Beckmann, De Pythag.
The ketoximes by the action of acetyl chloride undergo a peculiar inframolecular re-arrangement known as the Beckmann trans formation (E.
Beckmann, Ber., 1886, 1 9, p. 9 8 9; 188 7, 20, p. 2580), yielding as final products an acid-amide or anilide, thus: RC(:N OH)R'-RC(OH) :NR' ---> As regards the constitution of the oximes, two possibilities exist, namely >C: NOH, or > C' ?, and the first of these is presumably correct, since on alkylation and subsequent hydrolysis an alkyl hydroxylamine of the type NH 2 OR is obtained, and consequently it is to be presumed that in the alkylated oxime, the alkyl group is attached to oxygen, and the oxime itself therefore contains the hydroxyl group. It is to be noted that the oximes of aromatic aldehydes and of unsymmetrical aromatic ketones frequently exist in isomeric forms. This isomerism is explained by the HantzschWerner hypothesis (Ber., 1890, 23, p. II) in which the assumption is made that the three valencies of the nitrogen atom do not lie in the same plane.
The isomerism of the oximes of unsymmetrical ketones is explained in the same manner, and their configuration is determined by an application of the Beckmann transformation (see Ber., 1891, 24, p. 1 3); thus: R C R' - R C(OH): NR'-->R Conhr'(R' and OH, " syn ").
Acids convert it into the O-oxime (benz-syn-aldoxime) which melts at 125° C. When distilled under diminished pressure the 0-form reverts to the a-modification (see Beckmann, Ber., 1887, 20, p. 2766; 1889, 22, pp. 4 2 9, 5 1 3, 1531, 1588).
Wallach (Ann., 1900, 312, p. 171) has shown that the saturated cyclic ketones yield oximes which by an application of the Beckmann reaction are converted into isoximes, and these latter on hydrolysis with dilute mineral acids are transformed into acyclic amino-acids; thus from cyclohexanone, e-amidocaproic acid (e-leucine) may be obtained: CH2" C NOH C CH 2 CH 2 7: ?12?CH2 CH2 NH /CH2 CH2 C02H CH2', An ingenious application of the fact that oximes easily lose the elements of water and form nitriles was used by A.
Hantzsch (Ber., 1891, 24, p. 13) has made use of the Beckmann reaction, whereby they are converted into acid-amides.
On the addition of phenylhydrazine it gives a phenylhydrazone, and with hydroxylamine furnishes an oxime C6H5.CH3.C=N.OH melting at S9°C. This oxime undergoes a peculiar rearrangement when it is dissolved in ether and phosphorus pentachloride is added to the ethereal solution, the excess of ether distilled off and water added to the residue being converted into the isomeric substance acetanilide, C6H5NHCOCH3, a behaviour shown by many ketoximes and known as the Beckmann change (see Berichte, 1886, 19, p. 988).
Azoximes can also be produced from a-benzil dioxime by the "Beckmann" change.
JOHANN BECKMANN (1739-1811), German scientific author, was born on the 4th of June 1739 at Hoya in Hanover, where his father was postmaster and receiver of taxes.
This work entitles Beckmann to be regarded as the founder of scientific technology, a term which he was the first to use in 1772.
In 1772 Beckmann was elected a member of the Royal Society of Gottingen, and he contributed valuable scientific dissertations to its proceedings until 1783, when he withdrew from all further share in its work.
Other important works of Beckmann are Entwurf einer allgemeinen Technologie (1806); Anleitung zur Handelswissenschaft (1789); Vorbereitung zur Warenkunde (1795-1800); Beitrage zur Okonomie, Technologie, Polizeiand Kameralwissenschaft (1777-1791).
The latter readily undergo the " Beckmann " transformation on treatment with acid chlorides, yielding substituted acid amides, RR' C:NOH -8250; RC(NR') OH - R CO NHR' (see OxIMES, also A.
Cronthal, Die Stadt Wiirzburg im Bauernkriege (Wiirzburg, 1887); Heffner, Wiirzburg and seine Umgebungen (Wiirzburg, 1871); Beckmann, Fiihrer durch Wiirzburg (1906); and Hollander and Hessler, Malerisches aus Alt-Wiirzburg (Wiirzburg, 1898).
Beckmann obtained P4 molecules from the boiling-point of carbon bisulphide solutions, and Hertz arrived at the same conclusion from the lowering of the freezing-point in benzene solution; E.