Numerous previous investigations of the bromination of toluene have dealt with the effects of light, temperature, concentrations, catalysts, and solvents. Of various interpretative hypotheses hitherto advanced, none accounts adequately for all the phenomena reported.The observation in this laboratory that side-chain bromination of toluene is markedly facilitated by traces of organic peroxides and oxygen may be interpreted in a manner that permits the correlation of many hitherto unrelated, and some apparently discordant, data. In the light of the present and previous studies1 the authors believe that hydrogen bromide is a source of bromine atoms in the presence of oxygen and sufficiently active oxygen-carriers. The working hypothesis proposed is that sidechain bromination of toluene is a chain reaction initiated by bromine atoms, whereas nuclear bromination is a slow bimolecular reaction in which bromine atoms do not participate. It is the purpose of the present communication to show that this hypothesis is consistent with the earlier experimental data, and to report certain supplementary studies that also tend to support it.REVIEW OF THE LITERATURE It was early observed that nuclear and side-chain bromination of toluene are two separate and independent reactions and that their relative rates, and consequently the ratios of their respective products, vary widely with the experimental conditions.2 Ordinarily o-and p-bromotoluenes (hereafter referred to as "bromotoluenes") are the only products of nuclear bromination. m-Bromotoluene is formed only in very high bromine concentrations, and in the presence of a catalyst.3 Even then, the yield is only a fraction of one per cent. Likewise, polybromo compounds are not formed except in the presence of large amounts of catalyst, such as thirty mole per cent, of aluminum bromide,2 or beryllium bromide.4
Purpose This paper explores a computational method to resolve some of the problems of external normalization in the life cycle impact assessment (LCIA) process of midpoint characterized impacts. Problems inherent to external normalization (per capita per year for a defined region) that reduce the ability to accurately calculate the most significant impact categories include a) Bias created by a range of measurement disparities b) Inverse proportion of the scale of the reference system impacts to the normalized product system impacts c) Measurement and methodological uncertainties Methods This paper demonstrates a method called Process Inventory Dataset (PID) normalization. PID normalization modifies the normalized impact value by a normalizing factor which puts a probability distribution on average normalized impact categories for an entire process inventory dataset. Results PID normalization allows for significant variation of normalized impact ratio impact values among impact categories and among materials and processes. PID normalization works with incomplete process inventory and normalization data to deliver normalized impact ratio values that more accurately identify the impact categories with the most significant impacts in the LCIA process. Conclusions Although PID normalization does not eliminate all of the bias that can occur from midpoint characterization and external normalization and may not reduce all uncertainties, it substantially trims the effects of normalization bias and eliminates inverse proportionality within one normalization dataset. It allows for a more accurate interpretation of normalized and weighted life cycle assessment results.
To address climate change and other are sustainability imperatives, the private sector has launched various initiatives that are aimed to evaluate and reduce the impact throughout the life cycle of consumer products. Recently, multi-national retailers and manufacturers have initiated a unified approach in creating sustainable indexing programs for the products they make and sell. Often overlooked in addressing pressing sustainability imperatives such as climate change are the consumptive patterns and impact of consumer goods during the consumer use phase. This article presents an empirical study of the consumer use phase of laundry care with a specific focus on electricity consumption and carbon dioxide emissions. By understanding the climate change impact associated with the consumer use phase, innovations in the manufacturing phase as well as life cycle benefits of different technologies and consumer actions can be explored. Incentives offered to consumers on appropriate technologies used in this phase can be examined to identify the effectiveness of change-agents. Our results indicate that a carbon dioxide reduction of 105 MMT and electricity savings of 142 thousand GWh can be obtained by optimizing and modifying technological and consumer behavior strategies. This is roughly equivalent to removing 12.1% of the 135.4 M passenger cars in the United States per year or taking 23 coal power plants off the grid. In addition, more than 60% of water consumption (512 billion gallons) while laundering can be reduced through these strategies.
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