Unsymmetrical aromatic ether diacids and absorbable polymers therefrom

A compound of formula I or a pharmaceutically acceptable salt thereof:

• [R′—(Y)p—O]q—Ar—[O—(X)r—R′]s I
• wherein:
• Ar is the aromatic portion of a diphenol;
• X and Y are independently selected from:
• —CH2COO—;
• —CH(CH3)COO—;
• —CH2CH2OCH2COO—;
• —CH2CH2CH2CH2CH2COO—;
• —(CH2)yCOO— where y is independently selected from 2-4 and 6-24;
• and
• —(CH2CH2O)zCH2COO— where z is independently selected from 2-24;
• provided that the groups represented by [R′—(Y)p—O]q— and —[O—(X)r—R′]s are different from one another;
• R′ is selected from H, benzyl, and C1-6 alkyl;
• p is selected from 1, 2, 3, 4, 5, and 6;
• q is selected from 1, 2, and 3;
• r is selected from 1, 2, 3, 4, 5, and 6;
• and
• s is selected from 1, 2, and 3.