Complexation of porphyrin with the metal will cause the shifts of Q bands in the UV-Vis spectra in the range of 500-700 nm as shown in Figure 2.7. This can be observed by the disappearance of two Q bands out of four as the porphyrin undergoes the change from D4h symmetry to D2h symmetry (Rita Giovannetti, 2012). The Q-bands were denoted as α and β. The coordination of porphyrin to Ni(II), Sn(IV) or Pd(II) which can form stable square planar complexes generally consists of a higher α peak (Figure 2.7 (A)), while the coordination of porphyrin to Cd(II) which forms a complex that can easily be displaced by protons will show a higher β peak (Figure 2.7(B)).
The common solvents and counter-ions employed in the synthesis metalloporphyrin are chloroform, methanol, dimethylforamide, acetate buffer, pyridine, metal carbonyl and acetylacetone. In general, the selection of solvent depends on the solubility of porphyrin. For example, the chloroform was selected for metallation of meso-tetraphenylporphyrin (TPP) due to the solubility of TPP in chloroform. Besides, the metal counter-ion as “carrier” of metal should be considered as well, as the solubility of metal salt also affect the metallation of porphyrin.
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In nature, porphyrins such as hermatoporphyrin IX, coproporphyrin and uroporphyrins are water soluble. Since the isolation of these porphyrins, the chemistry water-soluble porphyrins were intensively studied to develop biological useful device. The notion “water-soluble porphyrin” suggests at least water soluble in pH 1-14 only consider as water-soluble porphyrin. General, water-soluble porphyrin can be divided into three classes: positively charged porphyrin, negatively charged porphyrin and neutral porphyrin (Simonnaeux et al., 2011) as shown in Table
From the vial labeled “AE,” aspirin (0.533 g) was placed into a 50 mL Erlenmeyer flask with a boiling stick. Toluene (20 mL) was brought to a boil on a hot plate. The boiling toluene (10 mL) was then added to the aspirin until the solid dissolved completely. After allowing the solution to reach room temperature, the solution was placed in an ice bath for 16 minutes. After the crystals
After placing in darkness the colorless solution resulted by reformation of the radical intermediates to a new thermodynamic product via C-N bond at room temperature. UV-Vis was conducted on the solution before and after the irradiation with sunlight: UVtoluene 554.92nm, A=0.12 before irradiation and A=1.05 after. The peak at 554.92nm corresponds to yellow/green light and its complementary colour is red/violet. This validates the solutions violet color. The increased absorbance was accounted for an increase in the radical component. The radical was formed when exposed to light, which was visually apparent with the purple coloration and proved the thermodynamic dimer was also photochromic. When dimer 4 is exposed to light photons collide with the molecule and impart energy upon them. This energy is significant enough to break the bond between the two rings and results
CHE 135 Experiment 2, General Chemistry III Lab, Spring Quarter 2015-2016, DePaul University. [Online] htps://www.d2l.depaul.edu (April 19, 2016).
This experiment involved three steps: synthesis of aspirin, isolation and purification, and the estimation of purity of the final product. The synthesis involved the reaction of salicylic acid and acetic anhydride in the presence of a catalyst, phosphoric acid, H3PO4. When the aspirin was prepared, it was isolated and filtered. The percentage yield of the synthesis was calculated to be 78.42%. The experimental melting point range of aspirin was determined to be 122 -132°C. Due to its wide range, and lower value than that of the theoretical melting point of 136°C, it was
Both Aspirin and the Unknown are soluble in dichloromethane, due to their non-polar characteristics. To separate the two components, sodium bicarbonate was added (see figure 3). Sodium bicarbonate reacted with aspirin and converted it to a salt, also forming water and carbon dioxide. It was observed that the solution "fizzed" when this reaction took place, showing the release of carbon dioxide. The newly formed salt then traveled to an aqueous layer where it was soluble, while the unknown remained in the dichloromethane layer. The two layers were then separated. To collect an aspirin solid, the combination of the addition of HCl and the process of vacuum filtration helped to break down the salt and form a solid. Then the solid was placed in the Fisher Scientific Biotemp Oven to dry it to a constant mass of 0.091 g, 32.97% of the total composition. The
The purpose of this lab was to synthesize aspirin, determine the theoretical yield, compare the percent yield to the theoretical yield and test the purity of aspirin by adding Iron (III) chloride to the product.
The isolation of aspirin, acetaminophen, and caffeine from Excedrin utilized the differing acidities and polarities of the three compounds. Extraction involved separating the three components by reacting them with HCL and NaOH, while thin layer chromatography involved separating the isolated compounds on a TLC plate. The binder was the first component extracted; followed by aspirin, acetaminophen, and caffeine was extracted last since it is a neutral and polar compound. The entire process can be seen in figure 1. The most utilized methods of extraction were gravity filtration and vacuum filtration which are displayed in figures 3 and 4 respectively. These methods were utilized to separate compounds based upon their differing
Manufacturing theophylline formulations come with challenges for both the anhydrous and hydrate. For the anhydrous form, a study showed that the wet granulation of theophylline anhydrous in conjunction with microcrystalline cellulose, led to the formation of the monohydrate form of the drug. This is significant because the monohydrate has slower dissolution than the anhydrous form of theophylline. Thus the method of manufacture is highly important as the study showed directly compressed pellets had better dissolution profiles. Also it shows the importance of the choice of excipients as pellets manufactured via wet granulation in the absence of microcrystalline cellulose showed similar release to that of directly anhydrous theophylline.
The purpose of this experiment was to perform a nucleophilic substitution reaction to construct a biologically active compound from two simple parts and then to recrystallize the product collected, which is a purification technique that purifies solids based on differences in solubility. In order to accomplish this, other techniques such as heating at reflux, and suction filtration were used. Heating at reflux is a technique used in lab that allows a solution to be heated for a certain amount of time once it begins boiling. Suction filtration is a separation technique that is combined with a water aspirator and was used to collect the product from this experiment, which was 2-methylphenooxyacetic acid.
Science A CH1HP H Unit Chemistry C1 Chemistry Unit Chemistry C1 Monday 10 June 2013 1.30 pm to 2.30 pm Mark 1 2 3 4 5 6 7 TOTAL For this paper you must have: a ruler the Chemistry Data Sheet (enclosed).
With a large amount of confusion surrounding the public, religions began to voice their opinions. Some religious views were supported by the media, whereas medical support was varied but limited as many felt that chloroform was unethical (Church History, 2006). The Church of England preached against the use of chloroform relating to the bible “God caused a deep sleep to fall upon Adam… he took one of his ribs and closed up the flesh”, Simpson challenged this as it shows the first surgical operation on humans (Robinson, 1996). Simpson discovered that during labour a women can experience anxiety and dread towards birth but with chloroform those feelings disappear (Poovey, 1986). A journalist for New Vision tested securities around chloroform
CHE 133 Experiment 3, General Chemistry II Lab, Spring Quarter 2014-2015, DePaul University. [Online] https://www.d2l.depaul.edu (accessed April 25, 2015)
Olmsted, John III; Williams, Greg; Burk, Robert C. Chemistry, 1st Canadian ed.; John Wiley and Sons Ltd: Mississauga, Canada, 2010, pp 399 - 406
Then the mixture with a few boiling chips were added in a reflux condenser for thirty minutes. After this period the hot chloroform solution was filtered through a Hirsch funnel, and three more washes of the bark were performed with additional hot chloroform, (3X10ml). In the last step for the purification of butelin the previous chloroform solution was passed over a microscale column of silica gel3 (9cm) and the clean product was collected in a 250ml RBF. Before the rearrangement reaction 10ml of the clean product was collected for evaporation using a rotary evaporator, for the determining of NMR spectrum. Moreover two drops of this product was used as a sample for TLC chromatography. The second step of this experiment includes the rearrangement of betulin to alloetulin. In this stage 120mg of p-toluenesulfonic acid were dissolved in the remaining chloroform solution of betulin. Then 3 drops of water and one small boiling chip were added in the solution and a reflux condenser was used for 60 minutes. After this period the chloroform solution was cooled for 15mins. Thereafter the solution was washed three times with 5% sodium bicarbonate and sodium sulfate was used to dry the chloroform solution. In the end, filtration of the drying agent and rotary evaporation of the chloroform solution, gave the alloebtulin. Finally two more drops of this product was used in the same sample of butelin
This report presents the synthesis of Aspirin (acetylsalicylic acid), as the product of the reaction of salicylic acid with ethanoic anhydride under acidic conditions. Aspirin was purified through recrystallisation by vacuum filtration, followed by desiccation of the Aspirin crystal over silica gel. The percentage yield was calculated as 44.89% and a sample of Aspirin was analysed using infra-red spectroscopy and compared to the spectrum of pure Aspirin, this served as an introduction to the identification of functional groups in organic compounds. The melting point was calculated using an IA9000M apparatus and recorded to be 35.2°C, which was slightly below the melting point of pure Aspirin; known to be between 138-140°C. Both IR spectroscopy and melting point measurement were used verify the purity of synthetic Aspirin made, which proved to be fairly pure under these laboratory conditions.