E. ZMMET REID.
124
Addition in one of the carbonyl groups would best account for all the properties of the substance. While it is to be expected that water would split off from a compound containing a carbon atom united with two hydroxyls, our knowledge of the behavior of such a group in the neighborhood of other radicals is limited and a hydrate of thc .,.i-sulfonate such as indicated is not impossible. ,!.ddition appears to be represented in many chemical reactions. M1un1 elo'.\'v,
Cl,\Y
[ C O N T R I B I X I O S 1'ROW THE CHEMICAL LABORATORY OF JOHNS
HOPKINS UNIVERSITY.
THE IDENTIFICATION OF ACIDS. I3Y
E
EhfMET RBIU
liecnbed September 21, 1916
Progress in the investigation of natural products and in the analysis of artificial mixtures depends greatly on the possibility of preparing crystalline derivatives of the substances under investigation. We have satisfactory crystalline derivatives of aldehydes and of alcohols in the phenylurethanes and a- and P-naphthylurethanes, and of aldehydes in the phenylhydrazones and substituted phenylhydrazones. As organic acids occur in natural products in great variety and have been produced synthetically in immense numbers, their positive identification is of the utmost importance. Usually the amides, anilides and ptoluides are relied upon for the identification of acids, but, in some cases, these are difficult to prepare. It is desirable to have several series of derivatives so that if one fails in a particular case, another may be available. In important cases, in order to avoid the possibility of error, it is often necessary to prepare several different derivatives. Hence, a new series of crystalline derivatives, which are readily made from acids, may be of use. p-Nitrobenzyl bromide was prepared by Wachendorf' in 1877 by heating p-nitrotoluene and bromine in a sealed tube. He found that it reacted readily with sodiiim acetate to give the acetate m. p. 7 8 '. Now a derivative of acetic acid, which is formed readily from sodium acetate, crystallizes well, is not too soluble in alcohol, and melts sharply a t a conveniently high temperature, is very desirable as a means of isolating and identifying acetic acid. It seems remarkable that advantage has not been taken of this observation. The idencification of organic substances was not so much an object in Wachendorf's time, and his work Seems to have been overlooked. His statements about the ready formation of p-nitrobenzyl acetate suggested the present work. I t was thought that other p-nitrobenzyr esters might likewise be formed readity and might have convenient propertie2.CH3C,HIS(_)?, rn. 8g O , o-Toluate, o-C€€:CRH1CC)?.CH?Cs"(-)2,m. 90 7 O ; e-Nitrobenzoate, O - ~ O ~ C ~ H I O O L . - C € € ? C Gm. H ~ INI O I ~ 8,O ; o-Chlorobenzoate, o-ClC,H )2.CH2CaH4NOz,m. 106 Anthranilate, o-lit-12C,,HfC( 12.CHCoH+?jOL, m. 205 ', p-Bromobenzoate, p-RrCi,HICOs.CHzChHINOz,m. 139 j O ; 2,1-ninitrobetizoate. 2,4- 1O?)?CbH3CC)3.CH2C6H~~02, m. 1 4 2 . 0 ~ ; Phenylpropiolate, CBH,C CCCt2.CH~CbH4N02, m. 83 ; Thiocyanate, CS§.C€i?CJ&SO?, m. 8 j ', oxalate [.C(I?.CE€?CGII,S(~~~~, ni. 204' Xalonate, C I I ~ ( C ( I ~ . C H ~ C ~ , €m. ~ I S85.5 O ~O ), ~ , 'l'artrate, ( .IFOCHCc).CH~CI,IIINOL.j3, m. 163O Citrate, C3H,0-'CC1: CF12C~H&O?)?, m. 1 0 2 O. j
I
HAL. m I ( , m ,
31 D
[CO!iTRIBL?TIO?r FROM THE
LABORATORY OF FOOD CONTROL, BUREAUOF DsPARThlENT OF' LkGRICL7,TURE
CHEMISTRY,
]
THE IDENTIFICATION AND ESTIMATION OF LACTIC ACID IN BIOLOGICAL PRODUCTS. FIRST PAPERnl BY I K. PIILLPZA N D I i E. PALMBR. Received Octoher 2Z. i 9 l G
It is very obvious that thcrc is riecd for a method by which the identification of lactic acid and its estimation quantitatively can be actomplished. The fact that no ialt? of lactic acid insoluble in water have been discovered is, perhaps, the chief cause of the absence of such a method. This paper records some of the results obtained in the search for such a method, studying, in particular, the solubility of various salts and derivatives of lactic acid in organic solvents for the purpose of determining lactic acid in biological products whether natural or fermented. Trvine? resolved racemic lactic acid into its optically active components by means of the difference in solubility of their morphine salts in 1 Read at the 20th annual meeting of t h e Association of American Dairy, Food and Drug Otlicials, Detroit, Michiqm, Btigust 5-11, 1916 Published by permission of the
T I I I I I < ~ J ('henz CUC 89,
C)jj
(1906)
