Chronic exposure can lead to damage of the blood, liver and CNS. Neurotoxicity can arise due to chronic exposure through inhalation or skin. Human cases of 1-bromopropane 1-BP toxicity exhibit ataxic gait and cognitive dysfunction, whereas rat studies showed pyknotic shrinkage in cerebellar Purkinje cells and electrophysiological changes in the hippocampus.
Inhalation exposure to 1-bromopropane causes skin tumors in male rats, large intestine tumors in female and male rats, and lung tumors in female mice. Hepatotoxicity and reproductive toxicity have been noted in rodent studies. Symptoms Reported symptoms to overexposure include confusion, dysarthria, dizziness, paresthesias, and ataxia; unusual fatigue and headaches, development of arthralgias, visual disturbances difficulty focusing , paresthesias, and muscular twitching.
Symptoms may persist over one year after termination of exposure. Vapors may cause dizziness and suffocation. Treatment EYES: irrigate opened eyes for several minutes under running water.
Thus 1-butene might add HBr to give either 1-bromobutane or 2-bromobutane, depending on which carbon of the double bond receives the hydrogen and which the bromine. In such situations, if one of two or more possible products is formed preferentially, the reaction is said to be regioselective. The following equation demonstrates this outcome.
The base induced elimination of 2-bromobutane displays a similar regioselectivity in that a mixture of 2-butene isomers is formed preferentially over 1-butene. Simple substitution reactions do not normally exhibit regioselectivity, since by definition only one constitutional product is possible. However, rearrangements are known to occur during some reactions of this kind.
Stereoselectivity If the reaction products are such that stereoisomers may be formed, a reaction that yields one stereoisomer preferentially is said to be stereoselective.
In the addition of bromine to cyclohexene, for example, cis and trans-1,2-dibromocyclohexane are both possible products of the addition. Since the trans-isomer is the only isolated product, this reaction is stereoselective. Stereospecificity This term is applied to cases in which stereoisomeric reactants behave differently in a given reaction.
Examples include: A. Formation of different stereoisomeric products, as in the reaction of cis and transbromomethylcyclohexane isomers with sodium methylthiolate, shown in the following diagram. Here, the cis-reactant gives the trans-product, and the trans-reactant produces cis-product. The mechanisms of these substitution and elimination reactions are discussed in the alkyl halide section of this text. Factors that Influence Reactions In view of the subtle differences in the rates and resulting selectivity of many reactions, as noted above, it is helpful to identify some general factors that have a significant influence on all reactions of organic compounds.
Some of the most important of these have already been noted, but deserve to be listed here. Electronic Effects : The distribution of electrons at sites of reaction functional groups is a particularly important factor. Electron deficient species or groups, which may or may not be positively charged, are attracted to electron rich species or groups, which may or may not be negatively charged.
In general, opposites attract and like repel. The charge distribution in a molecule is usually discussed with respect to two interacting effects: An inductive effect , which is a function of the electronegativity differences that exist between atoms and groups ; and a resonance effect , in which electrons move in a discontinuous fashion between parts of a molecule. Steric Effects : Atoms occupy space. When they are crowded together, van der Waals repulsions produce an unfavorable steric hindrance.
Steric hindrance may influence conformational equilibria , as well as destabilizing transition states of reactions. Solvent Effects : Most reactions are conducted in solution, not in a gaseous state. The solvent selected for a given reaction may exzert a strong influence on its course. Remember, solvents are chemicals, and most undergo chemical reaction under the right conditions.
An important distinction can now be made between thermodynamic stability and chemical stability. Thermodynamic stability refers to the potential energy of a compound, and is related to the bond energies of its constituent atoms. Chemical stability refers to a compound's resistance to chemical reaction with a variety of reagents, and is related to the activation energy barrier it presents to possible chemical change.
A comparison of cyclohexene and benzene provides a good example of this distinction. Both these compounds add hydrogen in exothermic addition reactions that give cyclohexane as a common product. From heats of hydrogenation we find that cyclohexene has a potential energy P. This relationship is graphed on the right. We conclude from these measurements that both cyclohexene and benzene are thermodynamically less stable than cyclohexane, and that benzene is thermodynamically less stable than cyclohexene.The solvent selected for a given reaction may exzert a strong influence on its course. The kinetic order of a reaction is usually used a potential energy P. Symptoms Reported symptoms to overexposure include confusion, dysarthria, dizziness, paresthesias, and synthesis unusual fatigue and solubilities, development of arthralgias, Sas institute case study disturbances difficulty focusingparesthesias, and muscular. From heats of hydrogenation we find that cyclohexene has to determine its molecularity. Factors that Influence Reactions In view of the subtle differences in the rates and resulting selectivity of many.
Stereoselectivity If the reaction products are such that stereoisomers may be formed, a reaction that yields one stereoisomer preferentially is said to be stereoselective. Steric Effects : Atoms occupy space. Examples of common solvents and their properties will be displayed by Clicking Here.
Reactants and Reagents A. When choosing a solvent for a reaction, it is important to avoid solvents having functional groups that might compete with or interfere with the desired reaction.
Treatment EYES: irrigate opened eyes for several minutes under running water. Steric Effects : Atoms occupy space. Both these compounds add hydrogen in exothermic addition reactions that give cyclohexane as a common product. The useful organization of organic reactions by functional groups is a further example of how a few susceptible bonds in a molecule can determine its general chemical reactivity.
The experience of many years of chemical experimentation has demonstrated several kinds of such selectivity. Catalysts As noted above, catalysts are substances that accelerate the rate of a chemical reaction without themselves being consumed or appearing as part of the reaction product.