Fluorenene to Fluoronone free essay sample

The goal of the first part of this experiment was to achieve a 50-50 conversion of fluorene to Fluorenone. In order to achieve the goal of the experiment fluorene was oxidized to Fluorenone. The hydroxide ions from the sodium hydroxide in the presence of Stark’s catalyst would be able to de-protonate the acidic fluorene protons. This would result in the formation of a carbanion which attacks the oxygen from the air resulting in the formation of a hydroperoxide and eventually a ketone (after removal of water). Since the goal was to have a mixture of 50% fluorene conversion, Thin Layer Chromatography (TLC) was carried out several times to assess the rate of the reaction. In order to separate the aqueous composites from the solution extraction was carried out where the product was washed several times with Toluene and HCl and NaCl. In order to dry the excess water and obtain a ketone calcium chloride was used as a drying agent. We will write a custom essay sample on Fluorenene to Fluoronone or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The data obtained from TLC showed that the Rf value for the starting material was on a range of 0. 68-0. 75. The Product obtained had varied concentrations of the fluorene and Fluorenone. The average Rf value obtained for the product was 0. 205. Through this data, it can be concluded that the ketone (Fluorenone) was more polar that fluorene. This data is theoretically correct as well since ketons are supposed to be more polar than alkenes due to the presence of C=O bond. However, TLC data showed that the conversion of fluorene was not achieved to a 50-50 level but had proceeded even further, almost to a point where none of the fluorene remained in the solution. This was determined because in the last TLC slide the presence of Fluorenone was little (the dots size was smaller than it should have been). This error served as a basis for more errors in the second part of the experiment. Reason for this error was that the TLC was not carried out sooner than it should have been due to which the rate of reaction was inaccurately monitored. Also the stirrer was left on even during the course of the TLC. This would have also lead to a higher conversion of the reagent. In order to avoid this error, the reaction with air should have been stopped completely, while taking TLC. The mass of the product obtained in the end was about 6. 26 grams. The theoretical yield should have been 0. g. However, the theoretical yield holds true if and only if the reaction went to a 100% completion and contained no impurities. The goal of the second part of the experiment was to separate the fluorene and Fluorenone mixture by the method of column chromatography. Column chromatography was used in this part of the experiment as a separation technique since it permits the sample to be collected whereas TLC only allows the product to be separated and not collected. In the experiment TLC was also used to monitor the effectiveness of the separation. Hence, in preparation of the column, glass fiber was first filled into the column followed by sand, after which 3† alumina was filled into the column. Alumina would help retain the more polar ketone longer and would elute the alkene first. A mixture of hexanes was added in order to tighten the alumina column after which the excess hexanes were removed. Next, the sample was added followed by some and hexanes. Hexanes were constantly added and TLC was carried out to check if the resulting solution (which was removed from the column) contained any product. Once the TLC showed no traces of the product the solvent was switched to elude the ketone. Hexanes dissolve the reagent fluorene which is less polar and it is removed from the sample. After all the fluorene was removed, MTBE (methyl-tert-butyl-ether) was used as the solvent to remove the Fluorenone from the sample. The same procedure was carried out as in case of the hexanes until TLC showed no traces of the product. Once the product was obtained in a mixture of the solvent and product, the solution was boiled In order to obtain only the product (ether has a lower boiling point than ketone). Melting point of the product was taken in order to check the purity of the product. When the hexanes were used to remove the starting material from the sample, no spots appeared at all in the TLC plate for about 35 trials of the solution. The TLC plate remained blank showing proof of no compound other than the hexane itself. This error was expected since in the first part of the experiment, oxidation of fluoreneto Fluorenone was supposed to be done to a 50-50 level. As mentioned earlier, the oxidation had carried out longer than expected and hence the sample contained little or none of the fluorene. Thus, no value of Rf were obtained for the fluorenein the experiment. When the solvent was switched to MTBE, the Fluorenone was removed almost instantly. The Rf, for the last the slide that contained Fluorenone was 0. 11 and 0. 21 which falls within the range as earlier, indicating that the product obtained was indeed the ketone expected. To ensure the claim, melting point of the sample was taken. The melting point for the sample was 85 °C which is very close to the theoretical melting point of Fluorenone which is about 83  °C. Since the melting point was off by about 1.  °C it is assumed that some sources of error was obtained in the experiment. Since there was very little of the alkene in the sample, and none of it eluded out, it may have been stuck in the stationary phase. Hence when the ketone passed through the stationary phase it may have gotten contaminated leading to the error. Also all of the MTBE may not have evaporated out leading to some scope of error in the melting point of the product. There may have been some human error in determining the exact temperature at which the product began melting. The first part of the experiment showed significant error which affected the second part of the experiment as well. However, the goal of the experiment was to synthesize and separate fluorene from Fluorenone for which a good separation was obtained as can be concluded through the melting point. Even though the method did not go as planned, the purity of the final product was good. Questions: 1) (4 pts) a. What is the oxidizing agent in the conversion of fluoreneto fluorenone? What is the function of the Aliquat catalyst? c. Which compound, fluoreneor fluorenone has the highest R ¬f? Is it the most polar or nonpolar? d. Would changing to a more polar elution solvent increase or decrease Rf? a) The oxidizing agent in the conversion of fluorene to Fluorenone was oxygen in the air which was aided by a phase-transfer catalyst. b) The function of the Aliquat catalyst is to help the hydroxide ion move into the organic layer and where the hydroxide removes one of the fluorene protons. The Stark’s catalyst is a phase-transfer catalyst meaning it helps the migration of a reactant from one phase to another (here, OH- transfers from aqueous phase to organic). c) In this reaction Fluorenone has the lower Rf meaning it is more polar. Hence, Fluorene has higher Rf and lower polarity. This is due to the presence of C=O bond in the ketone (Fluorenone). d) Changing to a more polar elution would increase the Rf of the product. 2) (3 pts) Predict the order of elution of a mixture of triphenylmethanol, biphenyl, benzoic acid and methyl benzoate from an alumina chromatographic column. Ans: The compound that would elute first would be biphenyl, followed by methyl benzoate, triphenylmethanol, and finally benzoic acid. 3) (1 pts) What might possibly result if you used a column of alumina that was 5 cm instead of ten? Ans: If 5cm of the alumina is used instead of a 10cm alumina column the result obtained as the product would be purer than what was obtained experimentally. This is because as the eluent runs through the column some of it tends to naturally bind to the alumina surface. When more alumina is used the more eluent binds to the column and hence more product is lost. 4) (2pts) Consult the chart on the following page. In what range would you expect a new peak to appear if your oxidation is successful. Identify this peak on your IR; indicate the bond it represents. Also indicate the peaks for the C-H of an aromatic ring.

Essentials for Tree Seed Propagation

Essentials for Tree Seed Propagation Trees use seeds as a principal means of establishing their next generation in the natural world. Seeds serve as a delivery system for the transfer of genetic material from one generation to the next. This fascinating chain of events (the formation of seed to dispersal to germination) is very complex and still poorly understood. Some trees can easily be grown from seed but, for some trees, it may be much quicker and easier to propagate them from cuttings. Seed propagation can be a tricky process for a number of tree species. A small seedling can be very tiny and delicate when first germinated and often require much more care than a cutting. Seeds collected off tree hybrids or grafted stock can be sterile or the tree may  be off-character from the parent. For example, seeds collected from a pink dogwood will most likely flower white. What Stops Seeds From Germinating There are a number of important reasons a seed refuses to germinate under artificial conditions. Two major causes for unsuccessful tree seed germination are hard seed coats and dormant seed embryos. Both conditions are species-specific and every tree species has to subject the seeds to unique conditions to assure germination. Treating the seed properly is necessary before germination occurs and a seedling can be assured. Seed scarification and stratification are the most common methods of seed treatment and they will increase the chances of seed or nut germination. Scarification and Stratification The hard protective coating on some tree seeds is natures way of protecting the seed. But hard coats on some hard seed species actually inhibit the germination of the seed, because water and air cannot penetrate the hard coating. Interestingly, many tree seeds require two dormant periods (two winters) before the protective coating breaks down enough to germinate. The seeds must lay on the ground completely dormant for one full growing season, and then germinate the following growing season. Scarification is an artificial way to prepare hard seed coats for germination. There are three methods or treatments that will usually make seed-coats permeable to water: soaking in a solution of sulfuric acid, soaking in hot water or immersing the seed for a short period in boiling water, or mechanical scarification. Many dormant tree seeds need to be after-ripened before they can germinate. This is the most common cause of seeds failing to germinate. If the seed embryo produced by a tree is dormant, it must be stored at the proper temperature and in the presence of abundant supplies of moisture and air. Stratification is the process of mixing the seed in a moist (not wet) medium like peat moss, sand or sawdust, then placed in a storage container and stored in an area where the temperature is controlled at a low enough level to ripen the seed. This storage is usually over a definite period of time at a specific temperature (around 40 degrees F). Methods of Tree Seed Treatment by Species Hickory: This tree nut is generally considered to exhibit embryo dormancy. The common treatment is to stratify the nuts in a moist medium at 33 to 50 degrees F for 30 to 150 days. If cold storage facilities are not available, stratification in a pit with a covering of about 0.5 m (1.5 feet) of compost, leaves, or soil to prevent freezing will suffice. Prior to any cold stratification, nuts should be soaked in water at room temperature for two to four days with one or two water changes each day.Black Walnut: A walnut is generally considered to exhibit embryo dormancy. The common treatment is to stratify the nuts in a moist medium at 33 to 50 degrees F for two or three months. Although the seed coat is extremely hard it usually cracks, becomes water permeable, and does not need scarification.Pecan: A pecan does not fall into dormancy like other hickories and can be planted at any time with the expectation that the embryo will germinate. Still, the  pecan nut  is often collected and cold-stored for planting the next spring. Oak: Acorns of the white oak group generally have little or no dormancy and will germinate almost immediately after falling. These species should usually be planted in the fall. Acorns of the black oak group that exhibit variable dormancy and stratification are usually recommended before spring sowing. For best results, moist acorns should be held for four to 12 weeks at temperatures of 40 to 50 degrees F and can be placed in plastic bags without a medium, if turned frequently.Persimmon: Natural germination of common persimmon usually occurs in April or May, but two- to three-year delays have been observed. The main cause of the delay is a seed covering that causes a major decrease in water absorption. Seed dormancy also needs to be broken by stratification in sand or peat for 60 to 90 days at 37 to 50 degrees F. Persimmon is hard to artificially germinate.Sycamore:  American sycamore  needs no dormancy, and pre-germination treatments are usually not required for prompt germinati on.Pine: Seeds of most pines in temperate climates are shed in the autumn and germinate promptly the next spring. Seeds of most pines germinate without treatment, but germination rates and amounts are greatly increased by pretreating the seeds. This means storing seeds using moist, cold stratification. Elm: Under natural conditions, elm seeds that ripen in the spring usually germinate in the same growing season. Seeds that ripen in the fall germinate in the following spring. Although seeds of most elm species require no planting treatment, American elm will remain dormant until the second season.Beech: Seeds from beech trees need to overcome dormancy and require cold stratification for prompt germination. The seeds may take a combination of stratification and storage. Seed moisture level is the key to successful stratification in beech seeds. Beech is difficult to artificially germinate in significant amounts.