Getting Structural

Click here to get Structural from the Mac App Store.

Structural Quickstart Guide

When you first open Structural, you should be looking at this:

The Structural main calculator window.

The first field is titled "Formula", and is for searching by and displaying chemical formulae.

The next field is "Name", and is used for searching by and displaying the names of chemical compounds.

The third field is named "Mass", and displays the calculated molar mass of the compound; based on the formula.

The most basic operation is entering a formula and having Structural calculate the molar mass of the compound it describes:

Formula Search

The formula "H2O" has been entered into the calculator's "Formula" field; yielding the name "water", as well as the molar mass 18.0150 u.

If the compound described by the formula is found in the internal application database of compounds, this search will yield one or more names; the preferred one of which is displayed in the combo box titled "Name". If several names are found, these can be accessed using the drop down menu, accessed using the arrow on the right-hand side of the field.

Conversely, the name field can also be used to search for compounds:

Name Search

The name "oxidane" has been entered into the "Name" field, yielding the formula "H2O", as well as the same molar mass as previously.

The search for "oxidane" (the IUPAC systematic name for water) yields the exact same result as searching for water would.

Even if a search by formula does not yield any results, the calculator will still calculate the molar mass of the formula:

Searches without results

The formula "CuSO4" is not found in the database, but it's molar mass is still calculated to 159.6020 u.

Using the Compound Database

When using Structural you may find that various compounds you often look up are not included in the database that ships with the application. Using the Compound Database, these can be added for lookup by name. The compound database is accessed through the "Window" menu.

Compound Database

A typical view of the internal database at the first run of Structural. The information for water has been expanded.

For uniqueness, the database is organized by a SMILES representation of the compound, which expands into lists of names and formulae.

The "Add" button is context sensitive, and pressing it when a compound is selected directly or nothing is selected at all, will bring up a dialog to add a new compound:

Adding a Compound

The SMILES entry sheet.

To add a compound, simply type in a SMILES string and press "Add".

Once the compound has been added, navigate into it to find the Names and Formulae lists. Selecting either of these and pressing Add, or accessing it from the "Edit" menu, will bring up a data entry sheet.

Adding a data item to a compound

The data entry sheet

If you simply wish to add a formula, type it in and it will be added at the default priority (60). The priority decides in what order names and formulae will be considered for display in the calculator window during lookup; with the lower numbers being displayed first.

If you wish, however, you can supply a custom priority value when defining the formula.

Adding a data item with priority

The priority number is added in parentheses after the formula

To set the priority, add parentheses after the formula, separated by as single space, containing a number between 0 and 100. In general, the priorities in Structural Team supplied repositories work like this:

To delete any item from the database, simply press the "Remove" button in the toolbar, or access it from the "Edit" menu. A dialog will pop up confirming the deletion.

Removing a data item

This dialog can be suppressed using the checkbox, or by accessing it through the alternate menu item, using the option key.

Warning: When deleting a compound, all associated names and formulae will also be deleted. Use caution!

The Add Item command is available using Command-+; and the Remove Item command is available using Command-Backspace; or, to delete without confirmation, Command-Option-Backspace.

Using Structural for stoichiometry

When a formula has been found, the "Amount" and "Weight" fields can be used to perform simple stoichiometric calculations. Entering the desired amount (in moles) of the formula will yield the weight;

Amount Calculation

After finding "NaCl"; "sodium chloride" (common table salt), an amount of 2 moles has been entered into the "Amount" field; yielding the weight of salt that will contain the desired amount.

and vice versa:

Weight Calculation

After finding "H2SO4"; "sulfuric acid", the measured weight has been entered into the "Weight" field, yielding the amount of the compound (in moles).

Procedurally generated names and formulae

Structural only ships with a modest database of some of the most commonly encountered compounds in basic inorganic chemical analysis as well as the basic chemical elements, but in addition to this it comes with a highly useful tool for most uses in basic organic chemistry: A procedural namer of some of the more commonly encountered homologous series:

Homologous series namer

While the members of the homologous series of alkanes is not found in the database; the calculator can still find its members, both by name and formula; such as for instance "C18H38", "octadecane".

The procedural namer only provides the "headliner" of any given group of structural isomers; and it is possible, and indeed likely, that the specific compound searched for does not yield the most precise name possible: The procedural name yielded by a search for "C4H9OH" will always be "butanol"; while the actual compound might more properly be any one of:

Attention must be paid to this point.

Put differently; Structural in this case arrives at the conclusion that it is a butanol, but does not make any attempts as to determining which butanol. Additionally; if the chemical formula is ambiguous, as is the case with "C6H12", the calculator might give multiple results; if the result of the search is counter-intuitive, be sure to access the drop-down menu for the "Name" field.

The currently supported (as of Structural 5.0.0) series are:

Structural 5.0.0 supports a parent chain length of up to and including 30 carbon atoms for any of these series.