If you like us, please share us on social media.
The latest UCD Hyperlibrary newsletter is now complete, check it out.

ChemWiki: The Dynamic Chemistry E-textbook > Organic Chemistry > Reactions > Reaction Fundamentals > Pushing Arrows

Copyright (c) 2006-2014 MindTouch Inc.

This file and accompanying files are licensed under the MindTouch Master Subscription Agreement (MSA).

At any time, you shall not, directly or indirectly: (i) sublicense, resell, rent, lease, distribute, market, commercialize or otherwise transfer rights or usage to: (a) the Software, (b) any modified version or derivative work of the Software created by you or for you, or (c) MindTouch Open Source (which includes all non-supported versions of MindTouch-developed software), for any purpose including timesharing or service bureau purposes; (ii) remove or alter any copyright, trademark or proprietary notice in the Software; (iii) transfer, use or export the Software in violation of any applicable laws or regulations of any government or governmental agency; (iv) use or run on any of your hardware, or have deployed for use, any production version of MindTouch Open Source; (v) use any of the Support Services, Error corrections, Updates or Upgrades, for the MindTouch Open Source software or for any Server for which Support Services are not then purchased as provided hereunder; or (vi) reverse engineer, decompile or modify any encrypted or encoded portion of the Software.

A complete copy of the MSA is available at http://www.mindtouch.com/msa

Pushing Arrows

Table of Contents

In organic chemistry, it is important to understand the concept of electron flow. In polar reaction mechanisms, such as the nucleophilic substitution reactions of haloalkanes, electron flow will be designated by arrows indicating the movement of electrons from electron rich regions to electron poor regions.


In considering this concept, we must look at the two types of arrows provided in the mechanisms shown below. The curved arrows indicate the movement of electrons. The first type of arrow, shown in pink, originates from the electron pair of the nucleophile and extends to the electrophilic carbon of the haloalkane. This type of movement does not indicate that electrons leave the nucleophile; rather, it means that electrons become shared between the nucleophile and the electrophilic atom.

The second type of curved arrow, also shown in pink, originates from the R-X bond and extends to the halogen. This indicates cleavage of the bond, whereby the electron pair becomes separated from R, the electrophilic carbon, and ends up on the halogen atom.

Haloalkanes 02.bmp

While we are using the concept of nucleophilic substitution mechanisms to explain electron flow, it is very important to understand that this concept will be applied in nearly all the mechanisms you learn throughout your course of study. The simplest way to think about this in any mechanism you learn is that electrons will be pushed from an electron rich species or site to an electron poor species or site, and the direction of the curved arrow will indicate this.

ContributorsEdit section

  • Rachael Curtis

Last modified
10:14, 1 Jan 2015



(not set)
(not set)

Creative Commons License Unless otherwise noted, content in the UC Davis ChemWiki is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. Permissions beyond the scope of this license may be available at copyright@ucdavis.edu. Questions and concerns can be directed toward Prof. Delmar Larsen (dlarsen@ucdavis.edu), Founder and Director. Terms of Use