Metal alkoxides sodium methoxide

To complete the synthesis of keto disaccharide 16, the cyclic carbonate must be cleaved and the C-4 hydroxyl group must be oxidized selectively. With respect to the former objective, it is well known that a metal alkoxide (e. g. sodium methoxide) can easily... 

Ring closure of a 2-methoxyphenyl derivative of propanol to a chroman has also been achieved. Treatment of the aryloxazoline (259) with sodium hydride yielded the chroman (260) (81JOC783). The intramolecular nucleophilic displacement of the o-methoxy group is promoted through oxazoline activation and proceeds through an addition-elimination sequence. The initial attack involves coordination of the metal alkoxide to both the oxazoline moiety and the methoxy group, and aromatization follows with displacement of methoxide ion (Scheme 67). Hydrolysis of the oxazoline moiety to a carboxyl group has been accomplished. 

There have been few investigations of the reactions of polyhydroxy compounds with alkali metal alkoxides in nonaqueous media at room temperature.. Percival" reported the preparation of D-glucose-NaOEt and D-glucose NaOMe by treating d-glucose with sodium ethoxide, and penta-O-acetyl-D-glucopyranose with sodium methoxide, respectively. The adducts were dried under vacuum at 60° for 24 hours, a treatment which would make the presence of any significant proportion of alcohol of solvation unlikely. Any traces of moisture in the preparative medium preclude the formation of an aJkoxide adduct. 

Alkali metal alkoxides such as KOH, NaOH, and CH3ONa are the most effective catalysts in alkali-catalyst transesterification. When using KOH, NaOH, and CH3ONa alkali-catalyst for FAME conversion, the active catalytic species were the methoxide anion (CH 0 ), formed by the reaction between methanol and hydroxide ions of KOH and NaOH. In addition, the methoxide anion was formed by dissolution of sodium methoxide. Sodium methoxide causes the formation of several byproducts, mainly sodium salts, that have to be treated as waste and additionally require high-quality oil (16). However, KOH has an advantage because it can be converted into KOH by reaction with phosphoric acid, which can serve as a fertilizer. Since KOH is more economical than sodium methoxide, it is the preferred choice for large-scale FAME production process. 

Replacement of chlorine with alkoxy groups generally proceeds by heating with alkali metal alkoxides. 2,8-Dimethoxypurine (1) is obtained when 2,8-dichloropurine is treated with sodium methoxide. ... 

The preparation of orthoformic acid esters from chloroform and alkali metal alkoxides is a long known procedure, " which can be performed under phase transfer catalysis. If small amounts of alcohol are present in the phase-catalyz process, cyclopropanes (372 Scheme 67) can be produced by aHHifinn of dichlorocarbene to l,2-dialkoxy-l,2-dichloroethylenes, which are thought to be intermediates. " Al-kenes of this kind, e.g. (373 equation 176), have been observed as byproducts in the synthesis of tri-r-butylorthoformate from chlorodifluoromethane or dichlorofluoromethane and potassium r-butoxide. Trimethoxyacetonitrile was prepared from trichloroacetonitrile and sodium methoxide. ... 

Reversibility of the insertion of CO2 provides a convenient route to some metal alkoxides by a process generalized earlier [reaction (g), 11.5.1]. For example, tributyl-tin(IV) methoxide can be prepared by treating tributyltin(IV) chloride with sodium methoxide, but it can be difficult to separate the finely divided sodium chloride that is formed. It is easier to heat bis(tributyltin) oxide with methyl carbonate tributyltin(lV) methoxide and methyl tributyltin carbonate are first formed in an exchange reaction ... 

Most metal chlorides undergo only partial metathetical halide/alkoxide exchange upon reaction with alcohols or no reaction at all even at elevated temperatures. The metal alkoxide chlorides thus obtained, MClx(OR), have not been used in sol-gel processing (see, however. Section 7.10.3.3.2). In order to achieve the preparation of homoleptic metal alkoxides from metal chlorides basic conditions are essential in order to trap the liberated HCl. This can be achieved by reaction of metal chlorides with alcohols in the presence of a base such as ammonia or, less often, trialkylamines or pyridine (Equation (11a)). The base also increases the equilibrium concentration of alkoxide ions, which are a more powerful nucleophile for reaction with the metal chloride than the parent alcohol. For this reason the use of alkali alkoxides (M OR), mostly lithium, sodium, or potassium alkoxides, proves to be more successful (Equation (11b)). The use of LiOR has advantages for the preparation of insoluble metal methoxides because LiCl is soluble in methanol and is thus easily separated from insoluble metal alkoxides. 

Alkoxide ions are somewhat stronger bases than is the hydroxide ion. In addition to sodium methoxide, the following metal salts of alcohols are commonly used in organic... 

Alkoxide ions are nearly the same or somewhat stronger bases than the hydroxide ion. In addition to sodium methoxide, the following metal salts of alcohols are commonly used in organic reactions requiring a strong base in a nonaqueous solvent, as, for example, sodium ethoxide in ethanol and potassium ffrf-butoxide in 2-methyl-2-propanol (fert-butyl alcohol). 

Alkoxide of alkali metal Sodium methoxide, potassium... 

Despite the lack of selectivity, some structured Upid-hke products have been synthesized by chemicals methods. The catalyst most often used for chemical interesterification of triacylglycerols or for alcoholysis between triacylglycerols and fatty acids is sodium methoxide, which is more active than other base, metal or acid catalysts. In general, sodium alkoxides are easy to use as catalysts. They are inexpensive, active at relatively low temperatures (50-90 ), and are effective at low concentrations. Although no regioselectivity or fatty acid selectivity occurs, the chemically synthesized commercial products listed in Table 2 contain sTAG with the desired nutritional function. 

The first attempts to produce a graft copolymer of poly(amino acids) onto the natural polymers, such as cellulose, starch, and their derivatives, were carried out by Zilka and Avny in 1965. Sodium methoxide was known to be an initiator of NCA polymerization. Therefore, they proposed to use alkoxide derivatives of polysaccharides as macroinitiators for the graft copolymerization of NCA s of a-amino acids. All known methods for production of alkoxide derivatives of natural polymers, such as the reaction of polyhydroxy polymers with sodium metal in liquid ammonia, or exchange reactions between lower alkoxides and polyhydroxy polymers, - were unsatisfactory for the subsequent graft copolymerization of NCAs, because any residual base would lead to homopolymerization. In addition, alkoxide derivatives of cellulose acetate and nitrocellulose could not be obtained by these conventional methods due to chemical degradation. Zilka et al., finally found that the reaction of alkali metal naphthalenes [20] with polyhydroxy polymers in either... 

This reaction occurs at hi pressure (810 MPa) in the presence of a catalyst, such as sodium methoxide, at low temperature (80°C) [87]. The effects of various alkali metal alkoxides has been investigated, and the activity of the catalyst has been shown to increase with increasing ionization potential of the metal [94]. From kinetic studies it has also been shown that both C02 and H2Q react with the catalyst, resulting in a reduced reaction rate. The effect of C02 is twice as severe as that of water [95],... 

Here, the methoxide ion, CHjOn is the nucleophile. Alkoxides are formed when an alkali metal, such as sodium or potassium, is added to an alcohol. For example, when potassium is added to methanol, potassium methoxide is formed ... 

RO M+) alkoxide ion. An ionic compound formed by removal of hydrogen ions from the hydroxyl group in an alcohol using reactive metals, c.g. sodium. For example, potassium metal reacts with methanol (CH OH) to produce potassium methoxide (KOCH3). 

Many different types of bases are used in organic chemistry. Common inorganic bases include the anions of weak bases such as water and ammonia (OH and NH2 ). Similar deprotonation of alcohols leads to the alkoxide bases (RO ). Methoxide (MeO ), ethoxide (EtO ), and ferf-butoxide (Me3C-0 ) are very common and are often used in the alcohol solvents from which they were made (methoxide in methanol, tert-butoxide in ferf-butanol, etc.). The bases used to deprotonate water (p fa = 15.8) or alcohols (pATa 18) are sodium hydride (NaH), potassium hydride (KH), sodium and potassium hydroxide (NaOH, KOH), sodium metal (Na°),... 

An interesting and useful derivative of an alcohol is the alkoxide ion, RO , a deprotonated form of the alcohol. The alkoxide ion is formed by the reaction of sodium or potassium metal with the alcohol. For example, the methoxide ion, CHaO , is produced in the following reaction ... 

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