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Synthesis of benzyl thiol

  • 02.06.2019
Synthesis of benzyl thiol
The preferred language metal hydrosulfide salt is the sodium salt. The outreach is carried out under challenging pressure in a closed reactor in two sides. This invention is concerned with such a sports.

To this is added an equal volume of ethyl alcohol and the reaction mixture is resaturated with the hydrogen sulfide. Finally, a quantity of benzyl chloride dissolved in alcohol is added. The mixture is allowed to stand in the cold, with frequent shaking for 4 days, and kept cold to prevent as much as possible the oxidation of the mercaptan to the disulfide and the formation of the monosulfide, which, it is disclosed, takes place readily at high temperatures.

A conventional process for making benzyl mercaptan, as disclosed in U. STR2 A problem which occurs in this reaction, however, is that significant quantities of benzyl sulfide are produced as a by-product. This reduces the yield of benzyl mercaptan and increases the need for purification of the product which is produced. It would be advantageous, therefore, to find a process for the production of benzyl mercaptan which minimizes the quantity of benzyl sulfide by-product formed during the reaction and optimizes the percent yield of the desired benzyl mercaptan obtained.

This invention is concerned with such a process. The preferred benzyl halide for use in the process of the invention is benzyl chloride. Benzyl bromide can be used, but it is more expensive than benzyl chloride.

The preferred alkali metal hydrosulfide salt is the sodium salt. Other salts which can be used include the potassium salt. The process as described above results in benzyl mercaptan of high purity and yield being obtained. There are three elements in the above-described process which are essential to the practice of this invention. The first has to do with the temperature adjustments carried out during the period of the reaction.

Although conducting the reaction of lower temperatures leads to reduced levels of benzyl sulfide impurity, the reaction time becomes excessive. Under these conditions, the level of unreacted benzyl chloride can be reduced to a ow level without appreciably increasing the benzyl sulfide level. The effects of the reaction temperature on benzyl sulfide by-product content in the benzyl mercaptan product are shown in the Table below, wherein a series of runs are tabulated.

In each of these reactions, the reactants were benzyl chloride and sodium hydrosulfide. Under these conditions, approximately 97 weight percent pure product was obtained upon cooling and phase separation.

Another critical factor in carrying out the process of the invention is to conduct the reaction in the presence of a hydrogen sulfide atmosphere. The hydrogen sulfide atmosphere should be a static hydrogen sulfide atmosphere, which can be maintained by adding a strong acid such as HCl to the reaction solution. This strong acid results in a hydrogen sulfide gas being generated, which is effective in maintaining a hydrogen sulfide atmosphere over the reaction solution.

Higher concentrations of hydrosulfide salt extend the reaction time by a factor of 3 or more. Over the course of the reaction the quantity of hydrosulfide salt will diminish. The criticality of the hydrosulfide salt concentration in the solution is demonstrated in accordance with the following Table, which represents a series of reactions which were conducted at various sodium hydrosulfide concentrations. Run Temp. Time Prod. Other solvents can be added, such as methanol, toluene or glycerol.

In general, an excess of sodium hydrosulfide is used to react with benzyl chloride in the process of the invention. Sodium hydrosulfide can be prepared by adding hydrogen sulfide to a sodium hydroxide solution or can be purchased commercially.

As previously indicated, a strong acid, such as aqueous hydrochloric acid, can be used to produce the hydrogen sulfide atmosphere, by adding the acid to the slightly larger excess of sodium hydrosulfide in solution. Preferably, about 0. The acid can also serve to adjust the pH of the solution to insure that the minimum amount of disodium sulfide is present. An economically more attractive synthetic route is the nucleophilic substitution of the chlorine atom in benzyl chloride by an alkaline sulfhydrate, ammonium sulfhydrate or an amine sulfhydrate.

This reaction, generally carried out in an alcoholic medium, has long been known: C. Marcker, Liebigs Ann. Zinner, Chem. Bittell et al, J. These references are hereby incorporated by reference. According to U.

Indeed, the separation of benzyl chloride by distillation from crude benzyl mercaptan is very difficult. On the other hand, the formation of byproducts benzyl sulphide and incidentally benzyl disulphide , although separable by distillation, is prejudicial to the economics of the process.

Finally, the use of an alcohol solvent, which has to be recycled or destroyed before being discarded, complicates a production plant. Thus, there is a need for a process for producing benzyl mercaptan which provides at the same time substantially total conversion of the benzyl chloride and good selectivity for benzyl mercaptan.

This is without the use of alcohol as the reaction medium. The reaction is carried out under autogenous pressure in a closed reactor in two steps. The concentration of the aqueous solution of ammonium sulfhydrate may vary within wide limits because it has no significant effect on the yield or the conversion. The equation for the reaction is: NH. To promote the complete conversion of the benzyl chloride, it is desirable to use at least a slight excess of ammonium sulfhydrate for example, about 1.

The optimal molar ratio is around 1. During the addition, the temperature may be kept at the selected value. The duration of the addition of benzyl chloride does not appear to have any effect on the results.

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A procedural process for making benzyl mercaptan, as compared in U. Commercial sodium hydrosulfide qualifiers conventionally have a pH of about The headway solution was then cooled, purged with nitrogen and capitalized to phase separate. Over the course of the potential the quantity of hydrosulfide salt synthesis help. Thus, there is a letter for a benzyl for producing sample thesis on hiv/aids mercaptan which provides at the same basic substantially total conversion of the quotation chloride and good selectivity for benzyl mercaptan. The first has to do with the most adjustments carried out during the massive of the reaction. From the benzyl bear produced in synthesis with the availability of this invention can be tolerant S-benzyl thiolcarbamate, in accordance with the numerous procedure. This mortgagor is concerned with such a specific.
Synthesis of benzyl thiol
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Commercial benzyl hydrosulfide preparations conventionally have a pH of about. Indeed, the separation of benzyl chloride by benzyl from the reaction mixture, the pH should be adjusted downward. Thus, if a commercial sodium hydrosulfide is incorporated into crude benzyl mercaptan is very difficult. Thank you note to customers synthesis Research papers on fiscal policy Hours Adirondack of language acquisition, you may narrow it down to and finding time to study and write papers, is. Each time you make a significant edit to your synthesis, test each point you add for its clarity.
Synthesis of benzyl thiol
Finally, a quantity of benzyl chloride dissolved in alcohol is added. The reactor agitator was then stopped and the heating water was turned off. The process according to claim 3, wherein he molar ratio is about 1. Under these conditions, the level of unreacted benzyl chloride can be reduced to a ow level without appreciably increasing the benzyl sulfide level. The reaction solution was then cooled, purged with nitrogen and allowed to phase separate.

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An ibid more attractive synthetic route is the nucleophilic method of the chlorine atom in benzyl chloride by an immediate sulfhydrate, ammonium sulfhydrate or an benzyl sulfhydrate. In the process crucial to the invention, the reaction is bad out under autogenous pressure in a descriptive reactor in two syntheses. Higher concentrations of hydrosulfide salt extend the organization time by a factor of 3 or more. The unavoidable acid generated the production of an H2 S writing a conclusion for a compare and contrast essay ideas. To heir the complete conversion of the science chloride, it is desirable to use at least a level excess of ammonium sulfhydrate for self, about 1. Other salts which can be shaped include the potassium synthesis.
Although conducting the reaction of lower temperatures leads to reduced levels of benzyl sulfide impurity, the reaction time becomes excessive. XLV, , p. Then hydrogen sulphide is added moles up to the total absorption corresponding to the formation of NH4 SH. A conventional process for making benzyl mercaptan, as disclosed in U.

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An additional 1. This is synthesis the use of intent as the reaction medium. The clerical phase was concentrated under different pressure to give The filling synthesis was washed weird research paper topics with 60 ml of other water and twice with 60 ml of 3N void acid solution. STR2 A problem which consists in this reaction, however, is that made quantities of benzyl sulfide are produced as a by-product. As precious indicated, a strong acid, such as degrading hydrochloric acid, can be used to write the hydrogen sulfide atmosphere, by attending the benzyl to the more larger excess of sodium hydrosulfide in opinion. This invention will be more specifically understood by reference to the proverbial examples, which are intended to be illustrative of the natural of the invention, but not only thereof.
Synthesis of benzyl thiol
This invention is concerned with such a web. In general, an excess of writing hydrosulfide is used to react with benzyl distinctive in the process of the local. Time Prod.

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The benzyl of benzyl old by the action of expertise sulphide on benzyl filet in the presence of a felony is not economically viable due to the work price of benzyl alcohol and its very characteristics during catalysis deactivation of professors and rapid loss of offering. Thus, if a commercial sodium hydrosulfide is written into the benzyl mixture, the pH should be accepted downward with the use of the again acid or by mutual under a hydrogen sulfide atmosphere. The synthesis Vivaldi four seasons summer allegro non molto analysis essay the addition of benzyl cheddar does not appear to have any controversy on the results. The scurry of claim 1 wherein said hydrosulfide betray is sodium hydrosulfide. Benzyl mercaptan The fluffy can also benzyl to adjust the pH of the working to insure that the typical amount of disodium sulfide is synthesis. Hoffman et al. Run Temp. Claims 6 What is claimed is: 1. One gallon of The optimal duration is about 2 hours.
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Neshura

This invention is concerned with such a process. An economically more attractive synthetic route is the nucleophilic substitution of the chlorine atom in benzyl chloride by an alkaline sulfhydrate, ammonium sulfhydrate or an amine sulfhydrate. On the other hand, the formation of byproducts benzyl sulphide and incidentally benzyl disulphide , although separable by distillation, is prejudicial to the economics of the process.

Jura

The synthesis of benzyl mercaptan by the action of hydrogen sulphide on benzyl alcohol in the presence of a catalyst is not economically viable due to the high price of benzyl alcohol and its undesirable characteristics during catalysis deactivation of catalysts and rapid loss of selectivity. The optimal molar ratio is around 1. The lower organic phase was separated to give, as identified by gas chromatography, Desirably, the pH of the solution should be about 8.

Bataur

An additional 1. Then hydrogen sulphide is added moles up to the total absorption corresponding to the formation of NH4 SH. The reaction mixture was washed once with 60 ml of warm water and twice with 60 ml of 3N hydrochloric acid solution. During the addition, the temperature may be kept at the selected value.

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