Thioacetaldehyde

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. 

The next debate in the literature was whether these molecules have C2v or Cs symmetry. The nuclear motion of a C2v symmetric structure would be described by a single-well potential (see Figure 10). The alternative is a rapid interconversion of two valence tautomers, each of Cs symmetry. This would occur via the C2v structure as transition state (see Figure 11). In this case the motion of the central sulfur would be described by a double-well potential, and dioxathiapentalene and trithiapentalene would be misnomers for (3//-l,2-oxathiol-3-ylidene)acetaldehyde 180 and (3/7-1,2-dithiol-3-ylidene)thioacetaldehyde 181. One advantage of C2v symmetry is aromatic stabilization from the 1071 electrons <2001CRV1247>. The alternative Cs symmetry has the advantage of avoiding a hypervalent sulfur. 

In view of the specific nature of the whole process it appeared interesting to investigate whether the reduction of thioacetaldehyde to mercaptan could also be accomplished with cell-free enzyme solutions. Neuberg and Nord found that yeast maceration juice effects this hydrogenation (see p. 79). 

This method of phytochemical reduction may also be extended to homologs of thioacetaldehyde. In this way Nord converted the ammonia derivatives of n-thiobutyraldehyde and thioisovaleraldehyde to n-butyl and isoamyl mercaptans, respectively. 

Two different thioacetaldehyde complexes (31 and 32) were obtained from 30 by a deprotonation/reprotonation sequence depending on the base used (KOH/CH2Cl2 or KO Bu/THF) (Scheme 12).163... 

Although this route also seemed to be suitable for rhodium compounds, the readily accessible complex [Rh(CHClMe)Cl(PPr,3)(775-C5H5)] did not afford the thioacetaldehyde complex when treated with NaHS but rather the vinyl complex [Rh(CH = CH2)Cl(PPri3)(775-C5H5)].55... 

The alkylation of the zirconocene thioacetaldehyde complex 81a with excess Mel also yielded an 5-methylated product (122) [Eq. (26)]. In contrast, the protonation by methanol in excess gave ethanethiol, trimethyl-phosphine, and dimethoxyzirconocene, presumably via a [Zr(OMe)(SEt) (t75-C5H5)2] intermediate.70... 

The enolate anions of thioacetaldehyde and thioacetone were generated in a flow tube by rapid (presumable) E2 elimination reactions of F with the appropriate sulphide (equations 36 and 37, respectively)181. 

Thioacetaldehyde. Maier and coworkers obtained this compound by flash pyrolysis of allyl ethyl sulfide in an argon matrix182. Its IR spectrum does not show a characteristic C=S stretching band. A comparison of the observed spectrum with the calculated one [the MP2/6-31G(d) level] allowed the identification of the molecule and further showed the extensive coupling between the normal C=S stretching mode and other normal modes. 

Flash pyrolysis in an argon matrix of allylethylsulfide afforded thioacetaldehyde characterized by comparison of experimental and calculated IR spectra182 (equation 98) (see Section II). 

Only one isolated example of formation of thioketene and thioaldehyde dimolybdenum complexes has been reported507, but in contrast, zirconocene thioacetaldehyde and thiobenzaldehyde complexes, introduced by Buchwald, have been the subject of several studies508, including their application in the synthesis of novel antimony thiametallacy-cles 148509 (equation 156). Compound 146 was generated in situ and, after reaction with alkynes, gave rise to metallacycles 147 which, by treatment with SbCR, afforded 148. 

Alternatively, thiophenes have been accessed by base induced reactions involving thioacetaldehyde dimer and active methylene compounds under microwave irradiation, as illustrated by synthesis of 2-aminothiophene-3-carbonitrile 7 <07TL5261>. 

The Franck-Condon factors determination is of special interest when the two electronic states, involved in the transition exhibit very different geometries. This is especially the case of electronic transition in the valence shell such as n — tt, which induces conjugation change, as well as geometrical change, in the molecular system. This phenomenon was studied in the fluorescence spectra of acetaldehyde and acetone [62,63], and in the phosphorescence spectra of thioacrolein and thioacetaldehyde [64,65] and thioacetone [66]. 

To classify the torsional states of both electronic states with different structures according to the irreducible representations of a same group seems to be difficult. It can be easily done, however, into the NRG formalism. So, the torsional states of both electronic states of thioacetaldehyde can be classified into the representations of a NRG which presents the following characteristic ... 

Simulated annealing calculations were performed to acquire the mechanisms of thermolysis of thiirane and thiiranium cation <2002JMT71>. The AMPAC 6.55 package along with AIMl and SAMI methods were used to estimate structures, which were then used as starting points for further ab initio calculations. Critical points were confirmed by calculation of the vibrational frequencies. The primary reactions thiirane 19 —> S-f ethene, thiirane—> vinyl thiol 20, and thiirane ethanethial (thioacetaldehyde) 21 were examined for thermolysis of thiirane Scheme 1. Many secondary reactions were also examined. The simulated annealing method was predicted to be very useful in the future for the study of competing chemical reactions. 

Dimethylthietane yields an ion, C2H4S ", believed to be the ion-radical of thioacetaldehyde. The mass spectrum of 3-hydroxythietane shows the loss of vinyl alcohol from the parent ion to give CH2S ". ... 

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