Structural

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

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:

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:

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.

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:

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.

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.

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:

• 10-19: IUPAC recommended names and formulae. 10 is used for the recommended name or formula, such as "water", "H₂O", higher numbers are used for alternate spellings, such as "sulphur" for "sulfur", "aluminium" for "aluminum".
• 20-59: Other systematic names and accepted common names, e.g. "cyclohexa-1,3,5-triene" for benzene, "oxidane" for water.
• 60-79: Common names and synonymes, e.g. "guaranine" for caffeine.
• 80-100: Silly names, constructed common names, and intentionally overcomplicated or erroneously constructed systematic names, e.g. "dihydrogen monoxide" for "water".

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.

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;

and vice versa:

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:

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:

• butan-1-ol (n-butanol)
• butan-2-ol (sec-butanol)
• 2-methylpropan-1-ol (isobutanol)
• 2-methylpropan-2-ol (tert-butanol)

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:

• alkanes (e.g. ethane, C₂H₆)
• alkenes (e.g. propene, C₃H₆)
• alkynes (e.g. butyne, C₄H₆)
• cycloalkanes (e.g. cyclohexane, C₆H₁₂)
• simple acyclic alcohols (e.g. ethanol, C₂H₅OH)
• simple acyclic aldehydes (e.g. propanal, C₂H₅CHO)
• simple acyclic carboxylic acids (e.g. methanoic acid, HCOOH)
• nitroalkanes (e.g. nitropentane, C₅H₁₁NO₂)
• alkanethiols (e.g. ethanethiol, C₂H₅SH)
• alkanamines (e.g. propanamine, C₃H₇NH₂)
• alkanones (e.g. butanone, C₄H₈O)

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