fairchild, Alex Irion, Dominic Russo, Luke Sanders Abstract Herein we describe a simple, efficient, and environmentally friendly synthesis of o-arylbenzothiazoles, such as o-phenyl-benzothiazole, under standard ambient temperature and pressure via reaction of o-aminothiophenols with aromatic aldehydes using glycerol as a solvent. The combined characteristics of glycerol allow it to act as both a green and biodegradable solvent, but its high polarity also catalyzes the reaction between various o-aminothiophenols and aromatic aldehydes, hence replacing the need for expensive, and often environmentally hazardous, solvents or catalysts. Land management Water conservation clean-up Green Condensation of o-Aminothiophenol to o-Phenyl-benzothiazole Problem Numerous o-arylbenzothiazoles can be found in a variety of biologically occurring compounds, and they are becoming an increasingly important family of antitumor agents (Kashiyama E et al., 1999)1; moreover, these compounds exhibit biological activity as antituberculosis agents and antiparasitics (Yamamoto K et al., 1998)2, but also serve as useful imaging agents for ÃŽ ²-amyloid (Lee BC et al., 2011)3. Traditionally, most o-arylbenzothiazoles are synthesized by either arylation of benzothiazole with aryl bromides and catalyzed by palladium (II) acetate, copper (I) bromide, or tri-tert-butylphosphine (Vattoly J. Majo, Jaya Prabhakaran, J.John Mann, J.S. Dileep Kumar, 2003)4 or via condensation of o-aminothiophenols by varying functional groups with a number of different catalysts including: trimethylsilyl chloride (S. V. Ryabukhin, A. S. Plaskon, D. M. Volochnyuk, A. A. Tolmachev, 2006)5, manganese (II) oxide (Cecilia D. Wilfred Richard J. K. Taylor, 2004)6, or 1-methyl-3-pentylimidazo-lium bromide (Brindaban C. Ranu, Ranjan Jana, Suvendu S. Dey, 2004)7. Nevertheless, there have been several recent and more environmentally friendly procedures for synthesizing o-arylbenzothiazoles, such as with a mixture of sulfuric acid and silicon dioxide to act as a catalyst (Behrooz Maleki et al., 2010)8, or with p-toluenesulfonic acid in water (Najmedin AziziAlireza et al., 2009)9; however, m any of these recent discoveries require high temperatures, lengthy reaction times, and sometimes result in relatively low yield. In addition, many of the catalysts employed in the traditional reactions are both economically and environmentally costly, thus often resulting in serious environmental pollution, which may affect important waterways for many ecological systems. An important tenet of green chemistry is the minimal use of auxiliary substances and the use of innocuous solvents whenever possible; solvents play a major role in the environmental performance of chemical processes, but also impact cost, safety, and operational health. Thus, the purpose behind green solvents expresses the goal to minimize the environmental impact resulting from the use of solvents in chemical procedures; hence, many of these solvents exhibit similar properties, including: low volatility, low cost, high reusability, low toxicity, low flammability, and high solvation power for both inorganic and organic compounds. Glycerol is one such compound that has recently garnered much attention as a result of these aforementioned qualities since it combines many of the characteristics of water with many of the benefits of ionic liquids. We have therefore chosen this project because the field of green chemistry is an ever-growing and an ever-more-important subfield of chemistry, and because a better and more efficient synthesis of o-phenylbenzothiazole and other o-arylbenzothiazoles will have practical applications toward minimizing potential environmental waste from the preparation of an increasingly important research pharmaceutical. Hypothesis If glycerols high polarity and solvation ability were able to act as a functional group on aromatic aldehydes, then o-phenylbenzothiazole could be produced by simple condensation of o-aminothiophenol. Experimentation Due to the limited availability of many of the basic reagents required for this experiment, we plan on first synthesizing many of the preparatory reagents on a micro scale; these chemicals are more easily available in bulk, and, hence, the following procedures would be unnecessary in practice. The following preparations include: Preparation of Nitrobenzene by Mixed Acid Nitration of Benzene Nitrobenzene is produced by simple nitration of benzene with nitric acid and sulfuric acid acting as catalysts. A 500 ml flask is charged with a stir bar and 8 ml of concentrated 98% sulfuric acid and 84.013 ml of concentrated 90% nitric acid is added slowly (note 1). Once the solution of acids cools, 182.687 ml of benzene is slowly added to the flask (note 2). Once all the benzene is added, the contents of the flask are poured into an appropriate separatory funnel and the bottom aqueous layer is discarded. The crude nitrobenzene is then washed with 40ml of distilled water three times to remove excess acids; once complete, an appropriate round bottom flask (RBF) is charged with the bottom layer (crude nitrobenzene), and the top layer is discarded. A simple distillation of the crude nitrobenzene is performed collecting the fraction between 207Â ° C and 211Â ° C. This distillate is then dried with calcium chloride, and filtered off for future use yielding approximately 170.37 ml of pure nitrobenzene (~83% theoretical yield based on nitric acid). Preparation of Aniline by Reduction of Nitrobenzene Aniline is synthesized by a modified procedure outlined in Vogel (5, p. 892)10. 178.065 g of tin powder,140 ml of distilled water, and 564.972 ml of 38% hydrochloric acid are charged into a two-way 1 L RBF along with a suitable stir bar. A thermometer and a pressure-equalizing additional funnel with 102.636ml of the previously prepared nitrobenzene are clamped to the RBF. The RBF is placed on a hot plate and slowly heated and stirred while nitrobenzene is slowly added (note 3); upon completion, the solution is set up for reflux for 30 minutes. Thereafter, 39.997 g of sodium hydroxide are added, and the solution is set up for steam distillation. The collected distillate from the previous steam distillation is placed in a suitable separatory funnel, where it is washed with a saturated brine solution. The top layer of aniline is then placed in another suitable RBF and setup for simple distillation; this distillation is carried out until the temperature reaches 130Â ° C. The collected distillate is then redistilled with the fraction between 180Â ° C and 184Â ° C collected (note 4). The final distillate of 90.336 ml (~97% yield based on nitrobenzene) is then poured into a suitable container for storage and future use. Preparation of Acetanilide Acetanilide is prepared by simple acetylation of the previously prepared aniline with acetic anhydride. 77.479 ml of the previously prepared aniline are charged into a 250 ml RBF, and 20 ml of water are added with an additional 2 ml of 38% hydrochloric acid so that the previous two layers mix; a stir bar is also charged in the flask. The solution of aniline hydrochloride is gently heated while stirring is begun. A mixture of 80.200 ml of acetic anhydride are added and 4.5 g of sodium acetate is quickly added all at once. Heat is removed, while vigorous stirring is maintained. The white acetalanilide precipitate is then vacuum-filtered off and then washed with cold water, yielding approximately110.96 g of product with a m.p. between 112Â ° C to 115Â ° C. Preparation and Separation of o-Nitroaniline from Acetanilide o-Nitroaniline is prepared by a slightly modified mixed acid nitration of acetanilide. 100g of the previously prepared dry acetanilide is charged into a two-neck 100 ml RBF along with a suitable stir bar. This set up is placed over a magnetic stirrer (note 5), and a pressure-equalizing addition funnel containing 31.079 ml of 90% nitric acid, 2 ml of 98% sulfuric acid (note 6), and a thermometer are clamped to the RBF. The mixed acids are then slowly added drop-wise in 2 ml portions every ten minutes to allow for adequate cooling of the reaction. Once the acid addition is complete, the addition funnel is removed, and 15 ml of ice water are added, heated to reflux allowing the nitroacetanilides to hydrolyze. After approximately 15 to 20 minutes, the reaction is allowed to cool; once cooled, an equimolar amount of sodium hydroxide (based on acetanilide) is very slowly added to the RBF. The crude mixture nitroacetanilides is then filtered off and dried. This crude product is recrystallized from hot ethanol, thus allowing the p- and o- isomer to separate. The crystals are filtered off and stored for later use, however, the filtrate, which predominately contains o-nitroaniline, is set up for column chromatography with methylene chloride for further purification. Afterwards, the methylene chloride is allowed to evaporate off, yielding approximately 35.621 g of o-nitroaniline with a m.p. between 69Â ° C and 75 Â ° C. Preparation of o-Chloronitrobenzene from o-Nitroaniline Hartman and Brethen (1923)11 found that m-chloronitrobenzene can be synthesized by formation of the diazonium salt from m-nitroaniline. Based on their procedure, o-chloronitrobenzene is similarly synthesized from the previously prepared o-nitroaniline. A 500ml RBF is charged with 15 g of o-nitroaniline and with an equimolar amount of 38% hydrochloric acid, along with an additional 250 ml of hot water, a stir bar, and an additional equimolar amount of hydrochloric acid, and this set up is then placed over a magnetic stirrer. The entire mixture is cooled, and 20 g of sodium nitrite are added slowly with heavy stirring; once this addition is complete, the solution is filtered to remove any amorphous solids. A suitable two-neck RBF is charged with a mixture containing 14.251 g of cuprous chloride in 38% hydrochloric acid; a thermometer and powder addition funnel containing the previously prepared o-nitrobenzenediazonium chloride are clamped to the flask. o-Nitrobenzenediazonium chloride then is very slowly added to the flask over a period of one hour. After this addition is complete, the mixture is set up for reflux until nitrogen stops evolving from the flask, after which the solution is set up for simple steam distillation until no more o-chloronitrobenzene comes over. The distillate is cooled to allow the o-chloronitrobenzene to crystallize; this crude distillate is washed with sodium hydroxide and then with cold water, resulting in approximately 29 g of o-chloronitrobenzene (~62% theoretical yield based on o-nitroaniline). Synthesis of o-Aminothiophenol by Sulfunation of o-Chloronitrobenzene o-Aminothiophenol is synthesized by a modified procedure outlined in US Patent No. 3931321 (1976)12. 10 g of the previously prepared o-chloronitrobenzene with 80 ml of water are charged into a 250 ml RBF. Paraffin oil is used instead of the special emulsion polymerizer outlined in the original patent; the mixture is strongly stirred, and an addition funnel containing solution 15.022 g of sodium sulfide and an equimolar amount of sodium hydroxide is clamped to the flask; the solution is added slowly over 10 minute intervals with periods of cooling in between. The mixture is heated between 100Â ° C and 110Â ° C for approximately two hours. The product is set up for steam distillation until a clear distillate comes over. To this clear distillate, .5 g of activated carbon is added, and the mixture is washed with cold toluene; for further work up, the product is then washed 38% hydrochloric acid until the pH is adjusted to six, and the mixture is poured into a separatory funnel from which the bottom aqueous layer is removed. Excess toluene is then removed by simple distillation, and this distillate is allowed to cool. Approximately 5.461 g of o-aminothiophenol crystallizes (~78.37% yield based on o-chloronitrobenzene) with a m.p. between 22Â ° C and 25Â ° C. Synthesis of Benzaldehyde by Oxidation of Benzyl Alcohol Benzaldehyde is synthesized by simple oxidation of benzyl alcohol. A two neck 500 mL RBF is setup with a ring stand and wire mesh pad. A Bunsen burner is then placed below the apparatus, and the RBF is charged with an appropriate stir bar and 103.5 g of sodium persulfate dissolved in a minimum quantity of water. A pressure-equalizing funnel containing 30 ml of benzyl alcohol and a reflux condenser are clamped to the flask. This set up is then heated to reflux while benzyl alcohol is slowly added drip-wise; once all the benzyl alcohol is completely added, the Bunsen burner is extinguished, and replaced with a magnetic stirrer until the solution cools down. Upon cooling, the RBF is setup for steam distillation. The distillate is then poured into a separatory funnel, and the bottom crude benzaldehyde is separated out; this crude product is then dried over magnesium sulfate. Once dried, the benzaldehyde is placed in a suitable RBF and fractionally distilled under vacuum at approximately .109 atm; the fraction between 91Â ° C and 93Â ° C is collected, leaving 19.35 ml of pure benzaldehyde (~65% theoretical yield based on benzyl alcohol). Synthesis of o-Phenyl-benzothiazole from o-Aminothiophenol and Benzaldehyde 2 g of the previously prepared o-aminothiophenol and 1.695 g of benzaldehyde are charged into a 25 ml Erlenmeyer flask with 15 ml of glycerol. The reaction is heated for one hour. Afterwards, water is added until precipitate no longer fell out of solution; the precipitate is purified via recrystallization in hot ethanol, thus resulting in 3.034 g of o-phenyl-benzothiazole with a m.p. between 112Â ° C and 114Â ° C. Works Cited Kashiyama E1, Hutchinson I, Chua MS, Stinson SF, Phillips LR, Kaur G, Sausville EA, Bradshaw TD, Westwell AD, Stevens MF. (1999, Oct 7). Antitumor benzothiazoles. 8. Synthesis, metabolic formation, and biological properties of the C- and N-oxidation products of antitumor 2-(4-aminophenyl)benzothiazoles. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10514287 Yamamoto K1, Fujita M, Tabashi K, Kawashima Y, Kato E, Oya M, Iso T, Iwao J. (1988, May 31). Novel calcium antagonists. Synthesis and structure-activity relationship studies of benzothiazoline derivatives. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/3361580 Lee BC1, Kim JS, Kim BS, Son JY, Hong SK, Park HS, Moon BS, Jung JH, Jeong JM, Kim SE. (2011, May 1). Aromatic radiofluorination and biological evaluation of 2-aryl-6- [18F]fluorobenzothiazoles as a potential positron emission tomography imaging probe for ÃŽ ²-amyloid plaques. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21478020 Vattoly J. Majo, Jaya Prabhakaran, J.John Mann, J.S. Dileep Kumar (2003, November 17). An efficient palladium catalyzed synthesis of 2-arylbenzothiazoles. Retrieved from http://www.sciencedirect.com/science/article/pii/S004040390302272X S. V. Ryabukhin, A. S. Plaskon, D. M. Volochnyuk, A. A. Tolmachev (2006). Synthesis of Fused Imidazoles and Benzothiazoles from (Hetero)Aromatic ortho-Diamines or ortho- Aminothiophenol and Aldehydes Promoted by Chlorotrimethylsilane. Retrieved from http://www.organic-chemistry.org/abstracts/lit1/493.shtm Cecilia D. Wilfred Richard J. K. Taylor (2004, December 3) Tandem oxidation processes for t he preparation of nitrogen-containing heteroaromatic and heterocyclic compounds. Retrieved from http://pubs.rsc.org/en/Content/ArticleLanding/2004/OB/b315689c#!divAbstract Brindaban C. Ranu, Ranjan Jana, Suvendu S. Dey (2004, February 2). An Efficient and Green Synthesis of 2-Arylbenzothiazoles in an Ionic Liquid, [pmIm]Br under Microwave Irradiation. Retrieved from https://www.jstage.jst.go.jp/article/cl/33/3/33_3_274/_article Maleki B, Salehabadi H, Moghaddam MK (2010, September 5). Room-Temperature Synthesis of 2-Arylbenzothiazoles using Sulfuric Acid Immobilized on Silica as a Reusable Catalyst under Heterogeneous Condition. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/24061824 Najmedin Azizi, Alireza Khajeh Amiri, Roya Baghi, Mohammad Bolourtchian, Mohammad M. Hashemi (2009, July 21). PTSA catalyzed simple and green synthesis of benzothiazole derivatives in water. Retrieved from http://link.springer.com/article/10.1007/s00706- 009-0209-4 A.I. Vogel, A.R. Tatchell, B.S. Furnis, A.J. Hannaford, P.W.G. Smith (1996). Vogels Textbook of Practical Organic Chemistry (5th ed.). New Jersey: Prentice Hall W. W. Hartman M. R. Brethen (1923). Organic Syntheses (3rd ed.). Planker, Siegfried Baessler, Konrad (1976) US Patent No. 3931321 Washington, DC: U.S. Patent and Trademark Office.

Booker T. Washington :: essays research papers

I’m Booker T Washington In 1881, I founded and became principal of Tuskegee Normal and Industrial Institute. I started this school in an old abandoned church and a shanty. The school's name was later changed to Tuskegee Institute (now Tuskegee University). The school taught specific trades, such as carpentry, farming, and mechanics, and trained teachers. As it expanded, I spent much of his time raising funds. Under Washington's leadership, the institute became famous as a model of industrial education. The Tuskegee Institute National Historic Site, established in 1974, includes Washington's home, student-made college buildings, and the George Washington Carver Museum. I believe that blacks could benefit more from a practical, vocational education rather than a college education. Most blacks lived in poverty in the rural South, and I felt they should learn skills, work hard, and acquire property. I believed that the development of work skills would lead to economic prosperity. I predicted that blacks would be granted civil and political rights after gaining a strong economic foundation. I explained his theories in Up from Slavery and in other publications. In the late 1800's, more and more blacks became victims of lynchings and Jim Crow laws that segregated blacks. To reduce racial conflicts, I advised blacks to stop demanding equal rights and to simply get along with whites. I urged whites to give black better jobs. In a speech given in Atlanta, Georgia, in 1895, I declared: "In all things that are purely social we can be as separate as the fingers, yet one as the hand in all things essential to mutual progress." This speech was often called the Atlanta Compromise because I accepted inequality and segregation for blacks in exchange for economic advancement. The speech was widely quoted in newspapers and helped make me a prominent national figure and black spokesman. I became a shrewd political leader and advised not only Presidents, but also members of Congress and governors, on political appointments for blacks and sympathetic whites. I urged wealthy people to contribute to various black organizations. I also owned or financially supported many black newspapers. In 1900, I had founded the National Negro Business League to help black business firms. Throughout my life, I tried to please whites in both the North and the South through his public actions and his speeches. I never publicly supported black political causes that were unpopular with Southern whites.

Financial Statements Essay

There are four basic financial statements that companies use. They begin with income statement, statement of owner’s equity, balance sheet, and the statement of cash flows. Company’s use income statements to report how much money they have made and how much they have spent over a specified period of time. The statement of owner’s equity is used to report any changes in equity from a company’s net income or net loss, as well as report changes in the owner’s investments and withdrawals over a specified period of time. The balance sheet is used to report a company’s financial position at any point in time. This statement includes information such as what types of assets and their amounts, liabilities, and equity. The statement of cash flows is the last document out of the four basic financial statements. This statement is used to report how much money a company is bringing in (receipts), and how much they are spending (payments), during a specific period of time. Any changes found in assets and liabilities on a balance sheet reflect the revenues and expenses found in the income statement, which in turn results in gains or losses for a company. The statement of cash flows reports more information concerning the cash assets that are listed on a balance sheet and a linked, but not necessarily the same, as the net income found on the company’s income statement. Financial statements are nothing but numbers on a document when they’re on their own, but together, they provide valuable and powerful information for a company to make very big decisions about how to run their company, and how to make decisions for their company in the future. The information is also valuable for investors to make wise and educated decisions for investing in companies.

Indigenous Rights in Canada - Free Essay Example

Sample details Pages: 3 Words: 882 Downloads: 1 Date added: 2018/12/19 Category Law Essay Type Research paper Level High school Tags: Canada Essay Government Essay Did you like this example? Terrible Acts besides Indigenous individuals Canadian government recognizes three different types of indigenous individuals. These include Indians, Metis as well as Inuit. Indigenous individuals have always been victims of acts against them like colonization of their households, built -up schools as well as cultural killing. Don’t waste time! Our writers will create an original "Indigenous Rights in Canada" essay for you Create order There is gap that has been pointed between rights for non-indigenous and indigenous. In addition, staying in one of the wealthy states across the realm, indigenous individuals in Canada come across problems such as impoverishment, residential problems, challenges in accessing medical care, clean water and getting food for themselves and their families. They are even forced to deal with repercussions of built-up schools. Although, the government of Canada claims to use a lot of money on the indigenous individuals, funding for their necessities like their food, shelter and water is less when compared to what non indigenous societies get. The paper will critically seek to analyze the rights of indigenous people, both their past and present events and promises for their future. The paper will also highlight discrimination and injustices in a non-bias way with solids proofs. History Before the coming of European settlers in Canada, indigenous individuals occupied as well as thrived on land in around 1200 years ago. They used this land and their resources as a way of surviving. They acknowledged their God for what he had provided them. They stayed a holy life and treated their lands with a lot of respect. When settlers arrived, their lands were taken away and displaced from those lands. Residential Schools One hundred and thirty residential schools were established till the year 1870. The Canadian government was involved in funding operations for these residential schools along with numerous religious organizations like Roman Catholic churches. The main aims of these schools were to eliminate and isolate youngsters from their households, families, beliefs as well as to assimilate them into the central cultures in Canada. During this time, many 150,000 indigenous youngsters were eliminated as well as alienated from their own relatives and societies in order to attend residential schools. They were also forced to conform to beliefs, cultures and views of Catholic. Although residential schools were operated for numerous years, they ceased to operate in the year 1996. Many of the youngsters survived in an unconducive and unfavorable environments while at those residential schools whereby resulting effects and traumas may be seen nowadays within those indigenous people. According to article Residential school survivor, Cynthia Wesley-Esquimaux, There was more clean water for drinking, and because they were out from residential schools, there was sexual harassment and domestic violence. Thus, many of the children were under sexual harassment and domestic violence toward binging of drinking water. Cynthia tries to describe trauma which had been passed from generation to generation because of injustices and discrimination faced by the indigenous population. Therefore, assimilation of the culture of indigenous people, discrimination and colonization have dominant roles to the problem faced by these people nowadays. Truth and Reconciliation The fact and Resolution Committee refers to an organization devoted to receiving the facts and reconciliation coming from the government. The fact and resolution committee was established in 1996. It has been forcing the government to acknowledge and apologize for the wrongs which have been done to indigenous people in past and present. The objective of this organization is to better the lives of those affected in forthcoming future. It also calls for actions that should be done by administration of Canada. The Indian Act The Act was amended in year1876. This permitted the administration of Canada to take control of many aspects of indigenous population such as the status of Indians, lands, and their education. In addition, Indian act considered how much funds would be used in systems of reserves and concerns for indigenous individuals. The act has been updated several times but, in modern days, it is prejudiced to indigenous individuals. Before this period, the royal proclamation bill of 1763, was the one that government worked on. It showed the people whom indigenous population was supposed to interact. The bill also gave some rights to the indigenous population and centered on how they could stay. Moreover, the bill made it easier for European settlers to take the lands and resources from indigenous people. The act showed factors that should be considered for one to be an Indian. Great Arctic Relocation The Great Arctic Relocation occurred in 1950 when cold war was in progress. During this period, the government of Canada moved the indigenous families especially Inuit From northern Quebec to Grise Fjord and Resolute Bay. These families faced challenges since they were not provided with proper basic needs like shelter and food because of ongoing cold in areas of Nunavut. When those families arrived at their respective places, they were forced to separate and without their knowledge before, one group was to live in Grise Fjord while the other group to live in Resolute Bay. Indigenous families were not permitted to move out of those places after arrival since they had been promised so by the government. Footnotes 1. https://www.amnesty.ca/our-work/issues/indigenous-peoples/indigenous-peoples-in-canada 2. https://www.trc.ca/websites/trcinstitution/index.php?p=4 3. https://www.trc.ca/websites/trcinstitution/File/2015/Findings/Calls_to_Action_English2.pdf 4. https://www.thecanadianencyclopedia.ca/en/article/indian-act/ 5. https://www.aadnc-aandc.gc.ca/eng/1100100016115/1100100016116