Links

Reaction Info

Info on reactions (inc. named items), electron pushing, acid/base catalysis, natural pdt. syntheses

• Acronyms (Hans Reich's Collection - DOC)
• Carbonyl Chemistry (Hans Reich's Collection - DOC)
• Electron Pushing/Drawing Mechanisms (Hans Reich's Collection - DOC)
• Total Syntheses Indexed by Named Reactions (Hans Reich's Collection - DOC): set of ~700 total synthesis schemes indexed by named reactions
• Named Reagents (Hans Reich's Collection - DOC)
• Named Rules and Effects (Hans Reich's Collection - DOC)
• Organic Reactions
• Organic Syntheses
• Protecting Groups-Organic Chemistry Portal
• Terms used in Physical Organic Chemistry

• Reaction Topics

  • Acidity and Basicity (Prof. William Reusch, Michigan State University)
  • Combinatorial Chemistry Review
  • Combinatorial Chemistry (at Science Direct)
  • Flow Chemistry-Organic Chemistry Portal
  • Green Chemistry
  • Green Chemistry-Organic Chemistry Portal
  • Microwave Syntheses-Organic Chemistry
  • Multicomponent Reactions-Organic Chemistry
  • Organoboron Chemistry
  • Organocatalysis-Organic Chemistry
  • Organometallic Chemistry (Hans Reich's Collection - DOC)
  • Pericyclic Reactions (Hans Reich's Collection - DOC)
  • Photochemistry (Prof. William Reusch, Michigan State University)
  • Reduction and Oxidation (Hans Reich's Collection - DOC)
  • Sonochemistry-Organic Chemistry

• Other Sites on Named Reactions

  • Name Reaction.com (Toronto, by Endri Gjiri)
  • Named Reactions-Organic Chemistry Portal (by Doug Taber)
  • Organic Reactions (Wikipedia)
  • SynArchive.com (by Daniel Beaudoin)
  • Monomerchem, Inc. (by Marcus Brackeen)
  • "ReactionFlash™ App" (developed by Elsevier and Prof.Erick M.Carreira, ETH-Zürich): over 1000 named reactions, their mechanisms and examples published in peer-reviewed literature
  • ReactionGuessr: a guess named reaction game, developed by Vincent Le Fouler

• Lists of Total Syntheses (Reaction Schemes are included)

  • Natural Product Syntheses (Hans Reich's Collection - DOC)
  • Totally Synthetic Blog (by Docherty/Taber)
  • SynArchive
  • Total Synthesis of Natural Products Dojo
  • Prof. Dirk Trauner (New York University) group's Total syntheses problem sets
  • "Synthesis Club Roadmap Problems" by German Cancer Research Center
  • "Synthesis Workshop" by Dr. Matthew Horwitz: an open access video podcast, including four complementary modules - Total Synthesis, Named Reactions, Research Spotlights, and Culture of Chemistry
  • University of Utah, Dept of Chemistry Synthesis Club: provides students a platform to hone their presentation skills and get exposure to relevant synthetic topics outside the focus of their research project(s)

Chemical Data

Info on pKa values, nucleophile/electrophiles, A-values, solvents, physical constants, etc.

• A-Values (Hans Reich's Collection - DOC)
• Bond Energies and Bond Dissociation Energies (Prof. William Reusch, Michigan State University)
• Bond Dissociation Energies (Prof. Armen Zakarian, University of California Santa Barbara)
• Bond Dissociation Energy Estimator by the National Renewable Energy Laboratory (NREL)
• Electronegativities of Elements-Periodic Table (Hans Reich's Collection - DOC)
• Organoboron Chemistry
• pKa Values (Water, DMSO, gas phase) (Hans Reich's Collection - DOC)
• Properties of Common Organic Compounds (Steven Murov)

• Nucleophile/Electrophile Reactivity

  • Database of Nucleophilicities and Electrophilicities
  • Mayr's Reactivity Scales Poster 2020
  • Mayr's Reactivity Scales Poster 2016
  • Reactivity Scales for Organocatalytic Reactions Poster

• Solvents

  • Solvent Properties Table
  • Solvent Miscibility Table
  • Solvent Strength Translator: predict a solvent system composition that would give similar eluotropic strength
  • Solvent Strength Calculation (see pages 8-15)
  • Green Chromatography Solvent Selection Tables (Green Chem., 2012,14, 3020; Supplementary Data)
  • See the DOC Green Chemistry Page

• Periodic Tables

  • Web Elements (interactive)
  • PTable (interactive)
  • PTable (PDF)
  • IUPAC
  • IUPAC (PDF)
  • American Elements (interactive)
  • Chemicool (interactive)
  • Elements Database (interactive)
  • Chemiplus (interactive)
  • Resources on Periodic Table (Steven Murov)
• Photophysical Properties of Photosensitizers and Quenchers (Steven Murov)
• Physical Constants
• Physical Constants wall chart (NIST)
• SI Units
• Nomograph (Boiling point vs Pressure, Aldrich)
• Data Conversion
• Frequency - Wavelength - Energy Converter (Prof. William Reusch, Michigan State University)
• Chemistry Data Tables (Wired Chemist)

Spectroscopy Resources

Info on: NMR (1H, 13C, 19F 31P, 11B, 77Se), IR, UV, MS spectroscopy and links to spectra databases

• General

  • Spectroscopy (Prof. William Reusch, Michigan State University)
  • Spectroscopy Lectures-Nowick (UCI)

• General NMR

  • NMR Spectroscopy (Hans Reich's Collection - DOC)
  • NMR Spectroscopy (Prof. William Reusch, Michigan State University)
  • NMR Supplemental NMR Topics (Prof. William Reusch, Michigan State University)
  • The Basics of NMR-Hornak (Rochester Institute of Technology)
  • NMR Dictionary
  • NMR Multiplet Guide-Nowick (UCI)
  • Basics of NMR (University of Dundee)
  • Dr. Glenn Facey (University of Ottawa) NMR blogs

• NMR Data

  • ¹H NMR Shifts (Hans Reich's Collection - DOC)
  • ¹³C NMR Shifts (Hans Reich's Collection - DOC)
  • Coupling: J_(H–H) (Hans Reich's Collection - DOC)
  • Coupling: J_(C–C) and J_(C–H) (Hans Reich's Collection - DOC)
  • NMR Solvents (Hans Reich's Collection - DOC)
  • Cambridge Isotope’s Solvent Table
  • NMR Trace Impurities (Organometallics, 2010)
  • NMR Trace Impurities (J. Org. Chem., 1997)

• Multinuclear NMR Data

  • ¹⁹F NMR Shift (Hans Reich's Collection - DOC)
  • ¹⁹F NMR Coupling Constant (Hans Reich's Collection - DOC)
  • ¹⁹F NMR Spectral Database by Prof. David Vicic (Lehigh University)
  • ³¹P NMR Shift (Hans Reich's Collection - DOC)
  • ³¹P NMR Coupling Constant (Hans Reich's Collection - DOC)
  • ¹¹B
  • ⁷⁷Se NMR Shift (Hans Reich's Collection - DOC)
  • NMR Periodic Table

• Mass Spectroscopy

  • MS Spectroscopy (Prof. William Reusch, Michigan State University)
  • Exact Masses & Isotope Abundance Ratios and Calculators (Prof. William Reusch, Michigan State University)

• UV Spectroscopy

  • UV Spectroscopy (Prof. William Reusch, Michigan State University)

• IR Spectroscopy

  • IR Spectroscopy (Prof. William Reusch, Michigan State University)
  • IR Problems (Prof. William Reusch, Michigan State University)
  • IR Problems/Training (Colby College)

• Databases of Spectra

  • Spectral Database for Organic Compounds (SDBS)
  • NMRShiftDB (database of spectra and tools to predict spectra)
  • Polymer Science Learning Center Spectral Database
  • ChemSpider

• Problems

  • Interactive exercises of solving structures from NMR spectra
  • NMRShiftDB Problem of the Month, Archive
  • NMR Spectral Problems (UCLA)
  • Spectral Zoo Problems
  • 20 Problems (CU Boulder)
  • 64 Problems (Notre Dame)
  • Spectroscopy Exams-Nowick (UCI)
  • NMR Problems - Rainer Haeßner (www.nmr.tips): Sets of NMR problems and with interactive walk-through solutions. An overview of all problems can be viewed on this page

Organic Compound Info

Info on naming organic compounds, functional groups, assigning R/S. and organic compound types

• Nomenclature

  • General Information (Hans Reich's Collection - DOC)
  • Functional Groups Summary (Hans Reich's Collection - DOC)
  • Named Reagents (Hans Reich's Collection - DOC)
  • Reactive Intermediates (Hans Reich's Collection - DOC)
  • Acronyms (Hans Reich's Collection - DOC)
  • Nitrogen Containing Functional Groups Summary (Hans Reich's Collection - DOC)
  • Abbreviations: Journal of Organic Chemistry
  • IUPAC (ACDLabs)
  • RSC IUPAC Rules (RSC, free registration required)
  • IUPAC Compendium of Chemical Terminology (the Gold Book)
  • IUPAC Glossary of Class Names of Organic Compounds and Reactive Intermediates 1995
  • Numbering of Ring Systems

• Stereochemistry

  • Chiral Configurations (Prof. William Reusch, Michigan State University)
  • IUPAC Rules for the Nomenclature of Organic Chemistry, Section E: Stereochemistry(1974)
  • Axial chirality-Wikipedia
  • Chirality and Odour Perception

• Organometallic Topics

  • Organolithium Reagents (Hans Reich's Collection - DOC)
  • Organometallic Chemistry General (Prof. William Reusch, Michigan State University)
  • Organometallic Hypertextbook

• Organic Compound Special Types

  • Heterocyclic Chemistry (Prof. William Reusch, Michigan State University)
  • Nitrogen Containing Functional Groups Summary (Hans Reich's Collection - DOC)
  • Pesticides
  • Polymers (Prof. William Reusch, Michigan State University)
  • Carbohydrates (Prof. William Reusch, Michigan State University)
  • Proteins and Amino Acids (Prof. William Reusch, Michigan State University)
  • Nucleic Acids (Prof. William Reusch, Michigan State University)
  • Steroids
  • Sweeteners
  • Aroma Compounds-Wikipedia

• Databases

  • CAS Source Index (CASSI) Search Tool
  • Beyond CASSI
  • ChEMBL (RSC): manually curated databases of bioactive molecules with drug-like properties (~6900 compounds, ~9800 bioactivities)
  • Chemical Abstract Service (CAS)
  • ChemSpider (RSC)
  • ChemSynthesis
  • eMolecules (suppliers)
  • OSIRIS Property Explorer
  • PubChem (NIH)
  • RCSB Protein Databank
  • Reaxys
  • Science of Synthesis
  • Unichem
  • WolframAlpha: Chemistry

• Sites on Some General Info on Organic Compounds

  • Compound Interest (infographics on various topics)
  • Disease Focused Posters-Jón Njarðarson (Arizona)
  • Top 200 Pharmaceuticals Posters-Jón Njarðarson (Arizona)
  • Molecules with Silly or Unusual Names
  • Molecules that Matter
  • Molecule of the Month

Safety Resources

Links to useful resources for safe operations of organic chemistry laboratories

• Dow Lab Safety Academy
• Lab Safety Institute
• OSHA Occupational Chemistry Database
• Prudent Practices in the Laboratory (Free download, PDF)
• UCLA: Health & Safety
• UC San Diego-Lab Safety Video Links
• Safety Data Sheet (SDS) lookup by ChemInfo: SDS quick lookup by brand, catalog number, or CAS number from Acros, Maybridge, Fisher, TCI, Fluorochem
• Safety Data Sheet (SDS) lookup by ChemicalSafety
• Lab Treatment of Waste Chemicals
• Stability of Diazo Compounds and Diazo Transfer Reagents

Chemical Societies and Portals

Links to chemical societies especially those that have a focus on or related to organic chemistry

• American Association for the Advancement of Science
• American Chemical Society
• American Chemical Society, Division of Organic Chemistry
• Canadian Society for Chemistry, Organic Division
• Chemical Institute of Canada
• International Isotope Society
• International Society of Heterocyclic Chemistry
• National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChe)
• North American Catalysis Society
• Royal Society of Chemistry-Organic Division
• The Society of Synthetic Organic Chemistry, Japan
• The World Association of Theoretical and Computational Chemists
• The American Association of Pharmaceutical Scientists

Literature Sources

Links to literature resources (i.e. lists of journals with an organic chemistry focus)

• ACS Organic Division's Links to Organic Journals
• Organic Reactions
• Organic Syntheses
• ACS Online Publications
• The Goodman's Group List-University of Cambridge
• Reference Resolver

Laboratory Techniques

Links to resources for doing various general laboratory procedures in organic chemistry labs

• Not Voodoo Organic Techniques/Information
• NOP General Techniques
• NOP all Experiments
• ChemSpider Synthetic Procedure Pages
• Organic Syntheses
• "The Schlenk Line Survival Guide" by Dr. Andryj Borys
• Reaction Setup and Safety Videos (University of Dundee)
• Working with Nitrogen Lines: the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland
• Titration of Organolithium: compiled by Emslie group (McMaster University), hosted by the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland
• Transfer of Chemicals Using Syringes: the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland
• Cooling Baths: compiled by the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland
• TLC Stains
• Solvent Degassing
• Solvent Degassing by Freeze-Pump-Thaw: the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland
• Gas Handling: the Waser group at EPFL, the Swiss Federal Institute of Technology in Lausanne, Switzerland

Useful Software

Links to software applications that are likely useful for a broad selection of organic chemists

• Chemical Drawing Programs

  • ChemBioDraw

  • ChemBioDraw Tutorial Videos by Pierre Morieux

    • Colorful ChemDraw Collections
    • ChemDraw Magic 4: How to REALLY use ChemDraw 17, Using Hotkeys
    • ChemDraw Magic Tricks: Quick Catalytic Cycles
    • ChemDraw Magic 3: Dendrimers, Delivered
    • ChemDraw Magic 2
    • ChemDraw Magic 1
    • All Videos by Pierre Morieux
  • ChemDoodle
  • MarvinSketch: Structure Drawing Software

• Computational Chemistry

  • AMSOL
  • Wavefunction: Spartan

• Chemical Inventory and/or Electronic Lab Notebook (ELN)

  • "Open Enventory": free, open-source chemical inventory & ELN

    • User Guides
    • Original Software by Dr. Felix Rudolphi
    • Modified Version by Dr. Khoi Van: Dr. Khoi Van added some extra functions as well as some modification for U.S.-based users. Used by Texas A&M University, labs at Baylor University, labs at MIT.
  • "Sciformation" by Dr. Felix Rudolphi: Paid software for ELN, Inventory, LIMS, with broader applications beyond chemistry
  • "LabCup": Paid software for Chemical Inventory and Laboratory Management

• Diagram Drawing Programs

  • Chemix: online editor for drawing science lab diagrams and school experiment apparatus.
  • Biorender: online editor for drawing science diagrams with a library of life science related icons.

• Others

  • Spaya.ai: A computational method for identifying the best synthetic route to a target compound.
  • Awesome Cheminformatics: A curated list of Cheminformatics software, resources, and libraries.
  • Awesome Python Chemistry: A curated list of Python frameworks, libraries, software and resources related to Chemistry
  • Cheminfo.org: variety of tools for cheminformatics, including but not limited to: SDS lookup, search by exact mass in Pubchem, Wikipedia Chemical view, etc.
  • Search by exact mass in Pubchem: Search Pubchem database for compounds using provided exact mass
  • Chemcalc.org: collection of mass calculators: molecular formula to exact mass; mass to prediction of molecular formula; proteins/polymer mass distributions analyses; Mass spec exercises
  • Peptide Calculator: Including hydrophobicity, net charge at different pH, isoelectric point, and the hydrophilicity ratio. By Bachem
  • Oligonucleotide Calculator: Provides the molecular weight of oligonucleotides with or without a DMT group and 2’-O modifications. By Bachem
  • MaxBridge
  • Schrödinger
  • Splotch.io: mobile app for organizing and annotating TLC data.
  • Vogel Scientific Software: CIARA and CALACO
  • Scientific Computing for Chemists with Python: JuPyteR Notebooks that pedagogically document Python usage for Chemistry.

Educational Resources

Links and resources for educators and students in teaching and learning organic chemistry

• Virtual Textbook of Organic Chemistry (Prof. William Reusch, Michigan State University)
• Acronyms (Hans Reich's Collection - DOC)
• ChemTube (3D Organic Chemistry Animations)
• Chemistry by Design-Jón Njarðarson (Arizona)
• Chemical Educational Xchange (by JCE)
• Chimie générale & organiqué-Gérard Dupuis
• Organic Chemistry InfoGraphics-Roman Valiulin
• Determining the product of Substitution or Elimination Reactions-Robert Grossman (Kentucky)
• Drawing Substitution and Elimination Products-Robert Grossman (Kentucky)
• Electron Pushing/Drawing Mechanisms (Hans Reich's Collection - DOC)
• Organic Education Resources (OrganicERs.org cCWCS)
• Polymer Education Guide
• R/S Chemistry-Master Assigning Absolute Stereochemistry-Neil Garg
• Stereochemistry Help-Robert Grossman (Kentucky)
• The Golden Rules of Organic Chemistry
• The Organic Coloring Book by Neil Garg
• The Adult Organic Coloring Book by Neil Garg
• Chemistry Hall
• QR Chem (presentation materials for instructors)-Neil Garg

• Lecture Notes

  • "Advanced Organic Chemistry", Prof. David Evans (Harvard): Chem 206 course notes
  • "Advanced Organic Chemistry", Eugene Kwan (Harvard): A set of reinterpretation of the Chem 206 course notes created by Professor David A. Evans
  • Heterocyclic Chemistry" (Prof. Phil Baran, The Scripps Research Institute): Also see Organic Chemistry Videos section for videos.
  • "NMR Spectroscopy" (Hans Reich's Collection - DOC): Chem 605 course
  • "Organic Synthesis", Prof. Andrew Myers (Harvard): Chemistry 115 Handouts, created as part of an advanced course on the synthesis of complex molecules
  • Open Source Lecture Notes-Bode Research Group (ETH-Zürich)
  • "Organometallics" (Prof. M. Christina White, University of Illinois)
  • "Organometallic Chemistry" (Hans Reich's Collection - DOC): Chem 842 course
  • Aliphatic C–H oxidation (Prof. M. Christina White, University of Illinois): graduate or advanced undergraduate level lecture.
  • 'Synthetic Design' (Prof. Dirk Trauner, New York University): course focuses on organic reactions, reaction mechanisms, and the strategic applications of reactions in organic synthesis
  • Sigman Group MLR Short Course (Prof. Matthew Sigman, University of Utah): video series describing the basic process the Sigman group uses to build multivariate linear regression models that describe chemical systems. This series is meant to be a starting point for chemists interested in using data science to study organic chemistry.

• Group Meeting Notes

  • Baran Group Meetings (The Scripps Research Institute)
  • MacMillan Group Meetings (Princeton University)
  • Richmond Sarpong Group Meetings (University of California Berkeley)
  • Scott Denmark Group Meetings (University of Illinois)
  • Ryan Shenvi Group Meetings (The Scripps Research Insititute)
  • Marty Burke (University of Illinois)
  • Brian Stoltz Group Meetings (California Institute of Technology)

• Questions and Problem Sets

  • Organic Chemistry Problems (Prof. Joseph J. Topczewski, University of Minnesota): example problems and answers for students at the introductory graduate student level or advanced undergraduate level
  • Organic Chemistry Practice Problems (Prof. William Reusch, Michigan State University): problems and answers in most undergraduate organic chemistry courses
  • "ReactionFlash™ App" (developed by Elsevier and Prof.Erick M.Carreira, ETH-Zürich): over 1000 named reactions, their mechanisms and examples published in peer-reviewed literature
  • Dave Evans Problem Set Generator: The late professor Dave Evans (Harvard University)'s chemistry problem sets
  • Fukuyama group problem set for graduate students
  • University of Utah, Dept of Chemistry Synthesis Club: seminar slides, problem sets, reagents/named reactions slides
  • RealOrganicChemistry Problem Sets: a collection of organic chemistry reactions taken from the scientific literature, with the intent of providing real-life practice problems for introductory organic chemistry students. Developed by Prof. Dennis D. Cao, Macalester College

• Tutorials

  • MolSSI Education Resources: Free online tutorial materials including Programming, Software Development, and Computational Molecular Science.
  • Nadia Laschuk tutorial videos: tutorials for beginner for ChemDraw, Origin, Mnova, Topspin
  • CGFigures (Dr. Joseph G. Manion): Blender tutorials for scientists trying to get started with 3D software to make better figures

Organic Chemistry Videos

Links to collections and individual (significant/historical) videos about organic chemistry-often lectures

• DOC Videos Page (NOS, historical, & Virtual Symposia)
• Eminent Organic Chemist Videos
• Chemistry Video-clip Library
• Heterocyclic Chemistry @Scripps Lectures 2019 by Prof. Phil Baran
• Organomettallics @Scripps Lectures 2019 by Prof. Keary Engle
• "Synthesis Workshop" by Dr. Matthew Horwitz: an open access video podcast, including four complementary modules - Total Synthesis, Named Reactions, Research Spotlights, and Culture of Chemistry
• Protein Data Bank Videos

Other Sites and Resources

Links on topics related to organic chemistry that do not fit in the other categories on this page

• Chemical (Academic) Genealogy Database
• Famous Organic Chemists
• Nobel Prizes in Chemistry on Nobelprize.org

• Accessibility, Diversity, Equity, and Inclusion

  • Diversify Chemistry: Highlighting the diverse community of chemists, aiming to help symposium organizers, award committees, search committees, etc. identify chemists who might diversify their pool.
  • Female Organic Chemists: Female Organic Chemists website and Female Organic Chemists in University Settings (FOCUS) database to highlight women in the field of organic chemistry. FOCUS database contains over 800 scientists representing over 35 countries
  • The Scoopula: A website founded to increase the accessibility of general advice, guidance, and resources for pursuing graduate school in chemistry

• Chemistry Portals

  • Chemistry 2000, Cambridge
  • Hans Reich's Organic Chemistry Info (Hans Reich's Collection - DOC)
  • Organic Chemistry Portal
  • Organic Chemistry Resources Worldwide
  • Organic Chemistry Links by the Mohr Group
  • Alfa Aesar's Organic Chemistry Resources

• MedChem/Pharma Links

  • ACS Division of Medicinal Chemistry (MEDI)
  • Biospace Pharmaceutical Company News
  • FiercePharma Pharmaceutical Company News
  • Mayo Clinic
  • Drug design online talks (University of Dundee)
  • NIH Entrez Search

• Research Group Indices

  • Organiclinks (Matt McIntosh's List of Organic Research Groups-Now hosted by the DOC)
  • ChemBiolinks by Jared Shaw
  • Stephen Chamberland's List of PUI Organic Research Groups
  • Peptidelinks by James Nowick-UC Irvine

• Other Resource Collections

  • Dan Lehnherr’s Chemistry Resources Summary
  • "Meta-List of Free Organic Chem Resources" (Prof. Alex Grenning, University of Florida)
  • Prof. Dirk Trauner group Resource page
  • Prof. Ryan Shenvi group Resource page
  • Prof. Richmond Sarpong group Resource page
  • Prof. Jérôme Waser group Useful Links page
  • Nessa Carson (@SuperScienceGrl) Study Organic Chemistry Online Collection: A list of resources where you can learn and practise organic chemistry online

• Internships and Fellowships

  • Interships and Fellowships by DOC

ACS Green Chemistry

Industrial Green Chemistry content, curated by the ACS Green Chemistry Institute Pharmaceutical Roundtable. This organization is dedicated to replace unsustainable chemical practices with those that increase the efficiency of chemical industry with respect to waste generation.

• Selecting Green Solvents
• Selecting Green Reagents
• Biocatalysis
• Green Medical Chemistry
• Process Mass Intensity
• Green Chemistry Innovation Scorecard Calculator
• General Green Chemistry resources

Evans Problem Sets

A generator of Organic Chemistry problems, with filters of difficulty and topic, that is sourced from the renowned problem sets of Professor David Evans.

• Evans problem generator

Virtual Organic Textbook

The Virtual Organic Textbook that was originally developed as a resource at Michigan State University and has since become an on-going curation project of the DOC webmasters. We welcome and encourage contributions to the open-source resource for Organic Chemistry education!

• Virtual Organic Textbook