Dzvinchuk, I. B. et al. published their research in Ukrainskii Khimicheskii Zhurnal (Russian Edition) in 1999 | CAS: 1877-75-4

2-(4-Methoxyphenoxy)acetic acid (cas: 1877-75-4) belongs to ethers. Of all the functional groups, ethers are the least reactive ones. Ether bonds are quite stable towards bases, oxidizing agents and reducing agents. But on the other hand, ethers undergo cleavage by reaction with acids. Ethers are good solvents partly because they are not very reactive. Most ethers can be cleaved, however, by hydrobromic acid (HBr) to give alkyl bromides or by hydroiodic acid (HI) to give alkyl iodides.Synthetic Route of C9H10O4

Recyclization to 1-pyrazol-3-yl-1H-benzimidazoles in the reaction of 2-phenacyl-1H-benzimidazole hydrazone with carboxylic acids was written by Dzvinchuk, I. B.;Vypirailenko, A. V.;Lozinskii, M. O.. And the article was included in Ukrainskii Khimicheskii Zhurnal (Russian Edition) in 1999.Synthetic Route of C9H10O4 This article mentions the following:

Reaction of 2-phenacyl-1H-benzimidazole hydrazone (I) with RCOOH (R = H, Me, PhCH2, 2-thienylmethyl, aryloxymethyl) at 150-200° gave 1-pyrazol-3-yl-1H-benzimidazoles (II). In the experiment, the researchers used many compounds, for example, 2-(4-Methoxyphenoxy)acetic acid (cas: 1877-75-4Synthetic Route of C9H10O4).

2-(4-Methoxyphenoxy)acetic acid (cas: 1877-75-4) belongs to ethers. Of all the functional groups, ethers are the least reactive ones. Ether bonds are quite stable towards bases, oxidizing agents and reducing agents. But on the other hand, ethers undergo cleavage by reaction with acids. Ethers are good solvents partly because they are not very reactive. Most ethers can be cleaved, however, by hydrobromic acid (HBr) to give alkyl bromides or by hydroiodic acid (HI) to give alkyl iodides.Synthetic Route of C9H10O4

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem