Diels-Alder Reactions Experiment

Diels-Alder Reactions Experiment Abstract A Diels Alder reaction was done during this experiment between anthracene and maleic anhydride via to yield 9, 10-dihydroanthracene-9, 10-ÃŽÂ ±, ÃŽÂ ²-succinic anhydride. Anthracene was the diene and maleic anhydride was the dienophile. Following recrystallization of the product using xylene and vacuum filtration, a percent yield of 39.9% was calculated for the recrystallized product that was collected. The yield may have been low due to several of the crystals being stuck to flask and not going into the funnel, and there may have been other sources of error. The percent recovery from recrystallization was 56%. The melting point of the recrystallized product was 260 264 °C, while the literature melting point of 262 264 °C. Comparing these values shows that the product was indeed and that recrystallization yielded a purer product. Upon examination of an infrared spectrum of the product and of anthracene and maleic anhydride spectra, the data showed that the product spectru m had similarities with both spectrums for anthracene and the maleic anhydride. This indicated that 9, 10-dihydroanthracene-9, 10-ÃŽÂ ±, ÃŽÂ ²-succinic anhydride was a product of both anthracene and maleic anhydride, and thus that the experiment was successful. Figure 1: Reaction scheme of 9,10 dihydroanthracene-9, 10- ÃŽÂ ±, ß-succinic anhydride Introduction The 1950, Otto Paul Hermann Diels and Kurt Alder were awarded Nobel Prize in chemistry for their work on the discovery and development of [4+2] cycloaddition reactions. Diels-Alder reactions are used to synthesize new carbon-carbon bonds, more commonly they form six-membered cyclic compounds. The Diels-Alder reaction is categorized as a pericyclic reaction, which involves the overlap of spatial orbitals as well as the hybridization and delocalization of the molecules.1 The Diels-Alder reaction is a member of a class of reactions called cycloadditions, which are under pericyclic reactions. Usually, the reaction involves three à Ã¢â€š ¬ bonds, two from the diene and one from the dienophile in the reaction to form a six-membered ring.Since this reaction involves four à Ã¢â€š ¬ electrons in the diene and two à Ã¢â€š ¬ electrons from the dienophile, it is sometimes referred to as a 4à Ã¢â€š ¬ + 2à Ã¢â€š ¬ cycloaddition. Various chiral auxiliaries and catalysts for asymmetric Die ls-Alder chemistry have been developed that allow the cycloaddition to proceed with very high levels of selectivity.3 The use of chiral Lewis acid catalysts and high pressure to enhance the selectivity and rate of these [4à Ã¢â€š ¬ + 2à Ã¢â€š ¬]-cycloadditions have further extended the scope of this remarkable reaction.1,2 Diels-Alder reactions are normally favored by electron donating groups on the diene and electron withdrawing groups on the dienophile. The diene must be able to achieve a s-cis conformation to generate the cis double bond in the cyclohexene product.3 Acyclic dienes may rotate around a single bond, but dienes locked in the s-trans conformation do not react.3 The purpose of this experiment is to yield 9,10-dihydroanthracene-9,10-ÃŽÂ ±, ÃŽÂ ²-succinic anhydride via a Diels Alder reaction between anthracene and maleic anhydride, as shown in figure 1. Anthracene acts as the diene and maleic anhydride functions as the dienophile. Xylene is used as a high boili ng temperature solvent so that the reaction will proceed quickly. A key characteristic of these reactions is their stereospecificity.3 Based on the interaction between a cyclic diene and a dienophile, different stereoisomeric compounds are formed. Stereochemistry represents a major component of the Diels-Alder reaction.2 Due to the interaction and arrangement between the conjugated diene and dienophile, an endo and exo product could be formed, which can characterize the reaction as stereo- and/or regioselective. Experimental Instruments used: The instruments that were used were the Thomas Hoover Melting, and a Nicolet IR 100 FT-IR were used in this experiment. Procedure and Observations: A reflux apparatus was assembled. Xylene (6 mL), anthracene (0.5 g), and maleic anhydride (0.25 g) were added to a round bottom flask (25 mL). The solution turned a yellow color when the reactants were added together. The reflux was then started, and once it began to boil, it was boiled for 30 minutes. A watch glass was weighed (35.55 g), which the product would later be transferred to. After reflux, the solution was cooled to room temperature, and then xylene (6 mL) was added to a test tube and laced into an ice bath. The solution appeared to be a golden yellow color after the reflux. Next, xylene (15 mL) was added to a beaker (50 mL), and then a vacuum apparatus was assembled. The solution was placed chilled for 5 minutes, and it became cloudy and crystals began to form. The solution was filtered through a Buchner funnel on the vacuum filtration. After the vacuum filtration, the crude product were light yellowish-brown crystals. Xylene (15 mL) was boiled , and was then added to the crude product, just enough to cover it, and was heated. The crystals began to dissolve the hot xylene was added, and as it dissolved the color became lighter and clearer. Once dissolved, the solution was then placed into an ice bath, after being cooled to room temperature. It was then put through the vacuum filtration; the recrystallized product was allowed to dry, and then weighed (0.28 g). Finally, the product was analyzed using IR and the melting point apparatus. References C. Oliver Kappe, S. Shaun Murphree, Albert Padwa, Synthetic applications of furan Diels-Alder chemistry, Tetrahedron, Volume 53, Issue 42, 1997, Pages 14179-14233, ISSN 0040-4020. Wade, L.G., Jr. The Diels-Alder Reaction of Anthracene and Maleic Anhydride (1998). Simek, Jan William., and L. G. Wade. Solutions Manual Organic Chemistry, Eighth Edition L.G. Wade, Jr. Boston: Pearson, Boston, 2013. Print.

Hydrogen Essays -- essays research papers

Since the beginning of the scientific revolution in the early nineties the mankind looks for an energy source that is clean and renewable; solution of this problem would be probably the most common thing in our life - WATER. Water consists of two chemical elements, hydrogen and oxygen. Each molecule of water consists of two hydrogen (H2) atoms and one oxygen (O) atom. Chemical binding between these three atoms is very stable and strong. Therefore, the reaction of hydrogen and oxygen is under normal circumstances very intense and generates a lot of energy. 2H2 + O2 Â ® 2H2O + energy Both, hydrogen and oxygen are gases at normal temperatures and pressures and the product of this reaction is pure water, usually in its gaseous form - steam. Now it may look like hydrogen is the ideal power source that mankind is ever since looking for. More than 70 % of the Earth surface is covered by water, therefore hydrogen is renewable and unlimited. Reaction of hydrogen with oxygen generates a lot of energy and it does not have any negative output, only water. But, the respectable power hidden in water is known for more than 200 hundred years and as long scientists are trying to find a way to extract this energy, rather how to split the water molecules into hydrogen and oxygen. Hydrogen can be used to power cars, rail engines, airplanes, to produce electricity and heat. But, although the technical breakthrough in 19th and 20th century brought hydrogen into experimental use in many applications, there are still many problems to deal with. There sure is a lot of misinformation about hydrogen gone to public, so here are the basic facts about hydrogen as a power source according to the Nuts & Volts Magazine. Hydrogen on earth is not a fuel. It is only an energy carrier. Following the definition of the word fuel, fuel is a substance that is capable of delivering new energy when burning or other chemical reaction occurs. On the other hand energy carrier is a substance that is only able to move previously acquired energy from one place to another. To be accurate, water molecule is energetically very advantageous for both oxygen and hydrogen atoms and needs much energy to disintegrate it again into hydrogen and oxygen atoms, or better H2 and O2 molecules, therefore H2 and O... ...national strength of all the countries that do not have any important petroleum resources and every country could be self- sufficient with hydrogen. For example U. S. trade balance sheets show that oil imports drain 1 billion dollars from the U. S. economy every week. Important is also the "clean transport effect", thanks to an engine that does not produces any carbon dioxide or other environmentally dangerous emissions. Hydrogen could be considered to be more safe than gasoline, if safety prescriptions are not violated, in case of an accident hydrogen would quickly evaporate and ascend in the atmosphere, while gasoline would stay spilled on the ground. Hydrogen caries much more energy than gasoline, is more engine saving and also the fuel cell technology promises further development and increasing reliability of hydrogen powered cars. Following United States Department of Energy we can expect regular hydrogen-powered traffic in 20 maybe 30 years. Although, until now no hydrogen-powered cars are in production and hydrogen-powered engine is only under development hydrogen stays the main alternative fuel of the future. Hydrogen Essays -- essays research papers Since the beginning of the scientific revolution in the early nineties the mankind looks for an energy source that is clean and renewable; solution of this problem would be probably the most common thing in our life - WATER. Water consists of two chemical elements, hydrogen and oxygen. Each molecule of water consists of two hydrogen (H2) atoms and one oxygen (O) atom. Chemical binding between these three atoms is very stable and strong. Therefore, the reaction of hydrogen and oxygen is under normal circumstances very intense and generates a lot of energy. 2H2 + O2 Â ® 2H2O + energy Both, hydrogen and oxygen are gases at normal temperatures and pressures and the product of this reaction is pure water, usually in its gaseous form - steam. Now it may look like hydrogen is the ideal power source that mankind is ever since looking for. More than 70 % of the Earth surface is covered by water, therefore hydrogen is renewable and unlimited. Reaction of hydrogen with oxygen generates a lot of energy and it does not have any negative output, only water. But, the respectable power hidden in water is known for more than 200 hundred years and as long scientists are trying to find a way to extract this energy, rather how to split the water molecules into hydrogen and oxygen. Hydrogen can be used to power cars, rail engines, airplanes, to produce electricity and heat. But, although the technical breakthrough in 19th and 20th century brought hydrogen into experimental use in many applications, there are still many problems to deal with. There sure is a lot of misinformation about hydrogen gone to public, so here are the basic facts about hydrogen as a power source according to the Nuts & Volts Magazine. Hydrogen on earth is not a fuel. It is only an energy carrier. Following the definition of the word fuel, fuel is a substance that is capable of delivering new energy when burning or other chemical reaction occurs. On the other hand energy carrier is a substance that is only able to move previously acquired energy from one place to another. To be accurate, water molecule is energetically very advantageous for both oxygen and hydrogen atoms and needs much energy to disintegrate it again into hydrogen and oxygen atoms, or better H2 and O2 molecules, therefore H2 and O... ...national strength of all the countries that do not have any important petroleum resources and every country could be self- sufficient with hydrogen. For example U. S. trade balance sheets show that oil imports drain 1 billion dollars from the U. S. economy every week. Important is also the "clean transport effect", thanks to an engine that does not produces any carbon dioxide or other environmentally dangerous emissions. Hydrogen could be considered to be more safe than gasoline, if safety prescriptions are not violated, in case of an accident hydrogen would quickly evaporate and ascend in the atmosphere, while gasoline would stay spilled on the ground. Hydrogen caries much more energy than gasoline, is more engine saving and also the fuel cell technology promises further development and increasing reliability of hydrogen powered cars. Following United States Department of Energy we can expect regular hydrogen-powered traffic in 20 maybe 30 years. Although, until now no hydrogen-powered cars are in production and hydrogen-powered engine is only under development hydrogen stays the main alternative fuel of the future.

Fast Changes in Technology- Excitement or Agony Essay

In 1859, Charles Darwin published his theory of natural selection in which he observed that finches adapted a different beak shape to be able to survive in their environment. Science and technology are our civilization’s beak. A very good afternoon to everyone present here today. I, Shimona Agarwal, Of Scottish High International School, will be speaking today on the topic â€Å"Fast changes in science and technology- excitement or agony† and I am resolutely for the motion. As I am sure that most of you are aware, the global population is increasing at an alarming rate. While just a mere 10 years ago, the world population was 6070 billion, it is now a complete 7 billion. This rate of growing population will become unsustainable in the near future unless science and technology are advanced. Advancements in science and technology have provided humankind with luxuries that have enabled them to live a safe and comfortable living. Only, and only through the rapid changes being made in science and technology, have we been able to increase the average life span of a human being. There are new medical breakthroughs occurring every day, and new innovations are helping mankind lead a safer living. A particular idea that is fast advancing and can prove to be extremely useful is that of using EEG to put the brakes on a moving vehicle. This is a big deal because the normal reaction time for a person to apply the brakes is often too long to prevent an accident. However, by harnessing brain signals via electroencephalography (EEG), most accidents can be prevented. With further advancements, it will be soon possible for humankind to avoid death altogether. Stem Cell Heart Regeneration is such a field where science and technology is fast progressing and showing positive results. See more: how to cite an article For the first time, a human heart has been created using stem cells, a major step forward in organ generation. Scientists used adult stem cells to create a living human heart that they hope will revolutionize transplants. If all goes as planned, the heart will continue to grow and eventually begin beating automatically. Advancements in science and technology are the only way to prevent the eventual collapse of our environment. As the climate changes and pollution increases, we are facing a potential decline of our environment. New advancements, however, are providing us with solutions to save our environment. A recently discussed topic is Paperless Paper. For us stubborn paper lovers, there may soon be a product available that provides the look and feel of paper, with the advantages of a digital device. In fact, the technology is already available, though it hasn’t yet translated into a marketable product. It’s called electronic paper. Before long, the plastic shell of e-readers may not be needed and you’ll be able to handle â€Å"paper†. Another innovation which can prove highly helpful to our environmental problems is a space-based dust cloud which can be used to protect our Earth’s atmosphere. Scottish scientists have proposed to use a giant space-based dust cloud, blasted off an asteroid, to shade the Earth from the sun. This dust-cloud could be large enough to block out 6. 58% of solar radiation that would normally reach the Earth. This would be more than enough to combat any current global warming trends. Waste disposal problems are posing a serious threat to our environment and ecosystem, and science and technology could eventually solve this problem too. Using Plasma Arcs for waste disposal is gaining momentum in the waste disposal industry. Imagine harnessing the power of lightning to turn garbage into glass or into a gas that can be used as an energy source. The advantages include less garbage in landfills, less carbon from incineration, and creating a natural gas power resource. As I come to the end of my debate, I would just like everyone present here to truthfully acknowledge the fact, that without science and technology our lives are never complete. We need technology to advance for civilization to advance. At one point the wheel was the hottest piece of technology around.

Making Sense of Since

Making Sense of Since Making Sense of Since Making Sense of Since By Maeve Maddox Sometimes a word that is clear in one context, may create ambiguity in another. Consider the following excerpt from a professional newspaper review of Hotel for Dogs. The story follows 16-year-old Andi (Emma Roberts) and her 11-year-old brother Bruce (Jake T. Austin) who, since the death of their parents, have lived in five foster homes over two years. Each move is challenging as they have to find ways to smuggle their charming Jack Russell terrier Friday, a member of their family since happier times, into each new household. If you havent seen the film, can you tell from this paragraph if the children had the dog before their parents died? Dont study it. Just base your impression on one quick reading. The first time I read it, I thought it meant that theyd had the dog before the parents died, but as I went on with the review, I began to wonder if the children had acquired the dog after being sent into foster care. In both phrases, the word since is a preposition. The OED gives two meanings for since as a preposition: 1. Ever or continuously from (a specified time, etc.) till now. 2. During the period between (a specified time) and now; at some time subsequent to or after. OED In the phrase since the death of their parents, the since marks a specific starting point. In the phrase since happier times, the time period is ambiguous. This since could, like the first since, mark a starting point subsequent to the happy times enjoyed with their parents, or it could indicate an earlier starting point, during the happy times. I havent seen the film, so to figure out the writers intended meaning, I googled (Oh, dear. I made a Google search of) They had a dog named Friday and found this refreshingly unambiguous statement in a review written by a high school senior: When their parents were still alive they had a dog named Friday and after their parents passed away they kept the dog Janeane White Not every reader would have had difficulty with this paragraph, but at least one did. And if one reader stumbles, its likely that others will. To avoid confusion, its probably a good idea for a writer to avoid using the same word twice in the same paragraph, especially words that have more than one meaning, however slight the difference. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Misused Words category, check our popular posts, or choose a related post below:100 Words for Facial ExpressionsSelect vs. SelectedList of Prefixes and Suffixes and their Meanings

Bailouts as a Financial Aid from the US Government

Bailouts as a Financial Aid from the US Government The interference by the US government in order to help large firms or states facing financial crisis is a crucial undertaking because the failure in this regard affects the economy adversely. In this regard, the government promotes measures that channel financial aid to firms or states in need of help. History demonstrates that the US government has participated in bailouts for various American corporations and states. In 1971, the Lockheed Corporation faced numerous financial challenges.Advertising We will write a custom essay sample on Bailouts as a Financial Aid from the US Government specifically for you for only $16.05 $11/page Learn More The anticipated failure of the corporation meant that a large number of people would become jobless. In addition, the corporation’s failure would affect America’s gross national product and its defense system. However, Lockheed could pay off its various debts because of a bailout realized through the Emer gency Loan Guaranteed Act passed by the Congress. In the 1970s, the New York City entered a period characterized by numerous financial problems. In response, the US government provided an estimated $2.3 billion to the city in terms of loans. The New York City Seasonal Financing Act enabled New York to obtain the largely needed financial aid. The 9/11 terrorist attacks in the United States affected the airline industry negatively. Various airlines incurred considerable financial losses due to the mandatory grounding of aircraft because of terrorist attacks. In this regard, the Bush administration passed into law the Air transportation Safety and Stabilization act that introduced various forms of compensation for the affected airlines. The provision of financial assistance to businesses and states presents various opportunities. First, it creates an opportunity that allows the company of concern to remain within the industry to avoid causing any significant effects on other related en tities. Thus, a country may grant subsidies or loans at low rates to a company in order to ensure that all the vital industries continue to function in a manner that promotes the sustenance of the economy. Furthermore, such an approach cushions the economy from various ripple effects whose outcomes are undesirable to a country. In this regard, the government can control unemployment rates and other costs such as welfare expenses due to reduced livelihoods. Bailouts provide companies and states with an opportunity to evaluate various aspects concerning financial management. In this regard, companies or states can adopt policies that promote the effective use of funds, and eliminate policies that increase chances of financial crisis. Furthermore, bailouts provide the government with an opportunity to benefit from loan fees.Advertising Looking for essay on business economics? Let's see if we can help you! Get your first paper with 15% OFF Learn More The advocat es for the free market oppose the intervention by the state on matters relating to the economy. In their opinion, the provision of financial aid to companies or states encourages them to perform poorly. Another consideration among the free market advocates is the government’s influence on the normal functioning of various market forces. The funds utilized to rescue companies or states should go back to the treasury once the bailout beneficiary has regained financially. However, not all the companies or states that receive financial assistance attain full recovery. Some companies become bankrupt leading to the loss of public money. Another challenge is cases of disagreement between various parties involved in the setting up of a bailout program for a certain company or state. For example, although the Penn Central Railroad was in dire need of financial assistance, disagreements between the administration and the Congress led to the eventual failure of the corporation.

Research Topics with Explanation Essay Example | Topics and Well Written Essays - 500 words

Research Topics with Explanation - Essay Example The provision of the maintenance of the group health benefit of the employee, at the time he or she is on leave, is an added advantage in the provisions of the law. A change in the FMLA, therefore, shall serve justice to employees who, given these reasons, need to take leave from their work. The law provides 12 weeks unpaid leave of assured protection of the employee’s job within any given twelve months time (United States Department of Labor, 2010). I chose the topic because among the provisions in the law are issues that relate to health. Health is an invaluable need for every employee should have a job-protected leave to attend to health matters. Given the inevitability of the reasons for the leave, it should be a paid leave. The target audience is the labor department that needs to make considerations of changing the law into paid leave (Perritt, 2004). Standardization of regulations regarding the use of cells phones while driving is an inevitable need for ensuring safety in the transport sector. Drivers of commercial motor vehicles should be subject to restrictions in the use of mobile phones while driving. They should abide bythe provisions by the FMCSA. Failure to comply as per the provisions of the law should attract a new disqualification sanction the drive or the commercial driver’s license upon multiple convictions for violation. Imposing restrictions on drivers of motor vehicle carrier relating to their use of mobile phones while conducting operations in the interstate commerce would further strengthen such regulations (FMCSA, 2010). Safety in the highways would gain improvement with standardization of regulations regarding cell phone use while driving. Driver-related crashes on the highways would reduce significantly. Cases of injuries that involve these drivers would be low (Wyllie, 2007). I chose this topic becaus e of the increasing concern over several lives lost in accidents involving drivers of commercial motor vehicles. The target

Operatint a Successful Restaurant Assignment Example | Topics and Well Written Essays - 1500 words

Operatint a Successful Restaurant - Assignment Example These limits include procedures of delivery, storage and cooking (Alonzo, 2007). Thirdly, critical limits for the critical control points should be determined for every menu item. These limits must be adhered to so as to minimize any possibility of food poisoning. For instance, poultry storage and preparation should meet the appropriate temperature controls. Poultry should be cooked at temperatures above seventy-five degrees Celsius. On the other hand, beef should be cooked at temperatures above one hundred and sixty degree farenheight. Duration of cooking should also be definite so as to ensure appropriate cooking (Dismore, H., & Entrepreneur Press, 2006). Fourthly, the critical control points should regularly be monitored. The restaurant manager should monitor every food handler. They should ensure that appropriate procedures are followed. Fifth, corrective measures for a breach of any steps above shall be recommended. To cater for this, staff members should undergo refresher training on food safety, menu development and ensuring quality service. Corrective action may be necessitated due to various reasons. These reasons include unattractive food, complaints from customer, storage of out of date foods, and sighting of pests and unclean utensils (Alonzo, 2007). Sixth, system verification strategies should be implemented and verified. In adherence to Hazard Analysis and Critical Control Points (HACCPP) standards, the restaurant should ensure that the plan is developed. Availability of thermometers to ensure appropriate temperatures of food items should be ensured. Finally, appropriate record keeping procedures for the staff members would be necessitated. Daily corrective actions applied should be recorded in flow charts accurately. The HACCP demands that every restaurant keep checklists and time and temperature logs. Record keeping shall be considered for every stage in food handling and preparation (Alonzo, 2007). Guidelines