Alcohols alkoxides

Similarly, thioalcohols and thiophenols react with isocyanates to form thiocarbamates. Although these reactions are generally found to be much slower than that of the corresponding alcohol, alkoxide catalysts have successfully been used to provide moderate levels of rate enhancement (68). 

In 2,4-disubstituted quinazolines, the 4-position reacts fastest with nucleophiles, generally even when the 4-substituent is a poorer leaving group. 2,4-Dichloroquinazoline undergoes mono-substitution at the 4-position with alcoholic alkoxides (25°, 2 hr, 80-98% yield), phenolic phenoxide (20°, 16 hr, 50% yield), aqueous hydroxide (30°, 3 hr), alcoholic methylmercaptide (20°, exothermically), alkylamines (20°, 10-60 min, 100%... 

V,iV-Dimethylfuro 2,3-Z> quinoxaline-3-carboxamide (556) (as hydrochloride) in hot acidic or alkaline media for 1 h gave 3-methyl-2(l//)-quinoxalinone (555) in 60% or 95% yield, respectively 342 588 In contrast, the same amidic substrate (556) in hot alcoholic alkoxide afforded 3-ethoxycarbonylmethyl- (557, R = Et) or... 

Monohaloalkanes react with alkalis to form alcohols, with alcoholic alkoxides to form ethers and with ethanolic cyanides to form nitriles. 

In a very similar way, hydroxy functionalized ATRP initiators such as 2,2,2-tribromoethanol can be used for the simultaneous polymerization of eCL and MMA (Scheme 25) [83]. Purposely, the ROP of eCL is promoted by Al(OfPr)3 added in catalytic amount so that the rapid alcohol-alkoxide exchange reaction (see Sect. 2.4) activates all the hydroxyl functions. In order to avoid initiation by the isopropoxy groups of Al(0/Pr)3. The in-situ formed zPrOH is removed by distillation of the zPrOH/toluene azeotrope. On the other hand, the ATRP of MMA is catalyzed by NiBr2(PPh3)3. The two aforementioned one-step methods provide block copolymers with controlled composition and molecular weights, but with a slightly broad MWD (PDI=1.5-2). 

For secondary or tertiary alcohols, the yields are improved by adding the alcohol-alkoxide solution dropwise to a solution of trichloroacetonitrile and ethyl ether at 0°. 

A number of contradictory views have been published concerning the structure of adsorbed alcohols and the nature of adsorption sites (for review see ref. 69). Experimental evidence from IR investigations has shown that, on alumina, alcohols form several surface complexes of very different chemical natures (e.g. refs. 31, 32, 117, 133—137) (i) alcohol molecules weakly bonded to the surface, very probably by hydrogen bonds (I) (such complexes are sometimes denoted as physically sorbed alcohols) (ii) surface alkoxides (alcoholates) (II) (iii) surface carboxy-lates (III). Less certain is the existence of species with partial double bonds or of ketone-like species. The formation of the various surface complexes is dependent on the structure of the alcohol. For examples, weakly bonded species (I) have been found with all alcohols, alkoxides (II) mostly with primary alcohols, sometimes also with secondary alcohols, but have never been reported for tertiary alcohols. 

Thus, 5-ethyl-2-thienylthioacetic ester (167) was converted to the aldehyde-ester derivative (168) using the Vilsmeier reaction. The action of alcoholic alkoxide on (168) led to the cyclized product (169). Subsequent decarboxylation gave the thieno[2,3-6 ]thiophene derivative (71 Scheme 55) (76AHC(19)123). 

Solubility of LiCl in MeOH, EtOH, and"BuOH is 30.4, 19.6, and 13.9%, respectively. That is why after refluxing of the reaction mixture and washing off the precipitate with alcohol, alkoxides free from LiCl are obtained. However, this reaction in many cases is also complicated by formation of bimetallic complexes. Formation of stable intermediate complexes is especially characteristic when LiOR is applied for alkoxylation. Thus Li4Y40(0Bu )12Cl2 was isolated in reaction of YC13 with 2 mols of LiOBu (i.e., on lack of OR-ligands) [553]. 

There are many producers in Europe with similar ranges of products including some based on C13 alcohols e.g. Lansurf AE35. Lankem also has a range based on C16 18 alcohols with 4, 19 and 35 mol of ethylene oxide added e.g. Lansurf AE735. In addition Lankem produces random alcohol alkoxides such as Lansurf AEP66, which are based on Ci2—15 alcohols with a random mix of ethylene and propylene oxides. 

In the 2,3-dihydro-5-oxo-5Ff-oxazolo[3,2-c]pyrimidinium salt (207) there are three sites for reactions with nucleophilic reagents, viz. C-2, C-8a and C-7. Products resulting from attack at C-2 are observed with DMSO, water, alcohols, benzoate, chloride, diethylamine and pyridine. Products resulting from attack at C-8a are observed with water, hydroxide, alcohols, alkoxide and isopropylamine. Diethylamine also causes attack at C-7 of the cation, which results in cleavage of the pyrimidine ring (75JOC1713). 

Note This reaction is usually done with alcoholic alkoxide but an alcohol alone may be used (over a much longer period) if some alkoxide-sensitive passenger group is present. 

The electronegative metals usually form unstable alkoxides that tend to polymerize rapidly to form [-M(OR)2-0-] . Alkoxides are easily solubilized in alcohols. Alkoxide precursors must be kept fme of water to avoid hydrolysis. Hydrolysis is the first step in the reaction of alkoxides to form gel networks. This is difficult because alkoxide solutions easily absorb water finm the atmosphere. 

Amidinium salts (obtainable by various methods, compare Section 2.1.2.5) which are not peralkylated at nitrogen are converted to amidines by treatment with strong bases, e.g. aqueous alkali metal hydroxides, alcoholic alkoxides, tertiary amines etc. As already mentioned it is not difficult to alkylate amidines (see Section 2.7.2.5.4), thus by subsequent alkylation and deprotonation reactions amidines can be synthesized carrying the desired substituents at nitrogen, e.g. (308 Scheme 47). A series of trisubstituted formamidines have been prepared by reaction of anilines with the azavinylogous form-amidinium salt (309). ... 

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