Synthesis of bromochloromethane using phase transfer catalysis
- Authors: Brooks, Lancelot L
- Date: 2011
- Subjects: Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10382 , http://hdl.handle.net/10948/d1008162 , Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Description: The synthesis of bromochloromethane (BCM) in a batch reactor, using phase transfer catalysis, was investigated. During the synthetic procedure, sodium bromide (100.0g, 0.97mol) along with an excess amount of dichloromethane (265.0g, 3.12 mol) was charged to a reactor containing benzyl triethylammonium chloride (13 mmol), dissolved in 50 ml of water. The bench scale reactions were all carried out in a Parr 4520 bench top pressure reactor coupled to a Parr 4841 temperature controller. The method produced a 50.0 percent yield of the product BCM after a reaction time of 12 to 13 hours. The main objective for this investigation was to optimize the abovementioned reaction with respect to yield and reactor throughput. Quantitative analysis of BCM was performed on a Focus Gas Chromatograph, fitted with a flame ionization detector, and a BP20 column (30m × 0,32mm ID × 0,25 mm). Delta software, version 5.0, was applied for data collection and processing. The injector and detector port were set at 250°C and 280°C, respectively. The oven temperature was set and held at 40°C for a period of 2 minutes, then gradually increased at a rate of 10°C/min to 130°C, with the final hold time set for 1 minute. An analytical method for the quantitative analysis of BCM was developed, optimized and validated. Validation of the analytical method commenced over a period of three days, and focussed the following validation parameters: Accuracy, precision, and ruggedness. Statistical evaluation of the results obtained for precision showed that the error between individual injections is less than 2 percent for each component. However, ANOVA analysis showed a significant difference between the mean response factors obtained in the three day period (p-value < 0.05). Thus we could conclude that the response factors had to be determined on each day before quantitatively analyzing samples. The accuracy of the analytical method was assessed by using the percent recovery method. Results obtained showed that a mean percent recovery of 100.18 percent was obtained for BCM, with the absolute bias = 0.0004, and the percent bias = 0.18 percent. Hence the 95 confidence intervals for the percent recovery and percent bias are given by: (Lz, Uz) = (100.56 percent percent 102.15 percent), 13 (LPB, UPB) = (0.56 percent, 2.15 percent), respectively. Since the 95 percent confidence interval for the percent recovery contains 100, or equivalently, the 95 percent confidence interval for percent bias contains 0, the assay method is considered accurate and validated for BCM. In the same manner the accuracy and percent recovery for DCM and DBM was evaluated. The method was found to be accurate and validated for DBM, however, slightly biased in determining the recovered amount of DCM. With the analytical method validated, the batch production process could be evaluated. A total of six process variables, namely reaction time, water amount, temperature, volume of the two phases, stirring rate, and catalyst concentration, were selected for the study. The effects of the individual variables were determined in the classical manner, by varying only the one of interest while keeping all others constant. The experimental data generated was fit to a quadratic response surface model. The profile plots that were obtained from this model allowed a visual representation of the effect of the six variables. The experimental results obtained showed that the reaction follows pseudo zero-order kinetics and that the rate of the reaction is directly proportional to the concentration of the catalyst. The reaction obeys the Arrhenius equation, and the relatively high activation energy of 87kJ.mol -1 signifies that the rate constant is strongly dependent on the temperature of the reaction. The results also showed that the formation of BCM is favoured by an increase in the reaction temperature, catalyst concentration, and a high organic: aqueous phase ratio. Thus the synthesis of BCM using phase transfer catalyst could be optimised, to obtain a 100 percent yield BCM, by increasing both the reaction temperature to 105°C, and the concentration of the phase transfer catalyst -benzyl triethylammonium chloride - to 5.36 mol percent. The reaction time was also reduced to 6 hours.
- Full Text:
- Date Issued: 2011
- Authors: Brooks, Lancelot L
- Date: 2011
- Subjects: Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10382 , http://hdl.handle.net/10948/d1008162 , Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Description: The synthesis of bromochloromethane (BCM) in a batch reactor, using phase transfer catalysis, was investigated. During the synthetic procedure, sodium bromide (100.0g, 0.97mol) along with an excess amount of dichloromethane (265.0g, 3.12 mol) was charged to a reactor containing benzyl triethylammonium chloride (13 mmol), dissolved in 50 ml of water. The bench scale reactions were all carried out in a Parr 4520 bench top pressure reactor coupled to a Parr 4841 temperature controller. The method produced a 50.0 percent yield of the product BCM after a reaction time of 12 to 13 hours. The main objective for this investigation was to optimize the abovementioned reaction with respect to yield and reactor throughput. Quantitative analysis of BCM was performed on a Focus Gas Chromatograph, fitted with a flame ionization detector, and a BP20 column (30m × 0,32mm ID × 0,25 mm). Delta software, version 5.0, was applied for data collection and processing. The injector and detector port were set at 250°C and 280°C, respectively. The oven temperature was set and held at 40°C for a period of 2 minutes, then gradually increased at a rate of 10°C/min to 130°C, with the final hold time set for 1 minute. An analytical method for the quantitative analysis of BCM was developed, optimized and validated. Validation of the analytical method commenced over a period of three days, and focussed the following validation parameters: Accuracy, precision, and ruggedness. Statistical evaluation of the results obtained for precision showed that the error between individual injections is less than 2 percent for each component. However, ANOVA analysis showed a significant difference between the mean response factors obtained in the three day period (p-value < 0.05). Thus we could conclude that the response factors had to be determined on each day before quantitatively analyzing samples. The accuracy of the analytical method was assessed by using the percent recovery method. Results obtained showed that a mean percent recovery of 100.18 percent was obtained for BCM, with the absolute bias = 0.0004, and the percent bias = 0.18 percent. Hence the 95 confidence intervals for the percent recovery and percent bias are given by: (Lz, Uz) = (100.56 percent percent 102.15 percent), 13 (LPB, UPB) = (0.56 percent, 2.15 percent), respectively. Since the 95 percent confidence interval for the percent recovery contains 100, or equivalently, the 95 percent confidence interval for percent bias contains 0, the assay method is considered accurate and validated for BCM. In the same manner the accuracy and percent recovery for DCM and DBM was evaluated. The method was found to be accurate and validated for DBM, however, slightly biased in determining the recovered amount of DCM. With the analytical method validated, the batch production process could be evaluated. A total of six process variables, namely reaction time, water amount, temperature, volume of the two phases, stirring rate, and catalyst concentration, were selected for the study. The effects of the individual variables were determined in the classical manner, by varying only the one of interest while keeping all others constant. The experimental data generated was fit to a quadratic response surface model. The profile plots that were obtained from this model allowed a visual representation of the effect of the six variables. The experimental results obtained showed that the reaction follows pseudo zero-order kinetics and that the rate of the reaction is directly proportional to the concentration of the catalyst. The reaction obeys the Arrhenius equation, and the relatively high activation energy of 87kJ.mol -1 signifies that the rate constant is strongly dependent on the temperature of the reaction. The results also showed that the formation of BCM is favoured by an increase in the reaction temperature, catalyst concentration, and a high organic: aqueous phase ratio. Thus the synthesis of BCM using phase transfer catalyst could be optimised, to obtain a 100 percent yield BCM, by increasing both the reaction temperature to 105°C, and the concentration of the phase transfer catalyst -benzyl triethylammonium chloride - to 5.36 mol percent. The reaction time was also reduced to 6 hours.
- Full Text:
- Date Issued: 2011
The impact of the new dividend withholding tax on regulated investment intermediaries
- Authors: Schafer, Carolyn
- Date: 2011
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:880 , http://hdl.handle.net/10962/d1001634
- Description: The introduction of the proposed new Dividends Tax will have a significant impact on financial institutions such as Collective Investment Schemes, Linked Investment Service Providers and Long-term Insurers. The reason for this is that South African listed companies declaring local dividends will not necessarily have all the details of and know the identity of their shareholders. These financial institutions may be regarded as regulated intermediaries in terms of the new Dividends Tax legislation and therefore may have the responsibility of withholding the Dividends Tax from dividends received on behalf of their clients, who may in most cases be the beneficial owners of the underlying equity shares. The motivating factor for the research is the fact that there does not appear to be any guidance on the impact of the new Dividends Tax on financial institutions, since the Dividends Tax is new legislation. The research problem addressed in this thesis is how the systems and processes of a financial institution will be affected by the implementation of the new Dividends Tax. The research took the form of a case study designed to investigate the impact of the Dividends Tax on the financial institution at which the researcher is employed. The data required for the research was collected by means of a study of the relevant legislation enacted in connection with the topic, journal articles in financial/tax journals, as well as articles published in the media. The systems and processes presently in place, as well as the changes to these systems that will be needed to accommodate the new dividend tax were ascertained by means of in-depth interviews with relevant staff at the financial institution. In addition, the researcher also applied her personal knowledge of the business of the financial institution at which she works to the problem. As a result of the research it was determined that a Collective Investment Scheme, Linked Investment Service Provider and Long-Term Insurer will all be regarded as regulated intermediaries for the purposes of the new dividend withholding tax. This means that these financial institutions will be required to withhold Dividends Tax from dividends paid to their clients and pay this Dividends Tax so withheld to SARS. Furthermore, the findings of the research confirmed that the new Dividends Tax will have a significant impact on the client services department in areas such as notifying clients, training of client service staff, handling of declaration of exemption forms received from clients, amending client statements and tax certificates (to cater for the new Dividends Tax). In addition to this, it was ascertained that significant systems development will be required by these financial institutions in order to comply with the new Dividends Tax legislation. This would include the development of data input fields to enable users to capture the relevant information required and development of the system to enable it to flag local dividends received to which the Dividends Tax applies. The system would also need to cater for Secondary Tax on Companies credits as well as foreign tax rebates. The system should also be able to calculate the amount of Dividends Tax to withhold per dividend received by a client, as well as be able to handle the payment of the Dividends Tax to SARS and the refund to clients of Dividends Tax over deducted. It is essential that systems are able to flag the correct date of payment of the dividend so that the Dividends Tax can be paid over timeously to SARS in order to avoid interest and penalties being levied. To summarise, the new Dividends Tax has a significant impact on these financial institutions in areas such as client services, administration and system development.
- Full Text:
- Date Issued: 2011
- Authors: Schafer, Carolyn
- Date: 2011
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:880 , http://hdl.handle.net/10962/d1001634
- Description: The introduction of the proposed new Dividends Tax will have a significant impact on financial institutions such as Collective Investment Schemes, Linked Investment Service Providers and Long-term Insurers. The reason for this is that South African listed companies declaring local dividends will not necessarily have all the details of and know the identity of their shareholders. These financial institutions may be regarded as regulated intermediaries in terms of the new Dividends Tax legislation and therefore may have the responsibility of withholding the Dividends Tax from dividends received on behalf of their clients, who may in most cases be the beneficial owners of the underlying equity shares. The motivating factor for the research is the fact that there does not appear to be any guidance on the impact of the new Dividends Tax on financial institutions, since the Dividends Tax is new legislation. The research problem addressed in this thesis is how the systems and processes of a financial institution will be affected by the implementation of the new Dividends Tax. The research took the form of a case study designed to investigate the impact of the Dividends Tax on the financial institution at which the researcher is employed. The data required for the research was collected by means of a study of the relevant legislation enacted in connection with the topic, journal articles in financial/tax journals, as well as articles published in the media. The systems and processes presently in place, as well as the changes to these systems that will be needed to accommodate the new dividend tax were ascertained by means of in-depth interviews with relevant staff at the financial institution. In addition, the researcher also applied her personal knowledge of the business of the financial institution at which she works to the problem. As a result of the research it was determined that a Collective Investment Scheme, Linked Investment Service Provider and Long-Term Insurer will all be regarded as regulated intermediaries for the purposes of the new dividend withholding tax. This means that these financial institutions will be required to withhold Dividends Tax from dividends paid to their clients and pay this Dividends Tax so withheld to SARS. Furthermore, the findings of the research confirmed that the new Dividends Tax will have a significant impact on the client services department in areas such as notifying clients, training of client service staff, handling of declaration of exemption forms received from clients, amending client statements and tax certificates (to cater for the new Dividends Tax). In addition to this, it was ascertained that significant systems development will be required by these financial institutions in order to comply with the new Dividends Tax legislation. This would include the development of data input fields to enable users to capture the relevant information required and development of the system to enable it to flag local dividends received to which the Dividends Tax applies. The system would also need to cater for Secondary Tax on Companies credits as well as foreign tax rebates. The system should also be able to calculate the amount of Dividends Tax to withhold per dividend received by a client, as well as be able to handle the payment of the Dividends Tax to SARS and the refund to clients of Dividends Tax over deducted. It is essential that systems are able to flag the correct date of payment of the dividend so that the Dividends Tax can be paid over timeously to SARS in order to avoid interest and penalties being levied. To summarise, the new Dividends Tax has a significant impact on these financial institutions in areas such as client services, administration and system development.
- Full Text:
- Date Issued: 2011
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