REARRANGEMENT STUDIES WITH C14: XIV. THE REACTION OF 2-p-ANISYLETHANOL-1-C14 WITH THIONYL CHLORIDE

1963 ◽  
Vol 41 (3) ◽  
pp. 620-624 ◽  
Author(s):  
C. C. Lee ◽  
Donna Newman ◽  
D. P. Thornhill
Keyword(s):  
Thermal Decomposition ◽  
Thionyl Chloride ◽  
Ion Pair ◽  
Excess Thionyl Chloride

Reaction between 2-p-anisylethanol-1-C14 and thionyl chloride was carried out with pyridine, n-hexane, toluene, dioxane, or excess thionyl chloride as solvent. The 2-p-anisylethyl chloride obtained showed rearrangement of the C14 label from the C-1 to C-2 positions ranging from about 0.5% for the reaction in pyridine to about 46% for the reaction in excess thionyl chloride. The results can be explained on the basis of varying degrees of involvement of the ethylene-p-methoxyphenonium chlorosulphite ion pair, thus supporting the suggestion that thermal decomposition of alkyl chlorosulphites to give chlorides may be considerably ionic in character.

REARRANGEMENT STUDIES WITH 14C: XIX. THE REACTION OF 2-PHENYL-1-14C-ETHANOL WITH THIONYL CHLORIDE

1964 ◽  
Vol 42 (5) ◽  
pp. 1130-1136 ◽  
Author(s):  
C. C. Lee ◽  
D. J. Kroeger ◽  
D. P. Thornhill
Keyword(s):  
Thionyl Chloride ◽  
Ion Pairs ◽  
Aqueous Sodium Hydroxide ◽  
Covalent Bonding ◽  
Ion Pair ◽  
Aqueous Sodium ◽  
Carbonium Ion ◽  
Partial Completion ◽  
The Stability ◽  
Excess Thionyl Chloride

The reaction of 2-phenyl-1-14C-ethanol with thionyl chloride in pyridine, dioxane, toluene, or excess thionyl chloride as solvent gave 2-phenylethyl chloride showing, respectively, about 0, 15, 44, and 48% rearrangement of the 14C-label from the C-1 to the C-2 positions. When reactions of 2-phenyl-1-14C-ethauol or 2-p-anisyl-1-14C-ethanol with thionyl chloride in dioxane or excess thionyl chloride were carried only to partial completion and the undecomposed chlorosulphites hydrolyzed by aqueous sodium hydroxide, the recovered alcohols showed only 0.1 to 0.5% isotope position rearrangement. This indicated a lack of return from ion-pairs to isotopically rearranged 2-arylethylchlorosulphite and suggested that the first stage of ionization may involve ion-pairs with structures that will not result in rearrangement on return to covalent bonding, or that the first ion-pair may decompose faster than it can return to reactant. The possibility that rearrangements via rigidly oriented ion-pairs and via the concerted SNi′ mechanism may represent the two extremes of a graded series is discussed. It is suggested that the relative contributions from the ion-pair and from the SNi′ mechanisms will depend on the stability of the carbonium ion as well as on the nature of the reaction solvent.

The Polymerization of Methacrylonitrile. Polymethacrylonitrile

1945 ◽  
Vol 18 (2) ◽  
pp. 267-279 ◽  
Author(s):  
Werner Kern ◽  
Helmut Fernow
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Chloride ◽  
Thionyl Chloride ◽  
Hydroxy Acid ◽  
Raw Materials ◽  
Phosphorus Pentoxide ◽  
Slight Excess ◽  
Starting Point ◽  
Pure Compounds ◽  
Ready Availability

Abstract As the starting point for the preparation of methaerylonitrile, acetonecyanohydrin (α-hydroxybutyronitrile) was chosen because of its ready availability. β-Hydroxybutyronitrile should likewise be well suited for the purpose, but, because of the difficulties involved in its preparation, it was not utilized in the work. The removal of water can be accomplished in various ways. (1) Phosphorus pentoxide does not give such smooth results as it does with ethyleneeyanohydrin, but the reaction can be carried out successfully by centrifuging and the addition of quinoline. Under the same conditions acetaldehydeeyanohydrine (lactonitrile) yields no acrylonitrile. (2) The thermal decomposition of acylated hydroxy-acid derivatives can be applied to acetonecyanohydrin, but this method of preparation is difficult to carry out on a laboratory scale. (3) Removal of water can be carried out very smoothly with thionyl chloride. In addition to methacrylonitrile, α-chloroisobutyronitrile is formed, and from the latter more methacrylonitrile can be obtained by scission of hydrogen chloride. In this procedure, it is highly important to use pure raw materials, especially thionyl chloride, for with pure compounds the yields are higher. It is likewise advantageous to use a slight excess of thionyl chloride.

Mechanism of SNi reactions. The effect of the base strength of the anionic fragments

1978 ◽  
Vol 56 (19) ◽  
pp. 2582-2589 ◽  
Author(s):  
D. J. Verrinder ◽  
M. J. Hourigan ◽  
J. M. Prokipcak
Keyword(s):  
Thermal Decomposition ◽  
Optical Activity ◽  
Ion Pair ◽  
Decomposition Rates ◽  
First Order ◽  
First Order Kinetics ◽  
Cyclic Mechanism ◽  
Base Strength ◽  
Oxygen Bond ◽  
Anionic Fragment

The kinetics and stereochemical aspects of the thermal decomposition of aralkyl carbonates, thiocarbonates, and carbamates were examined. The rates for the decompositions as well as the rates of loss of optical activity followed first-order kinetics. The decompositions appear to involve the heterolysis of the aralkyl–oxygen bond followed by the breakdown of the subsequent ion pair via a cyclic mechanism. However, it was found that this ion pair could return to covalency without completely decomposing to products leading to the racemization of the starting materials. This type of racemization occurred more readily in the case of the carbamates than in the thiocarbonates and carbonates. The dependence of the decomposition rates and the loss of optical activity on the nature of the hetero atom of the anionic fragment of the starting material is discussed.

The chemistry of N,N′-dimethylformamidine. I. Formation from potassium methylamide and its thermal stability

1978 ◽  
Vol 56 (11) ◽  
pp. 1455-1462 ◽  
Author(s):  
James D. Halliday ◽  
E. Allan Symons ◽  
J. Douglas Bonnett
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Potassium Salt ◽  
Rate Increase ◽  
Ion Pair ◽  
Concentrated Solutions ◽  
First Order ◽  
Pseudo First Order ◽  
Hydride Elimination ◽  
Rate Limiting

The thermal decomposition of methylamine solutions of potassium methylamide (PMA) to form the potassium salt (PDMFA) of N,N′-dimethylformamidine (DMFA) has been studied as a function of PMA concentration at 60 °C. Although concentrated solutions yield normal pseudo-first-order plots (analysis by ultraviolet–visible spectrophotometry), dilute solutions (< 0.05 mol L−1 PMA) show an increase to a new rate after about 20 h reaction.The mechanism for this novel amidine salt synthesis is discussed in terms of rate-limiting β-hydride elimination from the PMA ion pair. The relatively sharp rate increase with time for the low concentration runs may arise from a slow build up of one or more intermediates. The resulting inverse dependence of kobs on PMA concentration is probably related to ion pair–dimer association phenomena.Pure DMFA has been produced by this reaction, and its thermal stability examined. DMFA decomposes above 100 °C to form bis-N-(N′-methylmethylenimine)methylamine and methylamine; the series of equilibria involved have been shown to be reversible.

On the Reaction of Deacetylvindoline with Thionyl Chloride

2000 ◽  
Vol 65 (5) ◽  
pp. 789-796 ◽  
Author(s):  
Josef Hájíček ◽  
Vladimír Hanuš
Keyword(s):  
Thionyl Chloride ◽  
Mass Spectra ◽  
2D Nmr ◽  
Single Product ◽  
Complex Transformation ◽  
Excess Thionyl Chloride

Reaction of deacetylvindoline (2) with excess thionyl chloride gave rise to hexacyclic 6,10-dichloro-6,17-epithio-11-methoxy-1-methyltabersonine (4) as a single product in 43.5% yield. The structure was deduced from 1H and 13C 1D and 2D NMR experiments as well as from mass spectra. A tentative mechanism of this complex transformation was also proposed.

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