Gleichgewicht von Milchsäure und Milchsäure‐anhydrid in Handelsmilchsäure

Abstract

,,Sehr storend ist die regelmassig stattfindende Anliydrdhildung, die umso starker ist. je konzentrirrtw die Sdure und je langer die Lagerung ist. In starker Verdunnung L . B. heim Gebraiich in den Lederfabrilen, zerfallt das Anhydrid wieder, sodass demnacli der SBuregehdt nur sckieinbar verringert war. 1;iine 50-proe. SBure sol1 hochstens 1,5% bis 1,8%, eine 80-proz. Saure 37+49/0 Anhgdrid enthalten, nicht aber l5"/, w k es bisw d e n bpi lang dauerndem Einkochen oder h i sehr langer Lngerung der hochprozentigen Saure vorlrommt ."Dass der Gehalt an anhydrisierter Saure in frisch hcrgestellter Handelsmilchsaure relativ gering ist, beweisen uns folgende Angaben aus der Technik6).

Lactic Acid Condensation Polymers

“…These three components occur in various proportions, the extreme limits bein pure water and completely polymerized lactic acid, I. Lactide, If, has the same ultimate composition as completely polymerized lactic acid, but appears to occur only in traces (3 6,18,13,16,17) in equilibrium mixtures of monomeric lactic acid, water, and polylactic acid. The ease (1, 6, $6, 30) with which lactide, 11, is hydrolyzed to lactyl lactic acid is of interest in this connection.…”

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223 S = channel slope t = time U = mean velocity in z direction v = turbulent velocity component perpendicular to direction of w2 = mean square value of e, Y2 = mean square value of transverse spread of diffusing matter 2 = distance downstream from point a t which diffusing matter mean flow -is injected xo = scale of turbulence defined by Rdx e = kinematic eddy viscosity p = fluid density T = unit shear in fluid LITERATURE CITED (1) Dryden, H. L., IND. The present paper summarizes earlier information on polylactic acid, much of which (3, 6) has not been readily available and describes both batch and continuous methods for dehydrating or polymerizing lactic acid.

PREVIOUS INVESTIGATIONSAlthou h the reported findings o f previous workers are not in complete agreement, aqueous lactic acid solutions and dehydrated lactic acid appear to consist mainly of "free lactic acid:' (monomeric a-hydrox onic .acid), water, an^^^^^^ condensation or self-esterification products, such as lactyl lactic acid and lactyl lactyl lactic acid, 111:

HOCH(CHs)COOCH(CHs)COOCH(CHs)COOH

(111)These three components occur in various proportions, the extreme limits bein pure water and completely polymerized lactic acid, I. Lactide, If, has the same ultimate composition as completely polymerized lactic acid, but appears to occur only in traces (3 6,18,13,16,17) in equilibrium mixtures of monomeric lactic acid, water, and polylactic acid. ONDENSATION products or polymers of C lactic acid are important because: (a) They occur in all aqueous solutions of lactic acid containing approximately 18% lactic acid or more.

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Analysis of Lactic Acid-Lactate Ester Systems

“…N. BANK American Cyanamid Company, Calco Chemical Division, Bound Brook, N. J. BECAUSE the concentration of free sulfur trioxide in chlorosulfonic acid is of importance in some of the uses of this acid, it became necessary to develop a more precise method for its determination than that generally used, which involves a total acid value and a chloride value (3,3,5,6). This method is not sufficiently precise because it is necessary to determine the sulfur trioxide indirectly, and the factors involved are such that an error of 0.1% each in the acid value and the chloride value causes an error of 1.0% sulfur trioxide.…”