Taylor Boles
010733995
Ethers and Ether Synthesis
Ethers are organic compounds characterized by an oxygen. The compounds are bounded by two alkyl or aryl. Ethers look like alcohols and both of these look like water. Within alcohols there is one hydrogen atom replaced of water replaced by alkyl but in ether, hydrogen atoms are replaced by alkyl or aryl groups. Ethers are usually nice-smelling and colorless when they are room temperature. Compared to alcohols ethers are less dense and soluble and usually have lower boiling points. Ethers are usually unreactive and so most times they can be useful as solvents. The solvents are waxes, oils, fats, perfumes, resins, dyes, hydrocarbons and gums. Ethers play an important role in medicine and pharmacology.
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Development of specific ethers has been inactive and fruitful area of investigation in the past few decades.2The strategy of ether catalysis General encompasses synergistic activation of a ethers an electrophile by two or more reactive centers through the combination of a Lewis acid and Lewis base working in concert. Such approach results in high reaction rates and excellent ethers. Hydrogen bonding plays a crucial role in this catalysis. Hydrogen bonding to an electrophile decreases the electron density of this species, activating it toward nucleophilic attack. Recently chemists have begun to appreciate the tremendous potential offered by hydrogen bonding as a tool for electrophile activation in synthetic catalytic systems. In particular, ethers donors have emerged as a broadly applicable class of catalysts for ethers synthesis. An amide unit, the key functional group of peptides, plays an important role in catalyst design and modification. Based on the understanding of different asymmetric catalytic reaction mechanisms, the creation of amide structure-based ether and was realized by rational arrangement of hydrogen-bond networks. According to their model, two water molecules simultaneously establish H-bonds to the carbonyl oxygen of the substrate for optimal transition state stabilization. The concept of explicit double H-bonding activation was no longer restricted to one type of reaction or catalyst, but became a generally applicable principle. The simultaneous donation of two hydrogen bonds has proven to be a highly successful strategy for electrophile activation. Such interactions benefit from increased strength and directionality compared to a single hydrogen bond. Ethers containing double hydrogen bond ethers are capable of directing the assembly of molecules with similar control as
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and a ylide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base) 4 An example is benzyltriphenylphosphonium chloride which was used in this experiment. The second step in the formation of the of the Wittig reagent which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1. The positive charge on the phosphorus atom is a strong EWG (electron-withdrawing group), which will trigger the adjacent carbon as a weak acid 5 Very strong bases are required for deprotonation such as an alkyl lithium however in this experiment 50% sodium hydroxide was used as reiterated. Lastly, the reaction between ylide and aldehyde/ketone produces an alkene.3
In this lab 4-tert-butylcyclohexanone is reduced by sodium borohydride (NaBH4) to produce the cis and trans isomers of 4-tert-butylcyclohexanol. Since the starting material is a ketone, NaBH4 is strong enough to perform a reduction and lithium aluminum hydride is not needed. NaBH4 can attack the carbonyl group at an equatorial (cis) or axial (trans) position, making this reaction stereoselective. After the ketone is reduced by the metal-hydride, hydrochloric acid adds a proton to the negatively charged oxygen to make a hydroxyl group. The trans isomer is more abundant than the cis based on the results found in the experiment and the fact that the trans isomer is more stable; due to having the largest functional groups in equatorial positions.
electrophile (electron pair acceptor) with an attached leaving group. This experiment was a Williamson ether synthesis usually SN2, with an alkoxide and an alkyl halide. Conditions are favored with a strong nucleophile, good leaving group, and a polar aprotic solvent.
The most classic and standard procedure for producing esters is the Fisher-esterification reaction. Discovered in 1895 by German chemists Emil Fischer and Arthur Speier 4, this reaction involves refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. In order to drive the equilibrium towards the products, the water from the dehydration process must be removed and there must be an excess amount of alcohol. A vast range of carboxylic acids may be used for this reaction however the type of alcohols are limited. Primary and secondary alcohols are most frequently used in esterification reactions, tertiary alcohols are steric ally hindered usually resulting in poor yields5 and tend to undergo elimination reactions instead. In this rea...
People have often pondered the reasons for the greatness of Edith Wharton's novel, Ethan Frome. What is it that causes this story to be considered an all-time American classic? One journalist quotes a humanities professor at MIT who states that, "We turn to Wharton because the truths she tells are a bracing tonic in a culture steeped in saccharine sentimentality." The journalist goes on to describe the typical, "popular" story and how they often have endings where "romantic ideals are magically fulfilled..." There is much more to Ethan Frome than simply an unhappy ending to contrast with the many other stories that have sugar-coated and sanguine endings. At first glance, the ending of Ethan Frome may appear to be only depressing. In truth, Wharton offers the reader a complex ending through the careful incorporation of poetic justice and irony.
The three butene products have been verified to elute in the following order: 1-butene, trans-2-butene, and cis-2-butene. Theory: The dehydration of 2-butanol, a secondary alcohol, progresses readily in the presence of a strong acid like concentrated sulfuric acid (H2SO4). The reaction is completed via the E1 mechanism. Initially, the hydroxyl group is a poor leaving group, but that is remedied by its protonation by the acid catalyst (H2SO4) converting it to a better leaving group, H2O. The loss of this water molecule results in a secondary carbocation intermediate that continues to form an alkene in an E1 elimination.
It is a clear and colorless liquid with a profound odor. Ethanol is used as a beverage; whether the drink is beer, wine or hard liquor, it is a liquid drug that slows down the central nervous system just like a sedative. Ethyl alcohol is actually classified as a food because it has calories, although it does not have any nutritional value therefore the calories are measured as empty calories. Ethanol is not digested or transported to the bodies’ cells like the normal digestive process; instead it is absorbed directly into the blood stream. Alcohol travels throughout the body by diluting itself in the water already present in the organ systems. Most vital organs, such as the brain, need a large amount of water and blood to function and are particularly vulnerable to the effects of ethyl alcohol. Other than being used as a beverage, ethyl alcohol can be used to clean surfaces from micro organisms, for that reason, one can presume it is toxic to the
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
ISO THANE EMA elastomeric membrane is a liquid applied coating based on urethane perpolymers which cure by reaction with atmospheric moisture to give a continuous film which is elastic. It contains leafing aluminium which gives execellent U.V. resistance.
Alcohol chemically is any organic molecule with an OH functional group, however for the sake of this essay the term alcohol will refer to ethanol, the type of alcohol used in regular consumption. Ethanol is a by-product of yeast (a type of micro-organism). Yeast consume glucose, sugars, from fruits or crops such as barley they then excrete carbon dioxide (CO2) and ethanol (C2H5OH or C2H6O) (How is alcohol made?, n.d.). Yeast do this by the presence of the enzyme zymase in their digestive system. The enzyme speeds up the otherwise long process of glucose break down into carbon dioxide and ethanol, fermentation. This can be represented by the chemical formula:
Since water contains this unique makeup, it is often considered a universal solvent. Different substances from sugar, to salt, and also to acids such as vinegar are able to be dissolved in water. Oils and fats are not able to be dissolved in water because they have no charge and the water molecule is more attracted to itself than the fat and so it will pool to one area. Another of the interesting properties of water is that it contains a high specific heat.
...ginal ingredient may not be available. For example, methyl trans-cinnamate (strawberry), isoamyl acetate (banana), and ethyl butyrate (pineapples) make the perfect flavors for a tropical smoothie! Secondly, esters are found naturally within certain organisms to release scents that alert members of the fellow species or for mating purposes. One example is the Z)-6-dodecen-4-olide, which is a circular ester that releases as a “social scent” for black-tailed deers. Thirdly, esters can also be used in the medical field. For instance, benzocaine is a type of ester used in skin medication to relieve skin burns. Another example is the jojoba ester, which is used in cosmetic products like lotion to soften skin. Fourthly, esters can be used as construction materials. For example, plexiglas is a type of ester used in shatterproof glass replacements and hockey rink barriers.
J. Clayden, N. Greeves, S. Warren, P. Wothers. Organic Chemistry. 8th ed. 2007, Oxford University Press, p. 1186-1191.
Since the first synthetic path for the formation of porphyrins was reported in the 1930s by Fisher1 and Rothemund2 simultaneously, extensive studies regarding coordination, polymerization and porphyrin modifications in the meso and β positions have been reported. These gives a lot of room to tailor the porphyrins so that they feature the desired properties. Porphyrins drawn the attention of scientist in many fields: artificial enzymes, catalytic reactions, organic photovoltaics and molecular electronics.
Cellular Respiration is “the oxidation of organic compounds that occurs within cells, producing energy for cellular processes” (Mander and Windelspecht 2017). All cells need energy. One thing is for sure any cellular processes use enzymes to speed up the reaction. Enzymes are a catalyst used to help speed up chemical reactions because it bonds with the reactant at the activation cite. Enzymes help speed up chemical reactions because they reduce the amount of activation energy and bind with the substrate at the activation site in which is needed in a chemical reaction. The “activation energy that must be added to cause molecules to react with another is energy of activation” (Mander and Windelspecht 2017). Enzymes must be activated by an external