optical chemical structure recognition from images
What way I could follow to achieve this?


Create a dataset with image-label pairs.
Create a classification model.


I don't think you will find any algorithm "out-of-the-box" for you to use.
You might have a look at some paper to see the kind of approaches they have.

I would recommend you look at these:


https://arxiv.org/ftp/arxiv/papers/1802/1802.04903.pdf which uses convolution neural nets and a heatmap as an attention mechanism. It even deals with noisy images.
https://web.stanford.edu/class/cs231a/prev_projects_2016/optical_recognition_of_chemical_structures.pdf which tries to identify hand-drawn structures. It uses a sort of edge detection algorithm for recreating the hand-drawn structures.