Wurtz-condensation products

Evidently, the types of compound compatible with this mixture are not many, but it has been used successfully for various 1,3-dioxacycloalkanes and hydrocarbons. It must not be used with halogen compounds although chloro- and bromo-alkanes can be dried safely over sodium films, provided that they are initially at least Grignard dry and free of oxygen. In the author s laboratory specimens of CHjClj and MeBr which had been over sodium films under vacuum for several years were analysed and found to contain only traces of the Wurtz-condensation products. 

Riccitiello et al. have synthesized preceramic polymers with Si—B bonds in their backbones by a Wurtz analogous reaction of dialkyldichlorosilanes and boron halides, either with or without adding methyl iodide for the control of molar masses of the condensation products. Most of the polymers obtained are solid, and soluble in hydrocarbons. Even though the Wurtz reaction is not specific, the IR spectra of the polymer clearly indicate that Si—B bonds have formed preferentially, but do not provide any evidence for the presence of Si—Si or B—B bonds. Based on these results the authors suggest that the backbones generated mainly consist of an alternating sequence of Si and B [55-59]. 

That acetio arid condenses rapidly with ethylene oxide was first, noted by Wurtz hjaudf18 -1 1 as early as 1860. Although 2-acet-cixy-ethanol appeared to be the principal product, there were al < form - ... 

On the other hand, to accelerate alcoholysis of NaH and KH in solutions of benzene or THF [22.1] - [2.22] - ctyptands are used (which bind alkaline metal into a rather stable chelate complex) [1004], Quite stable, volatile per-fluorotert-butoxides were first obtained in reactions of LiH or NaH with (CF3)3COH they distill at atmospheric pressure at 218 and 232°C, respectively [467] (the application of metals would presumably lead in this case to condensation of Wurtz type). Li and Na hydrides are used as cheaper than metal raw materials for production of the corresponding metal alkoxides. In particular it has been suggested that the equipment used in production of MH could be cleaned from its residue by the mixture ofEtOH and the aromatic hydrocarbon (40 to 60% by volume). After hydrogen evolution is completed the solvent is eliminated under vacuum at < 90°C the residue is MOEt with the content of the main product > 98% [342],... 

Dehalogenation.1 Cuprous chloride dissolves in DMSO to give a colorless clear solution, which reacts with certain benzylic and allylic halides to give products of Wurtz-type condensation. 

Polycarbosilanes can be obtained by a Wurtz-like condensation of dichloro-silanes in mixture with a dihalomethane. The products obtained in these reactions do contain not only the desired Si-C-Si linkages but also oligosilane units -(SiR2)x- and -(CH2)x- units [93] ... 

One of the most ancient C-C bond transformation in organic chemistry is the useful aldol reaction [1, 2], originally reported by Wurtz in 1872 [lb]. Years before this process was described, Kane discovered the related aldol condensation [la]. In this case, a,p-unsaturated carbonyl compound was obtained by dehydration of the former aldol product. In the aldol reaction, a nucleophile, generally an enolizable carbonyl compound, reacts with itself or with another carbonyl compound acting as electrophile to give a P-hydroxy carbonyl compound... 

The use of ultrasound allows the direct in situ formation of benzyllithium from benzyl bromide while normally Wurtz coupling predominates with this halide. (See e.g. p. 79 [15]). Condensation, e.g. with acetophenone gives the expected product in 95% yield. Also allylic and vinylic halides undergo clean... 

The nineteenth century was a time when chemists were exploring chemical reactivity with no knowledge of mechanism and with a limited ability to identify products when compared to today s methodology (see Chapter 1, Section 1.1). Nonetheless, many reactions were discovered that are used today, and the structures of the products were accurately determined. L. Chiozza in 1856 (Italy) and Adolphe Wurtz (France 1817-1884) in 1872 reported independent experiments in which an aldehyde was treated with an alkoxide base in an alcohol solvent heated to reflux (heated at the boiling point of the alcohol). When this reaction was cooled to room temperature and treated with dilute aqueous acid at low temperatures, a P-hydroxy aldehyde (known generically as an aldol) was isolated. Because of the type of product formed, this reaction has come to be called the aldol condensation. 

Wurtz examined their oxidation products and thought these resembled silidc and stannic adds, condensed acids formed by loss of water from ortho-acids ... 

Claisen and Claparede [6], and named after the inventors ( Claisen-Schmidt condensation ) [2]. Obviously, Wurtz first recognized [7] the simultaneous presence of aldehyde and alcohol moieties in the aldol 1 resulting from the acid-induced reaction of acetaldehyde, and the reaction vas named after the product it leads to later on (Eq. (1)). 

Since its identification in 1872 by Charles-Adolphe Wurtz and Alexander Borodin, the aldol reaction has found immense synthetic utility in the formation of carbon-carbon bonds. The utility of the aldol reaction, however, was typically limited due to the formation of various condensation adducts. The desire to reduce the formation of unwanted byproducts led researchers to investigate modifications to the classical aldol model. One theme which emerged from studies to overcome the limitations to the aldol reaction was the incorporation of more powerful lithium amide bases for the production of kinetic and/or thermodynamic lithium enolates. ... 

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