I require basic molecule like toluene, benzene acetic acid derivatives. CDN ,and sigma Aldrich sell these molecule in very small quantity at very high cost. My requirement  either source in bulk or technology to synthesis.

Dear Saikat, thanks for the references for synthesis.. About online source , I almost cover all possible source available online. their is no commercial supplier on kg scale.

You may contact this vendor in China to see whether they are willing to synthesize C13 labelled blocks for you http://www.chemexpress.com.cn/ . They synthesized a lot compounds for us.

 Hope it will be helpful

Regards

Usually  the Carbon 14 is used for labeling & tracing the path of the reaction. What is purpose of labeling 13 C which is about  1 % in the nature ? . Is it commercially available .Take these things in account.