DE453577C - Process for the production of acetyl derivatives from amino compounds - Google Patents

Description

Process for the production of acetyl derivatives from amino compounds. It is known to use amines, such as. B. aniline, with the help of gaseous ketene in acetanilide convict. The reaction is either in the ethereal solution or directly in the Substance carried out because ketene also reacts with water and alcohol. It is it has become known that amines attach to ketene much more vigorously than Alcohols, however, it is not known that the difference between amines and hydroxyl-containing substances in the reactivity against ketene is so great, that in the practical acetylation no significant amount of hydroxyl is acetylated and that one even in hydroxyl-containing solvents and even can acetylate in aqueous solution. On the contrary, it is generally emphasized that Ketene immediately forms acetic acid with water and esters with alcohols, and one has on it even methods of determination for ketene were established. So you can also use amines in water acetylate or alcoholic solution with the help of ketene. It is very surprising that this preference for the nitrogen group also occurs when using acid salts of amines works or in aqueous alkaline solution. You can therefore with keten not only acetylate the easily acetylated aromatic aniline, but whole generally also the more sensitive aliphatic amines and furthermore bodies in general, which contain an amino group which is free or hidden by salt formation, such as amino alcohols, Aminophenols, aliphatic and aromatic aminocarboxylic acids and their salts, aminosulfonic acids and their salts, aminocarboxylic acid esters, their chlorohydrates, polypeptides, etc.

The procedure offers an essential one in various directions Innovation. In the previously common acetylation with acetic anhydride, acetyichloride etc. many connections are further changed, e.g. B. is when acting from excess acetic anhydride to glycocolla, the aceturic acid formed immediately further changed. In the case of aminocarboxylic acids, for example, acetylation is often a detour of their esters and subsequent saponification. During the acetylation with acetic anhydride usually delivers very impure products, one obtains according to the new processes directly pure bodies in excellent yield.

Another advantage of particular value is that the common acetylating agents, such as acetic anhydride or acetyl chloride, not only Amino groups, but also hydroxyl groups acetylate, while with ketene in aqueous Solution the process is so selective that one quite sharply restrict acetylation to the amino groups and so a new process for the partial acetylation of amino alcohols and aminophenols, in general of has polyvalent amino compounds.

Example i.

To acetylate glucosamine, 0.9 g of glucosamine chlorohydrate are dissolved in 6 ccm sodium hydroxide solution and diluted with a little water. In this solution one leads a continuous stream of gaseous excess ketene (represented by Passed over by acetone vapor over glowing platinum spirals) until the Congo acid reaction the solution, evaporated at low temperature in vacuo and separates the resulting Acetylglucosamine by pulling it out several times with absolute methyl alcohol Sodium chloride. 97 percent yield. Example

To acetylate aniline, i g is emulsified in 100 cc of water and directs a stream of gaseous ketene into the emulsion. After a few minutes it starts the deposition of the acetanilide formed. 75 percent yield.

Example 3.

For the acetylation of methyl aniline, 1 g is dissolved in 5 cc Alcohol and directs into the solution. continuous stream of gaseous ketene until the acidic reaction. When evaporating the solution in vacuo at low temperature methylacetaniline is obtained with a 75 percent yield. Example 4.

For the acetylation of p-aminophenol one treats a suspension of 49 p-aminophenol in 50 cc of 96 per cent alcohol with excess gaseous Ketene, with solution occurring after a short time. Obtained by evaporation in vacuo you get the p-acetaminophenol in 95 percent yield.

In an analogous manner, the o-aminophenol is the o-acetaminophenol to obtain. Example.

For the acetylation of glycocolla, the aqueous solution of the glycocolla is used or its sodium salt, allow excess gaseous ketene to act. At the Concentration in a vacuum in the first case, the aceturic acid crystallizes out directly Application of the sodium salt is used to isolate the aceturic acid with the residue Stripped of absolute alcohol. Instead of the sodium salt of glycolic glycol you can the aqueous solutions of the pyridine or brucine salt can also be used.

Example 6.

To acetylate leucine, 1 g of powdered leucine is dissolved in 90 ° ccm. hot water and treats the cooled solution with excess gaseous Keten. This is obtained by concentrating the solution at a low temperature in a vacuum formed acetylleucine.

Similarly, alanine, phenylalanine, tyrosine, serine, aspartic acid, glutamic acid, glycylglycine and histidine can be converted into their acetyl derivatives. Example 7.

For the acetylation of p-aminobenzoic acid, its aqueous solution is with Treated excess gaseous ketene and the acetaminobenzolecarboxylic acid by concentrating in vacuo isolated. 95 percent yield.

Example 8.

To acetylate sulfanilic acid, the aqueous solution of its sodium salt is treated with excess gaseous ketene, evaporated in vacuo and the p-acetaminosulfonic acid is isolated by extraction with absolute alcohol. Example g.

The aqueous solution is treated for the acetylation of glycollate with excess gaseous ketene, neutralized with the appropriate amount Caustic soda and potash and ether out. After evaporation of the essential solution the ethyl acetate is obtained.

Example io.

For the acetylation of methylamine, io ccm of an aqueous solution is ketenized 10 percent solution 4 hours. Concentration in vacuo gives a good yield the methylacetamide.

Claims (1)

PATENT CLAIMS: i. Process for obtaining acetyl derivatives from amino: compounds, such as aliphatic and aromatic nitrogen bases, amino alcohols, aliphatic and aromatic aminocarboxylic acids, aminocarboxylic acid esters, aminosulfonic acids, polypeptides, and alkyl derivatives of these substances, insofar as they still contain acetylable basic groups, by means of ketene, characterized in that a slight excess of gaseous ketene is allowed to act on these bodies in the presence of hydroxyl-containing substances or hydroxyl-containing solvents. a. Process according to Claim r, characterized in that substances which contain hydroxyl in addition to the acetylatable basic group are treated with gaseous ketene in the presence or absence of other hydroxyl-containing substances or solvents for the purpose of selective acetylation of the basic group.