Organic Chemistry
Topics

# How do you alkylate benzene?

Dec 1, 2015

You can do it via a Friedel-Crafts Alkylation, where you have an alkyl halide and a strong Lewis acid catalyst. Commonly we use ${\text{FeX}}_{3}$ where $\text{X}$ is often $\text{Cl}$ or $\text{Br}$.

The mechanism is as follows, and is very similar to Friedel-Crafts Acylation (and even draws parallels with the benzene halogenation reaction where you have ${\text{X}}_{2}$ in ${\text{FeX}}_{3}$...):

It is worth noting though that by adding an alkyl group onto benzene, you've added an activating group; that is, the alkyl group donates electrons to the ring, making it more nucleophilic, and thus more prone to reacting in this Friedel-Crafts Alkylation.

As a result, you have a pretty good chance for overalkylation if you don't add a controlled amount of catalyst and reactant.

##### Impact of this question
460 views around the world
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 6, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8518649935722351, "perplexity": 2602.369009036286}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585370496227.25/warc/CC-MAIN-20200329201741-20200329231741-00463.warc.gz"}