The chloride ion is more polar since it is above bromine on the periodic table and is more prone to hydrogen bonding due to its smaller size. Chloride ions are worse than bromine ions for nucleophilic attack, because the chloride ions are fully solvated and are not as available to attack. This is why Bromine ion is better nucleophile because is less electronegative and is willing to give up electrons. 3. What is the principal organic by-product of these two reactions?
This reaction was able to happen during designated lab time due to the fact that a phenol was used. Phenols or more reactive than unsubstitued benzene rings due to the presence of the alcohol on the benzene ring. The alcohol is considered an activating group due to the oxygen’s ability to donate its lone pairs into the benzene ring thus giving it more electrons and thus making it more nucleophilic and more likely to react with the introduced electrophilic species. As aforementioned, there are various products formed in this reaction the two major products formed though are the ortho and para products. It is debatable which product is more prominent due to steric reasons and the capability of each product to conduct in hydrogen bonding.
In this experiment, 293 mg of aldehyde was weighted for method 1 instead of 250 mg and. Although .7906 mg of phosphonium salt was added, this probably was not enough to complete the reaction. The only significant change throughout method was 1 was that the yellowish mixture became slightly lighter. However, it was found that after vacuum filtration, there was some white and yellow
Substrate concentration basically means the amount used for the substrate. The substrate in our experiment was 0.1% hydrogen peroxide. The 0.1% is the concentration amount. Just like temperature and pH, substrate concentration can speed the reaction only up to a certain limit. When we mixed pH 3 enzyme tube with substrate tube, we used 0.3 mL of hydrogen peroxide, but if we were to increase the amount, then the experiment would have been faster.
Thus, a higher percent yield was calculated for acetaminophen. Although, a second filtration was performed; however, a very low concentration of acetaminophen was recovered as a result of human errors, and the transfer of solution/solid contributed to product loss. However, the mass use to calculate percent yield was the first mass recorded because it may be more consistent than the mass measured after the second filtration. However, for further experiments, the percent yield must be calculated with the corresponding mass of product (actual yield) even though there is loss of product, the actual yield is the final concentration of the recovered product in the experiment. Thus, the results may be more conclusive if the actual percent yield was used.
This is because if taken simple distillation into consideration. The column has a lower temperature at the top then the bottom thus there is a lower vapor pressure (Gilbert 126). And therefore the bottom as a higher temperature and in order to reach an equilibrium the temperature gradient is formed as shown the graph above (Gilbert 126).The column is utilized so that the vapor reaches the condenser at the bottom of the column and therefore several simple distillation trials need to be done in order to ensure that the distillation can be very effective (Gilbert 126). Boiling point and vaporization are inversely proportional, so lower boiling point means faster vaporization so in this case acetone moves down the column faster leaving the 1-propanol for the last fraction (Gilbert 126). That being said, in the fractional distillation, the rings act as the trials in the simple distillation (Gilbert 126).
Study indicates that ethanol at an optimal concentration of 25% (v/v) is more effective than water for the extraction of polyphenols which reached the maximum of 69.75 mg of GAE/ g of dry black gram powder The use of lower concentrations of alcohol has the added advantage that the proteins are not likely to be denatured and possibly their physico-chemical and functional properties are not impaired and indicated that the protein content of the extract is not decreased by the extraction at low concentrations of alcohol. There will be drop in total phenolic content with 100% ethanol9. Effect of extraction temperature on extraction of phenolic compounds The extraction of phenolic compounds was checked in the temperatures ranging from 300C to 600C. At 30°C, there was increase in polyphenol extraction. At higher temperature, the extraction of polyphenols was not effective; this may be due the decomposition of phenolic compounds or may be due to the breakdown of phenolic content which are present in the sample network.
The average result obtained was 22.5% and is close to it’s literal value. This experiment had also proven to have shown effective transfer of solids and liquids as values of 1st and 2nd results, namely 22% and 23% respectively, were similar thereby showing consistency in results. Phenolphthalein indicator was proven to be more suitable as an indicator as compared to Methyl Orange in this experiment. This is because Phenolphthalein the pH values of HCl involved in this experiment were in range of the pH values that bring about colour change in the Phenolphthalein indicators. (Approximate pH ranges for color change: 8.0-9.8) Low pH values are preferred for Methyl Orange.
We are also able to better control and determine the volume of NaOH in the burette needed to neutralise HCI, CH3COOH and the unknown acid. This is because the amount of NaOH droplet can be altered when a burette is used thus, the NaOH solution can be dripped per drop at the time nearing the end point of the experiment as the colour changes rather quickly from light pink to pink. Conclusion: In conclusion, titration is an effective technique to determine the equivalence point, pH range, pKa, Ka and molecular mass of the unknown acid of the acid-base reaction. This technique is dependent on the colour change of the indicator which makes it easier to determine the end point of the experiment. Postlab Exercises: 1.
The Rf value of the pure isolated caffeine was 0.28. This was 0.16 higher than the Rf value of the pure caffeine. Although the value of the isolated caffeine is nearly double that of the pure caffeine, it appears that caffeine was separated from Excedrin, but the sample was not pure. It still had other analgesics present. This is concluded from the location
After recrystallization and purification, the percent yield was 63.620% (0.724 grams) and the melting point was 262-263°C (see Table 1). The literature melting is 262-264°C. The low percent yield could be due to lack of recrystallization of the crude product. In addition, some of the crystals may not have been transferred to the funnel from the flask. The IR analysis indicated a distinctive peak at 1778.43 representing ketone, and another peak at 1226.73 representing ether.
According to the IR spectra received for the sample of Isopentyl Acetate, there were three main signals present. The first of the three signals was present at a wavenumber of 2,961.70 cm^-1. A signal at this wavenumber indicates that there are hydrogen-carbon bonds present in this sample of Isopentyl Acetate. According to the structural formula of Isopentyl Acetate, carbon-hydrogen bonds are indeed present in its structure. The second of the three signals was present at a wavenumber of 1,742.88 cm^-1 .
As seen in the trend of both buffer, once the pH is lower than 3, the slope of dv/dpH increase drastically, showing the decreasing effects of the buffer. On the other hand, in the trend of both buffer on the right side of graph shows when NaOH is added, the change in pH is more drastic once past about pH 5. Although buffer 1 and buffer 2 shows a similar trend, the plot of buffer 1 is above the plot of buffer 2. The reason for this is that buffer 1 is made by an acid and base with an almost equal concentration. This makes buffer 1 a greater buffer compared to buffer 2.