L-Glutamine, L-alanyl-

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-03-10 to 1994-08-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes

Type of method:

capillary method

Remarks:

additionally: Differential Scanning Calorimetry (DSC) method

Key result

Decomposition:

yes

Decomp. temp.:

>= 458 K

Remarks on result:

not determinable

Remarks:

the substance decomposed before melting point was reached

While the test substance was heated it decomposed into a liquid and a gas. Both determined temperature ranges in which the decomposition of substance took place were nearly in conformity (DSC: 461 K to 483 K; Liquid bath: 458 K to 474 K). The blue coloration of pH-paper caused by the evolving gas supports the assumption, that NH3 was released in the above listed temperature range. This is a supplementary proof that the test substance decomposes.

Details of the capillaries and glass tube observations:

Up to 443 K: no reaction

443 K: weak alkaline reaction detected by pH paper

458 K: strong alkaline reaction detected by pH paper, beginning of decomposition

469 K: weak softening, strong coloration of pH paper

470 K: substance became slightly brownish, strong coloration of pH paper

471 K: substance became soft and brown, strong coloration of pH paper

472 K: substance became dark brown, very strong coloration of pH paper

473 K: A liquid phase was formed and foam as emerged by evolving gas. Then a part of foam moved upwards within the capillary, very strong coloration of pH paper

474 K: crackling noise in the glass tube, very strong coloration of pH paper

475-477 K: Colour of substance changed to dark brown - black, substance looked foam-like, coloration of pH paper changed from weak to very weak to none

478-479 K: foamy substance began to build a liquid, no coloration of pH paper

480 K: Substance became completely liquid, weak coloration of pH paper

Conclusions:

The test item decomposed before melting starting at 458 K (EU Method A.1, Capillary method and Differential Scanning Calorimetry method).

Description of key information

The substance decomposes before melting, starting at 458 K (ca. 185 °C) (EU Method A.1, Capillary method and Differential Scanning Calorimetry method).