You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Synthesis and biological evaluation of thieno [2',3':4,5]pyrimido[1,2-b][1,2,4]triazines and thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidines as anti-inflammatory and analgesic agents. A new series of thieno[2',3':4,5]pyrimido[1,2-b][1,2,4]triazines and thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidines was synthesized. The newly synthesized compounds were evaluated for their anti-inflammatory and analgesic activity using diclofenac Na as a reference standard. Additionally, the ulcerogenic effects and acute toxicity (ALD50) values of the active compounds were also determined. In general, the thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidine derivatives exhibited better biological activities than the thieno[2',3':4,5]pyrimido[1,2-b][1,2,4]triazines. Collectively, the thienotriazolopyrimidine derivatives 9, 13 and 14a were proved to display distinctive anti-inflammatory activity at the acute and subacute models as well as good analgesic profile with a delayed onset of action. Moreover, they revealed good gastrointestinal safety profile and are well tolerated by experimental animals with high safety margin (ALD50 > 0.3 g/kg).
{"Chemical": ["thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidines", "diclofenac Na", "thieno [2\u0027,3\u0027:4,5]pyrimido[1,2-b][1,2,4]triazines", "thieno[2\u0027,3\u0027:4,5]pyrimido[1,2-b][1,2,4]triazines", "thieno[2,3-d][1,2,4]triazolo[1,5-a]pyrimidine", "thienotriazolopyrimidine"]}