Acetaldehyde, synthesis using metal

Acetaldehyde, synthesis using metal catalysts, 118-119 Acetoacetate esters, replacement for isocyanates, 13... 

Oxidative dehydrogenation of alcohols is a new approach in the development of industrial processes for the synthesis of aldehydes and ketones [103-105], In this regard, the technologically most suitable is the method of acetaldehyde synthesis in the presence of melted vanadium oxide, alkaline metals with promoting additives, alkaline metal sulfates or chlorides as catalysts [105], The target product yield equals 65.9% per used alcohol at 69.2% conversion. The disadvantage of the method is the relatively low yield of the target product... 

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequendy used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkaU catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonittile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkaU metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Grignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

Cyclopentadiene itself has been used as a feedstock for carbon fiber manufacture (76). Cyclopentadiene is also a component of supported metallocene—alumoxane polymerization catalysts in the preparation of syndiotactic polyolefins (77), as a nickel or iron complex in the production of methanol and ethanol from synthesis gas (78), and as Group VIII metal complexes for the production of acetaldehyde from methanol and synthesis gas (79). 

Oxygen has major uses in the chemical industry too. It is used to oxidize methane, ethylene, and other hydrocarbons. Oxidation of methane produces synthesis gas. Ethylene oxidation yields products such as ethylene oxide, acetaldehyde, and acetic acid. Oxygen also is used in making many commercial inorganic compounds including various metal oxides, oxoacids, and 0x0-salts. 

A group at the Academy of Sciences in Moscow 197) has synthesized chiral threonine. Derivatives of cyclic imino acids form copper complexes with glacine and carbonyl compounds. Hydroxyethylation with acetaldehyde and decomposition of the resulting complexes produced threonine with an optical purity of up to 97-100% and with threo/allo ratios of up to 19 1 197). The chiral reagents could be recovered and re-used without loss of stereoselectivity. The mechanism of this asymmetric synthesis of amino acids via glacine Schiff base/metal complexes was also discussed 197). 

Both acid and metal catalysis are usually required to accomplish hydration of alkynes to yield carbonyl compounds.34 The addition is usually regioselective, allowing for conversion of terminal alkynes to ketones. Hydration of acetylene to produce acetaldehyde used to be an industrially significant process but was replaced by the Wacker synthesis. 

Cleavage of thf by LiR occurs with formation of ethylene and the metal enolate of acetaldehyde (ethenolate), the simplest enolate anion. For example, Li(OCH=CH2) results from the reaction of LiR (R = n-Bu , t-Bu ) with thf and it has been used in the synthesis of other metal enolato complexes. 

Additions to nonactivated olefins and dienes are important reactions in organic synthesis [1]. Although cycloadditions may be used for additions to double bonds, the most common way to achieve such reactions is to activate the olefins with an electrophilic reagent. Electrophilic activation of the olefin or diene followed by a nucleophilic attack at one of the sp carbon atoms leads to a 1,2- or 1,4-addition. More recently, transition metals have been employed for the electrophilic activation of the double bond [2]. In particular, palladium(II) salts are known to activate carbon-carbon double bonds toward nucleophilic attack [3] and this is the basis for the Wacker process for industrial oxidation of ethylene to acetaldehyde [41. In this process, the key step is the nucleophilic attack by water on a (jt-ethylene)palladium complex. 

The direct production of acetic acid from synthesis gas [80] instead of methanol as feedstock has demonstrated selectivities up to 80% using rhodium fixed-bed catalysts with Group IIIA-VIIIA promoters and alkaline metals. Other C2 compounds were also formed (acetaldehyde, ethanol, and ethyl acetate) [129],... 

Synthesis of pyridines from acetaldehyde, formaldehyde and ammonia in the gas phase was studied with regard to metal catalyst and Si/Al ratio of the support (94CL59>. Best conditions were Si/Al = 30 to 120 and use of Tl Pb Co or Zn catalyst. The total yield of pyridines based on aldehydes was 61%. 

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