An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO^–, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands. . Alkoxides, although generally not stable in protic solvents such as water, occur widely as intermediates in various reactions, including the Williamson ether synthesis. Transition metal alkoxides are widely used for coatings and as catalysts. In the field of chemistry, in the Brønsted-Lowry (protonic) theory of acids and bases, a conjugate base is the basic member, X-, of a pair of compounds that differ only by the presence or absence of a proton at a certain position. ... Functional group of an alcohol molecule. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... A base in chemistry is a chemical substance which has a free pair of electrons to bind a hydrogen ion commonly referred to as a proton (IUPAC definition). ... In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ... In chemistry a protic solvent is a solvent that carries hydrogen bond between an oxygen as in a hydroxyl group or a nitrogen as in an amine group. ... Williamson ether synthesis was developed by Alexander Williamson in 1850. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... It has been suggested that this article or section be merged into Catalysis. ...

Enolates are unsaturated alkoxide derived by deprotonation of a C-H bond adjacent to a ketone or aldehyde. The nucleophilic center for simple alkoxides is located on the oxygen, whereas the nucleophilic site on enolates is delocalized - both carbon and oxygen are basic. Enol (or, more officially, but less commonly: alkenol) is an alkene with hydroxyl group on one of the carbon atoms of the double bond. ... Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ... An aldehyde. ...

Phenoxides represent a special class of anions that are closely related to alkoxides, except the organic substitutent is a derivative of benzene. Phenol is significantly more acidic than a typical alcohol, thus phenoxides are correspondingly less basic and less nucleophilic. They are however often easier to handle and afford derivatives that are more crystalline than the alkoxides. Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ...

Preparation

From reducing metals

Alkoxides can be produced by several routes starting from an alcohol. Highly reducing metals react directly with alcohols to give the corresponding metal alkoxide. The alcohol serves as an acid, and hydrogen is produced as a by-product. A classic case is sodium methoxide produced by the addition of sodium metal to methanol: Functional group of an alcohol molecule. ... Acidity redirects here. ... This article is about the chemistry of hydrogen. ...

CH₃OH + Na → CH3ONa + 1⁄2H₂

Other alkali metals can be used in place of sodium, and most alcohols can be using in place of methanol. The alkali metals are the series of elements in Group 1 (IUPAC style) of the periodic table (excluding hydrogen in all but one rare circumstance): lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). ...

From electrophilic chlorides

The tetrachloride of titanium reacts with alcohols to give the corresponding tetraalkoxides, concomitant with the evolution of hydrogen chloride: R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ...

TiCl₄ + 4 (CH₃)₂CHOH → Ti(OCH(CH₃)₂}₄ + 4 HCl

The reaction can be accelerated by the addition of a base, such as a tertiary amine. Many other metal and main group halides can be used instead of titanium, for example SiCl₄, ZrCl₄, and PCl₃. Titanium tetrachloride (or titanium(IV) chloride) is the chemical compound with the formla TiCl4. ... Titanium isoproxide is a chemical compound with the formula Ti{OCH(CH3)2}4. ... Ammonia Amines are organic compounds containing nitrogen as the key atom in the amine functional group. ...

By metathesis reactions

Many alkoxides are prepared by salt-forming reactions from a metal chloride and sodium alkoxide:

NaOR + MCl_n → M(OR)_n + n NaCl

Such reactions are favored by the high stability of the NaCl, and separation of the product alcoxide is simplified by the fact that NaCl is insoluble in common organic solvents. The lattice energy, or lattice enthalpy, of an ionic solid is a measure of the strength of bonds in that ionic compound. ...

By electrochemical process

Many alkoxides can be prepared by anodic dissolution of the corresponding metals in water-free alcohols in the presence of electroconductive additive. The metals may be Sc, Ga, Y, La, Ln, Si, Ti, Ge, Zr, Hf, Nb, Ta, Mo, W, Fe, Co, Ni, Re, etc. The conductive additive may be lithium chloride, quaternary ammonium halogenide, or other. Some examples of metal alkoxides obtained by this technique: Ti(OC₃H₇-iso)₄, Nb₂(OCH₃)₁₀, Ta₂(OCH₃)₁₀, [MoO(OCH₃)₄]₂, Re₂O₃(OCH₃)₆, Re₄O₆(OC₃H₇-iso)₁₀, etc.

Properties

Most metal alkoxides hydrolyse irreversibly upon contact with water, according to the following equation:

Ti(OCH₂CH₃)₄ + 2 H₂O → TiO₂ + 4 HOCH₂CH₃

By controlling the stoichiometry of steric properties of the alkoxide, such reactions can be arrested leading to metal-oxy-alkoxide clusters. Other alcohols can be employed in place of water. In this way one alkoxide can be converted to another, a process sometimes called transesterification. Sodium methoxide, for example, is used in the large scale synthesis of bio-diesel, an example of a transesterification reaction. The position of the equilibrium can be controlled by the acidity of the alcohol; for example phenols typically react with alkoxides to release alcohols, giving the corresponding phenoxide. More simply, the trans-esterification can be controlled by selectively evaporating the more volatile component. In this way, ethoxides can be converted to butoxides, since ethanol (b.p. 78 °C) is more volatile than butanol (b.p. 118 °C). Bus running on soybean biodiesel. ...

Illustrative alkoxides

• titanium isopropoxide, used as a catalyst in organic synthesis and a precursor to TiO₂.
• aluminium isopropoxide, used as a reagent in organic synthesis.
• tetraethylorthosilicate, used as a precursor to SiO₂.