The Nitration Of Methyl Benzoate Biology Essay

The Nitration Of Methyl Benzoate Biology Essay Methyl Benzoate is electron rich and thus undergoes electrophilic aromatic substitution. Nitration of methyl benzoate will form a major product, methyl m-nitrobenzoate that was further purified by re-crystallization. The electrophile or the nitronium ion attached to the meta position in the benzene ring because of the carboxyl group being meta-deactivator that made the reaction took place in the meta position and the ortho and para positions are destabilized. The mass of re-crystallized methyl m-nitrobenzoate was determined to be 0.257 g compared to the mass of methyl benzoate, 0.360 g that resulted to †¦Ã¢â‚¬ ¦ % yield. The melting point of the methyl m-nitrobenzoate resulted to 74 °C compared to its true melting point 78 °C was computed to have 5.13% difference. Many side-products like different orientations in the benzene ring will be formed during chemical reactions. To see how much were formed and how pure was the product was, its TLC Profile was calculated that resulte d into Rf = 0.79 wherein the result from iodine vapor indicating that the product synthesized was pure. The results of the experiment are therefore accurate and useful in familiarizing with reactions and mechanisms that occur during nitration. __________________________________________________________________________ INTRODUCTION Aromatic hydrocarbons are compounds with one or more benzene rings (3). Due to electron delocalization by its alternating double bonds, it is characterized by being more stable compared to alkenes (2). Benzene, being aromatic, is a cyclic compound, an unsaturated compound due the presence of pi bonds. In contrast to the double bonds causing the unsaturation of benzene, it is strong and unreactive because of its resonance structure where there is rearrangement of electron pair. They undergo EAS or Electrophilic Aromatic Substitution reaction due to the fact that they are electron rich. The nitration of methyl benzoate, C6H8O2, undergoes such type of reaction with concentrated nitric acid and sulfuric acid to yield methyl m-nitrobenzoate. From the methyl benzoate, methyl m-nitrobenzoate will be formed and will undergo purification by re-crystallizing with methanol. Thin Layer Chromatography profile and melting point of the product were used in the experiment to make sure that there are no by-products formed like compounds with o- and p- orientation (2). MATERIALS AND METHODS The mass of conical flask was determined and added with 20 drops of methyl benzoate. The mass was also determined as well as the mass of methyl benzoate itself. The methyl benzoate in the flask was placed in an ice bath while added by 2 ml of conc. H2SO4 while swirling. Then, the nitrating agent was prepared which is a mixture of 1 ml conc. HNO3 and 1 ml conc. H2SO4 chilled in an ice bath. The nitrating agent was then added to the methyl benzoate solution using a Pasteur pipet. The mixture was constantly stirred and still chilled in an ice bath. However, conc. H2SO4 must be added if cloudiness occurs to change the mixture into its clear appearance. Furthermore, the reaction mixture was added 10 g of crushed ice then stirred. As the ice melted, the solid product formed was separated using vacuum filtration where a filter paper was folded into 1/16 big enough to cover holes in the Buchner funnel. Then, the product was washed with cold distilled water, followed by 5% NaHCO3 and with col d distilled water until the filtrate became neutral. The product was transferred in a watch glass and dried over a steam bath. Methanol was used to recrystallize or solidify the product and the percentage yield was calculated. The melting point of the recrystallized product was determined using the melting point apparatus. The TLC profile was determined using a TLC plate. The TLC plate was drawn with a line using a pencil 1 cm from the bottom and from the top then dipped in a beaker with ethyl acetate. The plate was dipped in ethyl acetate 3 times. When the solvent reached the other edge (the other line), the plate was removed from the beaker. Lastly, Iodine pellets were used to further determine the TLC profile. RESULTS AND DISCUSSIONS Methyl benzoate, C6H8O2, is an aromatic hydrocarbon, a methyl ester with a colorless appearance and used in perfumery. With Methyl benzoate, methyl m-nitrobenzoate will be synthesized and will further be purified by re-crystallization (2) with results shown in Table 1. Table 1. Percentage Yield of methyl m-nitrobenzoate Mass of conical flask 91.749 g Mass of methyl benzoate and conical flask 92.109 g Mass of methyl benzoate 0.360 g Mass of re-crystallized methyl m-nitrobenzoate 0.257 g % yield The mass of methyl benzoate was determined by difference then cooled in an ice bath then added conc. H2SO4. The solution will still be colorless because methyl benzoate is soluble in H2SO4. Thus, it will form a homogenous mixture. On the contrary, it will form a yellow solution if the flask used is contaminated. The nitrating agent prepared in an ice bath because nitration is an exothermic that requires only 15 °C and must not increase (1). HNO3 and H2SO4 should be added in the homogenous solution slowly while stirring to avoid side products formation like compounds with o- and p- orientation. Also, it will result to a low yield of the product desired. Likewise, fast addition will result to getting a high temperature that must be 15 °C only. Addition of H2SO4 if cloudiness will occur is important since methyl benzoate is soluble in sulfuric acid and will produce a colorless solution. The mixture of HNO3 and H2SO4 produces nitronium ion that will attach to the benzene ring (5). Methyl Benzoate is characterized for being electron rich and thus capable of reacting to electrophiles and undergoes EAS or Electrophilic Aromatic Substitution with a mechanism via carbocation [C+] intermediate shown in Figure 1. Figure 1. Complete Mechanism of Nitration via Carbocation Intermediate It follows 3 steps that started from the generation of electrophile which is the nitronium ion, NO2. Then, the formation of carbocation intermediate where nitronium ion will be attacked by the nucleophile will follow. The carbocation in the second step is capable of resonating since aromatic compounds are resonance structure wherein the electron pair can move around the molecule. The resonance of the benzene ring makes them stable and favorable to the reaction since the more stabilize the benzene ring is, the more reaction. The last step is the dissociation of H+ and the reformation of aromatic ring where the electrophile will substitute in one of the hydrogens on the benzene ring. This mechanism resulted to an overall reaction shown in Figure 2. Figure 1. Nitration of methyl benzoate The solvent of the nitration which is the sulfuric acid will protonate the reagent, methyl benzoate, which will create stabilized carbocation intermediate. The electrophile or the electron poor nitronium ion, will react to the protonated intermediate in the meta position. The carboxyl group belongs to the e- withdrawing group that deactivates the aromatic ring. Since electron withdrawing group has a meta orientation and a deactivator, the reaction will take place in the meta position. Likewise, the ortho and para positions are destabilized (5). The major product now is the methyl m-nitrobenzene which has nitro and carboxyl group being both electron withdrawing groups oriented at the meta position. After adding the nitrating agent, the reaction mixture was added 10 g of crushed ice until it solidified and filtrated by vacuum filtration to get a dryer product. It was then washed by cold distilled water and 5% NaHCO to make excess acid neutralize that made the product green-colored. The product was dried over a steam bath and re-crystallized with methanol for purification. By washing the product with methanol, by-products or impurities like substitution on different places on the aromatic ring (ortho and para positions), methyl-2-nitrobenzoate or maybe methy-3-nitrobenzoate formed during the previous reactions should purified to get the preferred product. However, the methanol is preferred cold to control loss of desired product. The re-crystallized methyl m-nitrobenzoate weighed 0.257 and had †¦Ã¢â‚¬ ¦ % yield. The melting point of the re-crystallized methyl m-nitrobenzoate was determined to be 74 °C that is close to its true melting point being 78 °C. The % difference was determined to be 5.13% as shown in Table 2. Table 2. Melting point of re-crystallized methyl m-nitrobenzoate Melting point of re-crystallized methyl m-nitrobenzoate 74 °C True Melting point of methyl m-nitrobenzoate 78 °C % difference 5.13% To see how much products were formed and to check its purity, the TLC profile or Thin Layer Chromatography should be done (6). Each trial as the TLC plate was dipped in the solvent (Ethyl acetate) should have only 1 spot that is equivalent to 1 compound. If 3 spots were formed in the TLC plate on 3 trials when the solvent moves on the top of the plate by capillary action, it simply means that 3 compounds were present in the product. Thus, making it considered as not pure. The spots will be clealy visualized when the plate is placed in an iodine vapor (4) here it sublimes from solid to liquid stain. Also, other compounds are capable of adsorbing iodine and become visible. On the contrary, the re-crystallized m-nitrobenzene formed had been considered as a pure compound as illustrated in Figure 3 and had an Rf value of 0.79. Rf = dspot / dsolvent front Rf = 3.75 cm / 4.6 cmC:Documents and SettingsnicolleMy DocumentsCollege Files2nd Year 2nd SemORGCHEMLABEXPT4 NITRATION OF METHYL BENZOATETLC Plate.jpg Rf = 0.79 dsolvent front = 4.7 cm dspot = 3.7 cm Figure 3. TLC Profile The desired product, methyl m-benzoate, purified by re-crystallization was successfully synthesized from methyl benzoate by avoiding the formation of other side-products. However, if phenyl benzoate was used, it will also follow EAS or Electrophilic Aromatic Substitution

Metafiction and Happy Endings (Margaret Atwood) Essay

A. Definition: The narrator of a metafictional work will call attention to the writing process itself. The reader is never to forget that what she is reading is constructed–not natural, not â€Å"real.† She is never to get â€Å"lost† in the story. B. Possible Contents: intruding to comment on writing involving his or herself with fictional characters directly addressing the reader openly questioning how narrative assumptions and conventions transform and filter reality, trying to ultimately prove that no singular truths or meanings exist C. General Characteristics Metafiction often employs intertextual references and allusions by: examining fictional systems; incorporating aspects of both theory and criticism; creating biographies of imaginary writers; presenting and discussing fictional works of an imaginary character. Authors of metafiction often violate narrative levels by: intruding to comment on writing; involving his or herself with fictional characters; directly addressing the reader; openly questioning how narrative assumptions and conventions transform and filter reality, trying to ultimately prove that no singular truths or meanings exist Metafiction also uses unconventional and experimental techniques by: rejecting conventional plot; refusing to attempt to become â€Å"real life†; subverting conventions to transform reality into a highly suspect concept; flaunting and exaggerating foundations of their instability; displaying reflexivity (the dimension present in all literary texts and also central to all literary analysis, a function which enables the reader to understand the processes by which he or she reads the world as a text). It also poses questions about the relationship between fiction and reality by drawing attention to its characteristic as an artifact by itself. No sense of reality in its entire spectrum as a genre even though the extremes of each end are minute acceptance and merely exploration of fictionality to the other end being utter denial of reality itself. D. Examples: Adams, Douglas. The Hitchhiker’s Guide to the Galaxy. 1979. Mitchell, David. Cloud Atlas. 2004. HAPPY ENDINGS A. Characters: The author uses common names for the characters which allows him the versatility of putting them into different situations. Doing so supports the way the author puts much importance on what happens during the story instead of how it ends. John one of the most common boy names, has ranged from musicians (John Lennon), to leaders (John F Kennedy), to philosophers (John Locke) etc. This can emphasize the author’s use of putting the character into different contexts, changing the plot and how he plays different roles, yet emphasizes that it all ends the same (death). -Idea that the ending of a story is always the same, but only the middle matters In the story he is a loving husband, adulterous partner, womanizer Mary meaning of the name Mary is: Wished-for child; rebellion; bitter. Famous Bearers: the Virgin Mary; Mary Magdalene; Mary, Queen of Scots. Also shows how the author putes his characters in different situations. James -minor character Fred – minor character Madge – minor character B. Setting: The author employs the use of place as setting in the story. Various examples of setting seen in the story are an apartment, as seen in story B, and a â€Å"charming house,† as seen in story A, C and As seen in the line, â€Å"Remember, this is Canada. You’ll still end up with A, though in between you may get a lustful brawling saga of passionate involvement, a chronicle of our times, sort of,† the setting of the story and each of its segments is a medium for what each character does before he reaches the end. The setting of the story could have an influence on what one could do before he dies, the end which everyone eventually reaches. This is seen in the story wherein each segment (letters) had different bodies of story, yet everything â€Å"continues as in A† in which the characters live on with their lives then die. D. Concepts: Ex: How do elements in the story help to create meaning? Like: setting, tone, imagery, symbol, irony, etc Metafiction in Happy Endings The author tackles the â€Å"What?† question in the writing process through his story Happy Endings. He goes through many scenarios but shows us that the conclusion to each scenario is the same. The question â€Å"What?† only leads to the ending of the story which we already know will be the same. The important things to ask rather are â€Å"How?† and â€Å"Why?†. These questions make up the middle of the story, the events that happen, the part that counts. Textual Irony Title is Happy Endings but the real endings are al the same and result in death Conflict Is always changing depending on the situation given. Always has something to with the subject of love. SYMBOLS E. Title â€Å"Happy Endings† Most people usually focus on the ending of a story Everyone wants a happy ending, but in reality we all meet an equal end which is that we eventually die There is no such thing as a happy ending. All are the same in which we all eventually pass away. What matters is what is done as we reach the end. F. Theme What matters the most in the story is not the ending, but what what we do on the way there, because we can change our situations by choosing to act in the present, but not matter what you do you can’t change your inevitable end. RANDOM NOTES Margaret Atwood’s Happy Endings is an illustration of the idea that the ending of a story is always the same, but only the middle matters. And Love plays an important factor in all scenarios. SYNOPSIS: It includes six stories in one, each ending with death. The author believes that this is the only sure ending to anything. The stories are all inter-related, containing the same characters and similar actions. Behind the obvious meaning of these seemingly pointless stories lies a deeper and more profound meaning†¦. What is the common denominator between all these scenarios? In case you missed it, Atwood sums it up in her concluding remarks. ‘John and Mary die. John and Mary die. John and Mary die.’ ‘ Happy Endings’ forces us to question the point of life. Every story, carried to its ultimate logical conclusion, has the same ending, because all lives have the same ending. We may die in the heat of battle; we may die in our sleep. We may die in infancy, in a gang war, in a nursing home. But we’re going to die. The story isn’t in the ending — it’s in what we do on the way there. RESOURCES USED http://ronosaurusrex.com/metablog/list-of-metafictional-works/ http://www.geneseo.edu/~johannes/Metafiction.html http://postcolonialstudies.emory.edu/metafiction/#ixzz2e1Z087Wr http://www.storybites.com/book-reviews/happy-endings-by-margaret-atwood.php characters http://www.bookrags.com/studyguide-happyendings/char.html themes http://www.bookrags.com/studyguide-happyendings/themes.html (online copy: http://web.ics.purdue.edu/~rebeccal/lit/238f11/pdfs/HappyEndings_Atwood.pdf ) View as multi-pages

Comparing Colonial Virginia and Colonial New Englands...

I believe colonial New England had more of an effect on the American character than Virginia for several reasons. First they promoted more of the values that have transcended into modern day America such as religious toleration, their educational ideas and their focus on the importance of family. And we shouldn’t forget the fact that the American Revolution began in New England so in essence the America we know today would not exist without New England. First off, colonial New England was more family based, as I believe America is today. When immigrants landed in New England they brought with them their families, expecting this place to become their permanent place of residence. Therefore their communities were more tight nit and†¦show more content†¦Second, the New England colonies were founded by many who were seeking religious freedom, therefore the New England colonies were more open minded regarding religion. For instance, the first religious toleration act was passed in Maryland in 1649 by the by the assembly of the Province of Maryland. This act mandated religious toleration. Rhode Island was also seen as a colony of free thinkers and a place for religious toleration. So there was simply a lot of diversity in New England, the vast majority were Protestant Christians however there were significant numbers of Roman Catholics in Maryland and Delaware, as well as a small amount of Jews, most of which lived in R hode Island. So therefore it was New England that began acting upon one of this country’s founding ideals, the ideal of freedom of religion. Our system of education is still based of a lot of colonial New England’s system of education. The first public schools of the new world began in New England with the passing of what is referred to as the Olde Deluder Satan Act which â€Å"specified that schools be started and publicly supported when town populations were large enough.† So basically they would build a school if the population of a particular are became large enough and the demand from the local citizenship was high enough. Whereas those in the Virginia area’s of the new world were either home schooled (often poorly) or immediatelyShow MoreRelatedBoyer Dbq Teacher Guide10764 Words   |  44 Pagesorganization. Each of these can be considered in turn with outside information from the student’s course and examples drawn from the documents. These include references to Spanish and French colonial efforts as well as to both the New England and Chesapeake colonies of England. Most students will probably conclude that England’s efforts were most successful, though students should not be penalized for other conclusions, provided that they provide a persuasive rationale. Note the limits of the question in terms

Disaster Warnings For The Deaf And Hard Of Hearing

Accessibility of Disaster Warnings for the Deaf and Hard of Hearing In the event of natural disasters like hurricanes, the benefit of warning and preparedness measures cannot be underscored. Alert systems and pagers provide citizens crucial seconds to seek a safe location. Additionally, they can provide important updates on event related weather conditions, road conditions, and evacuation notices.Such information is also often dispersed through televised government proceedings and radio programming. While these measures have been demonstrated to save lives and prevent injuries, for the nearly forty million Americans who identify as Deaf and Hard of Hearing these warning systems pose a barrier to their access of crucial information (Ivey†¦show more content†¦The main sources of destruction for these storms are wind speeds in excess of 74 mph, storm surges, and floodwaters several feet deep (Havelock, 2016). For people in the path of these incredibly dangerous storms, the most crucial action to be taken is evacuation (Havelock, 2016). Unfortun ately, as was seen in the case of Hurricane Katrina it is quite common in response to the threat of a hurricane for those most at risk to not heed warnings and to stay in unnecessarily risky situations (Demuth et al., 2012, p.1133) When Hurricane Katrina hit in 2005 there was a clear disconnect in how the needs of the deaf were being handled. There are several personal reports of the events that provide evidence for accessibility inadequacies. In a report by deaf social worker Barbara White, she describes how the community struggled for their needs to be understood (White, 2014 p.4). One of the biggest issues was the resistance of government officials to allow people with ASL and deaf studies training to be set down to relief areas because â€Å"they did not feel there was a ‘significant’ need† (White, 2014, p.1-2). After a continued push White was able to set out for the hard hit south but the delay had already meant that deaf people were being left to decipher media reports in an inaccessible modality. She goes on to describe how this had a continued impact in the evacuee shelters. Though the majority of evacuees used ASL there were