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K 2 O crystallises in the antifluorite structure. In this motif the positions of the anions and cations are reversed relative to their positions in CaF 2, with potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium. [6] [7] K 2 O is a basic oxide and reacts with water violently to produce the caustic potassium ...
Gutmann, a chemist renowned for his work on non-aqueous solvents, described an acceptor-number scale for solvent Lewis acidity [4] with two reference points relating to the 31 P NMR chemical shift of Et 3 PO in the weakly Lewis acidic solvent hexane (δ = 41.0 ppm, AN 0) and in the strongly Lewis acidic solvent SbCl 5 (δ = 86.1 ppm, AN 100).
The cationic metal centres act as Lewis acid sites while the anionic oxygen centres act as Lewis bases. Surface hydroxyl groups can serve as Brønsted acid or base sites as they can give up or accept a proton. [14] The surface of most metal oxides will be, to some extent, hydroxylated under normal conditions when water vapor is present. [15]
Extremely Lewis acidic metal centers can, however, cleave the carbon-boron bond in BARF. [12] NaBAr F 4 can be used in deprotection of acetal or ketal-protected carbonyl compounds. [13] [14] For example, deprotection of 2-phenyl-1,3-dioxolane to benzaldehyde can be achieved in water in five minutes at 30 °C. [15]
Heterogeneous OER is sensitive to the surface in which the reaction takes place and is also affected by the pH of the solution. The general mechanism for acidic and alkaline solutions is shown below. Under acidic conditions water binds to the surface with the irreversible removal of one electron and one proton to form a platinum hydroxide. [4]
It is manufactured by treating an aqueous solution of potassium carbonate or potassium hydroxide with carbon dioxide: [1] K 2 CO 3 + CO 2 + H 2 O → 2 KHCO 3. Decomposition of the bicarbonate occurs between 100 and 120 °C (212 and 248 °F): 2 KHCO 3 → K 2 CO 3 + CO 2 + H 2 O. This reaction is employed to prepare high purity potassium carbonate.
The most common Lewis bases are anions. The strength of Lewis basicity correlates with the pK a of the parent acid: acids with high pK a 's give good Lewis bases. As usual, a weaker acid has a stronger conjugate base. Examples of Lewis bases based on the general definition of electron pair donor include: simple anions, such as H − and F −
An acidic oxide is an oxide that either produces an acidic solution upon addition to water, or acts as an acceptor of hydroxide ions effectively functioning as a Lewis acid. [1] Acidic oxides will typically have a low pK a and may be inorganic or organic. A commonly encountered acidic oxide, carbon dioxide produces an acidic solution (and the ...