Reviewer(s)’ comments to author: reviewer: 1 comments to the author in their manuscript, gambarotti et al. demonstrate the straightforward synthesis and isolation of zwitterionic alpha-omega amino acid building blocks starting from galactaric acid suitable for polycondensation reactions to derive hydroxylated polyamides. the key step is the formation of the lactone from the diacid form of galactaric acid – a bio-based component, a reaction that had already been described in the 1990s, as is also referenced in this paper. the novelty comes from the addition reaction with different small molecular weight diamines to derive, in a simple and efficient manner, the zwitterionic salt of the diacid-diamine conjugate. indeed, the use of so-called ah salts is a common strategy in industrial polyamide synthesis to ensure 1:1 ratio of the diamine and diacid monomers, an important requisite to derive high molecular weight polymers from polycondensation reactions. the authors provide detailed structural analysis by nmr that agrees with similar structures from literature. an important advantage of the presented work is the isolation of the desired product without the requirement of additional activation or protection chemistry due to the immediate formation of the zwitterion. while the authors can demonstrate that the molecular weights derived from their approach are higher (for 4a) than for the previously reported aa/bb approach, the final molecular weights are still rather low (4 kda, dp 10-13). reaction times for the polymerizations are at 12-18 hrs, for similar reactions in literature reaction times of up to 7 days or more are found. from the experimental section, it seems that the reaction was stopped once the reaction mixture became homogeneous. however, as a stepwise polymerization process, the polycondensation could still continue leading to further increase in molecular weights with longer reaction times. this should at least be discussed, or potentially explored experimentally. thank you for the comment. in the experiment with ethylenediamine the system was heterogeneous, whereas in the other cases the mixture turned homogeneous. more experiments have been performed in order to investigate the polymerization showing that in the case of ethylenediamine (heterogeneous system), after 48 hours actually the dp was slightly higher (14.7 vs 13.2) but some degradation products seemed to be present as shown in the h nmr reported below