What Every Chemist Should Know about Patents (2019, ACS) - "Patents play an important role in the chemical enterprise, both as a means for protecting the fruits of research and development from unauthorized use by competitors and as a major component of the chemical literature."  The American Chemical Society has created this excellent guide about patents and the law. 

See also: UB LibGuide on Patents 

General Portals and Directories

Chemie.de Information Service - Commercial portal & search engine

Chemical Information Sources (CHEMINFO) - Chemical information links 

Electrochemistry Knowledge Base - by Dr. Zoltan Nagy; links to resources in Electrochemistry

Virtual Chemistry Center - Martindale's Reference Desk

Specific Portal and Directories 

Analytical

See also Spectra and Spectral Data Research Guide

• Chromatography Book Series (R. P. W. Scott)
• Molecular Expressions - Optics & Microscopy (Florida State Univ.) - Fantastic collection of images

Inorganic/Organometallic

See also A Guide to the Beilstein and Gmelin Handbooks Research Guide 

• Johnson Matthey Technology Review (formerly Platinum Metals Reviews until 2014) -This journal provides detailed properties and phase diagrams of platinum group metals and their alloys, metal catalysts, and related materials.

Materials/Polymer

See also Properties Data for Chemicals and Materials 

• The A to Z of Materials (Azom) - Searchable database by keyword, application, and property values
• Polymer Tradename Index (MatWeb)

Medicinal/Toxicology

See also Toxicology In-Depth Research Guide 

• BindingDB (Univ. of Maryland) -30,000 measured affinities to proteins for over 15,000 small molecule ligands
• BioCyc Database - Pathway/Genome Databases
• Chemical & Engineering News Safety Letters (ACS) - Hazardous reactions reported to C&E News
• Chemical Entities of Biological Interest (ChEBI) [EMBL-EBI] - Compiles information on small molecules from many Internet resources including IntEnz, KEGG Compound, PDBeChem, and ChEMBL.

Organic

See also A Guide to the Beilstein and Gmelin Handbooks Research Guide 

• Organic Chemistry Portal - includes NMR shift predictions (Reto Muller)
• Organic Syntheses Monograph Series - Wiley (requires free ChemDraw plug-in)

Physical

• Atomic Reference Data for Electronic Structure Calculations (NIST)
• Fundamental Physical Constants (NIST)

Compound & Reaction Databases

Chemical Structure Lookup Service (NCI CADD Group) - metasearch of over 27 million compounds in over 80 internet chemical databases

Chemical Thesaurus Reaction Chemistry Database (Meta-synthesis, Inc.) - Open access synthetic route information. Database can be downloaded.

NCI Open Database - 250,000+ compounds with 2-D & 3-D structures collected by the National Cancer Institute for anti-cancer testing.

Reciprocal Net (NSDL) - Database of 3-D molecular structures compiled by crystallographers

Wikipedia Chemical Structure Explorer 

Career Information

Chemical & Engineering News Chemjobs (ACS)

Naturejobs (Nature Magazine)

Science Careers (Science Magazine)

Woman-Related Sites in Science & Technology (Joan Korenman)

ACS Meeting Locator - Not limited to ACS sponsored meetings.

Conferences & Events (Chemistry) (Maintained by RSC)

Science Meetings and Events (Science Magazine)

ACS Chemistry Education Resources - from elementary school graduate education

The ChemCollective (Carnegie Mellon/NSDL) - Virtual labs and scenario-based learning

National Science Teachers Association (NSTA) Learning Center

Practical Chemistry (Nuffield Foundation/RSC) 

Principles of Chemical Science (MIT OpenCourseWare) - includes video lectures, lecture notes, and exams.

Science Education Games & Puzzles (Thomas Jefferson National Accelerator Facility)

​What's That Stuff (ACS) - Chemical composition of everyday items like Silly Putty and cheese whiz.

Books, Journals, Open Access

CAplus (Chemical Abstracts) Core Journal Coverage List 

Directory of Open Access Journals 

Directory of Open Access Repositories

Google Books 

HathiTrust 

RoMEO - Over 400 publisher copyright and self-archiving policies (SHERPA)

Dictionaries, Periodic Tables, & Aids

ACS Style Guide (Quick Guide) (Williams College)

IUPAC Compendium of Chemical Terminology - free version of classic book. 

Periodic Table of Comic Books (Holler & Selegue, Univ. of Kentucky)

Periodic Table of Elements (Theodore Gray) 

Periodic Table of Videos (Martyn Poliakoff, Univ. of Nottingham) 

Visual Elements (RSC) - Graphical interpretation of element.

Software

Data & Property Calculation Web sites (Univ. of Illinois at Chicago)

Estimation Program Interface (EPI) Suite (U.S. EPA) - Physical/chemical property and environmental fate estimation model calculations

Macs in Chemistry (Cambridge MedChem Consulting) 

OSRA: Optical Structure Recognition - converts graphical structures in electronic documents into SMILES notation.