What class of chemical compounds do plants produce during photosynthesis?

carbon dioxide

Carbon dioxide is a by-product of the oxidation of the resulting products of the photosynthesis. In the day, the plant produces sugars by means of photosynthesis (with oxygen as a by-product). The different gas release between day and night isn't widely appreciated by people who refer to the rain-forests as 'the lungs of the planet'. OK, they (and the potted thing on your windowsill) release oxygen through the day. But they release carbon dioxide at night and this more or less balances out.

chlorophyll

Here is a very helpful site.

http://www.pinetum.org/Lovett/photosynthesis.htm

Sugars. Namely sucrose, glactose, and others. Typically five carbon or six carbon rings which form the building blocks of cellulose, which most of the plant is composed of, aside from water. Oxygen is also produced, and carbon dioxide is consumed.