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For example, the specific rotation of (S)-2-ethyl-2-methyl succinic acid is found to be dependent on concentration; in what is known as the Horeau effect [3] the relationship between mole based ee and optical rotation based ee can be non-linear i.d. in the succinic acid example the optical activity at 50% ee is lower than expected.
This is a list of unsolved problems in chemistry. Problems in chemistry are considered unsolved when an expert in the field considers it unsolved or when several experts in the field disagree about a solution to a problem.
E2 competes with the S N 2 reaction mechanism if the base can also act as a nucleophile (true for many common bases). Scheme 1: E2 reaction mechanism. An example of this type of reaction in scheme 1 is the reaction of isobutylbromide with potassium ethoxide in ethanol. The reaction products are isobutene, ethanol and potassium bromide.
The numbers 200-900 would be confused easily with 22 to 29 if they were used in chemistry. khīlioi = 1000, diskhīlioi = 2000, triskhīlioi = 3000, etc. 13 to 19 are formed by starting with the Greek word for the number of ones, followed by και (the Greek word for 'and'), followed by δέκα (the Greek word for 'ten').
The "hydrogen ion" and the "electron" in these examples are respectively called the "reaction units." By this definition, the number of equivalents of a given ion in a solution is equal to the number of moles of that ion multiplied by its valence. For example, consider a solution of 1 mole of NaCl and 1 mole of CaCl 2.
Hammond's postulate (or alternatively the Hammond–Leffler postulate), is a hypothesis in physical organic chemistry which describes the geometric structure of the transition state in an organic chemical reaction. [1] First proposed by George Hammond in 1955, the postulate states that: [2]
In organic chemistry, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal catalyst .
A classic example for favoring the keto form can be seen in the equilibrium between vinyl alcohol and acetaldehyde (K = [enol]/[keto] ≈ 3 × 10 −7). In 1,3-diketones, such as acetylacetone (2,4-pentanedione), the enol form is more favored. The acid-catalyzed conversion of an enol to the keto form proceeds by proton transfer from O to carbon.