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8. Security - check for the yellow padlock on the Chromic Acid site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Chromic Acid, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Chromic Acid, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
Chromic acid refers to a collection of
chemical compound generated by the acidification of solutions containing
chromate and
dichromate anions or the dissolving of chromium trioxide in sulfuric acid.Chromic acid is prepared by treating a solution of 140 g of sodium dichromate dihydrate in 100 mL of water with 2 liters of sulfuric acid. Often the species are assigned the
chemical formula H2CrO4 and H2Cr2O7. The anhydride of these "chromic acids" is chromium trioxide, also called chromium(VI) oxide; industrially, this compound is sometimes sold as "chromic acid."
Regardless of its exact formula, chromic acid features chromium is in
oxidation state +6 (or VI), often referred to as hexavalent chromium. Chromium can exist in a number of oxidation states, hexavalent state is the highest. In its reactions chromic acid is reduced in
redox reactions to the 3+ ion, which has a distinctive blue green colour.
Uses
Chromic acid is an intermediate in chromium plating, and is also used in ceramic glazes, and colored glass. Because chromic acid solutions are powerful oxidizing agent they are used to clean
laboratory glassware. This application has declined due to environmental concerns. Furthermore the acid leaves residues that can interfere with certain applications, such as
NMR spectroscopy.
Reactions
Chromic acid is capable of oxidizing many kinds of
organic compounds and many variations on this reagent have been developed:
- Chromic acid in aqueous sulfuric acid and acetone is known as the Jones reagent, which will oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds.Freeman, F. "Chromic Acid" Encyclopedia of Reagents for Organic Synthesis (2001) John Wiley & Sons,
- Pyridinium chlorochromate is generated from chromium trioxide and pyridinium hydrochloride. This reagent converts primary alcohols to the aldehyde group (-CHO).
- Collins reagent is an adduct of chromium trioxide and pyridine used for diverse oxidations.
- Chromyl chloride, CrO2Cl2 is a well-defined molecular compound that is generated from chromic acid.
Illustrative transformations
- Oxidation of methylbenzenes to benzoic acids.
- Oxidative scission of indene to homophthalic acid.
- Oxidation of secondary alcohol to ketone (cyclooctanone) and nortricyclanone.
Use in qualitative organic analysis
In
organic chemistry, dilute
solutions of hexavalent chromium can be used to oxidize primary or secondary
alcohols to the corresponding aldehydes and ketones. Tertiary alcohol groups are unaffected. Because of the oxidation is signaled by a color change from orange to a blue-green, chromic acid is used as a qualitative analytical test for the presence of primary or secondary alcohols.
1
Alternative reagents
In oxidations of alcohols or aldehydes into carboxylic acids, chromic acid is one of several reagents, including several that are catalytic. For example nickel(II) salts catalyze oxidations by Sodium hypochlorite. Each oxidant offers advantages and disadvantages.
Safety
Hexavalent chromium compounds are toxic and carcinogenic. For this reason, chromic acid oxidation is not used on an industrial scale.
References
Alcohols from Carbonyl Compounds: Oxidation-Reduction and Organometallic Compounds (PDF)
External links
-
- National Pollutant Inventory - Chromium (III) compounds fact sheet
-
- IARC Monograph "Chromium and Chromium compounds"
Chromic acid refers to a collection of chemical compound generated by the acidification of solutions containing chromate and
dichromate anions or the dissolving of
chromium trioxide in
sulfuric acid.Chromic acid is prepared by treating a solution of 140 g of sodium dichromate dihydrate in 100 mL of
water with 2 liters of
sulfuric acid. Often the species are assigned the chemical formula H2CrO4 and H2Cr2O7. The anhydride of these "chromic acids" is chromium trioxide, also called chromium(VI) oxide; industrially, this compound is sometimes sold as "chromic acid."
Regardless of its exact formula, chromic acid features chromium is in
oxidation state +6 (or VI), often referred to as hexavalent chromium. Chromium can exist in a number of oxidation states, hexavalent state is the highest. In its reactions chromic acid is reduced in
redox reactions to the 3+ ion, which has a distinctive blue green colour.
Uses
Chromic acid is an intermediate in chromium plating, and is also used in ceramic glazes, and colored glass. Because chromic acid solutions are powerful
oxidizing agent they are used to clean laboratory glassware. This application has declined due to environmental concerns. Furthermore the acid leaves residues that can interfere with certain applications, such as NMR spectroscopy.
Reactions
Chromic acid is capable of oxidizing many kinds of
organic compounds and many variations on this reagent have been developed:
- Chromic acid in aqueous sulfuric acid and acetone is known as the Jones reagent, which will oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds.Freeman, F. "Chromic Acid" Encyclopedia of Reagents for Organic Synthesis (2001) John Wiley & Sons,
- Pyridinium chlorochromate is generated from chromium trioxide and pyridinium hydrochloride. This reagent converts primary alcohols to the aldehyde group (-CHO).
- Collins reagent is an adduct of chromium trioxide and pyridine used for diverse oxidations.
- Chromyl chloride, CrO2Cl2 is a well-defined molecular compound that is generated from chromic acid.
Illustrative transformations
- Oxidation of methylbenzenes to benzoic acids.
- Oxidative scission of indene to homophthalic acid.
- Oxidation of secondary alcohol to ketone (cyclooctanone) and nortricyclanone.
Use in qualitative organic analysis
In
organic chemistry, dilute
solutions of hexavalent chromium can be used to oxidize primary or secondary alcohols to the corresponding
aldehydes and ketones. Tertiary alcohol groups are unaffected. Because of the oxidation is signaled by a color change from orange to a blue-green, chromic acid is used as a qualitative analytical test for the presence of primary or secondary alcohols.
1
Alternative reagents
In oxidations of alcohols or aldehydes into carboxylic acids, chromic acid is one of several reagents, including several that are catalytic. For example nickel(II) salts catalyze oxidations by
Sodium hypochlorite. Each oxidant offers advantages and disadvantages.
Safety
Hexavalent chromium compounds are
toxic and carcinogenic. For this reason, chromic acid oxidation is not used on an industrial scale.
References
Alcohols from Carbonyl Compounds: Oxidation-Reduction and Organometallic Compounds (PDF)
External links
-
- National Pollutant Inventory - Chromium (III) compounds fact sheet
-
- IARC Monograph "Chromium and Chromium compounds"
Chromic Acid
CHROMIC ACID ANODISING . This process produces relatively thin coatings in the order of 2.5 microns which tend to be opaque or semi-opaque ...
Chromic acid - Wikipedia, the free encyclopedia
Chromic acid generally refers to a collection of compounds generated by the acidification of solutions containing chromate and dichromate anions or the dissolving of chromium ...
Definition: chromic acid from Online Medical Dictionary
The Online Medical Dictionary is a searchable dictionary of definitions from medicine, science and technology.
Elementis Chromium: Products and Applications/Chromic Acid
Chromic acid is used in the process of chrome plating and in the manufacture of wood preservatives.
Elementis Chromium: Products and Applications/Chromic Acid-CA ULTRA
Exceptional properties CA ULTRA™ is a specially designed chromic acid flake that has exceptional properties. It is virtually dust free, has a long, stable shelf life ...
Kurion UK - Chromic Acid Recycling for Chromic Acid Anodising
Specialist in Chromic Acid Regeneration for Chromic Acid Anodising. Chromic Acid Recycling saves disposal costs, supply costs, personnel time and safety due to reduced handling.
Prevention and Control of Exposure to Chromic Acid
4. Designating areas and installations that may be contaminated by chromic acid. Non-essential personnel should be excluded and warning signs similar to this must be displayed in ...
Prevention of Exposure and control of chromic acid mist
Prevention of Exposure and Control of Chromic Acid Mist Prevention of Exposure and control of chromic acid mist
NIOSH Publication Number 73-11021: Criteria for a Recommended Standard ...
NIOSH Criteria Documents Criteria for a Recommended Standard: Occupational Exposure to Chromic Acid. 1973 DHHS (NIOSH) Publication No. 73-11021
chromic acid - definition of chromic acid by the Free Online ...
Definition of chromic acid in the Online Dictionary. Meaning of chromic acid. Pronunciation of chromic acid. Translations of chromic acid. chromic acid synonyms, chromic acid ...
