Introduction:
Chromone (or 1,4-benzopyrone) is the derivative of benzopyran having a substituted keto group on the pyran ring. The derivatives of Chromone are collectively termed as Chromones. Most, although not all, Chromones are as well phenylpropanoids.
General Chemical reactions of Chromones:
Chromones vary marginally in their chemistry from Coumarins (benzopyran-2-ones) as the carbonyl group is now conjugated by the oxygen atom through the double bond of the heterocycle. This conjugation doesn't involve the benzene ring (figure shown below).
Fig: Chromone Conjugation
As a result, the Chromones are instead more basic and strong acids readily protonate the carbonyl oxygen atoms, making crystalline benzopyrilium salts. Once protonated, the molecule must be resistant to further electrophilic attack, however by fuming nitric acid and concentrated sulphuric acid at between 0°C and room temperature, Chromone provides the 6-nitro derivative (figure shown below). Chromone as well undergoes a Mannish-type reaction (figure shown below) with dimethylamine and formaldehyde (methanal) in hydrogen chloride and ethanol; here the product is 3-(N-N-dimethylaminomethyl) Chromone.
Fig: Reaction of Chromones
Comparatively hard nucleophiles, like Grignard reagents, might attack at the carbonyl carbon, while softer nucleophiles, example: hydroxide ion, join at C-2 by conjugative addition, and this might then cause ring opening (figure shown below).
Fig: Reactions of Chromones with Nucleophiles
Tutorsglobe: A way to secure high grade in your curriculum (Online Tutoring)
Expand your confidence, grow study skills and improve your grades.
Since 2009, Tutorsglobe has proactively helped millions of students to get better grades in school, college or university and score well in competitive tests with live, one-on-one online tutoring.
Using an advanced developed tutoring system providing little or no wait time, the students are connected on-demand with an expert at www.tutorsglobe.com. Students work one-on-one, in real-time with a tutor, communicating and studying using a virtual whiteboard technology. Scientific and mathematical notation, symbols, geometric figures, graphing and freehand drawing can be rendered quickly and easily in the advanced whiteboard.
Free to know our price and packages for online chemistry tutoring. Chat with us or submit request at [email protected]
Theory and lecture notes of Stock Market all along with the key concepts of the stock market, Government Purchases, Domestic Components of Aggregate Demand, homework help, assignment help. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Stock Market.
Cash Flows from Operating Activities, is the net outflow or inflow from trading operations, after tax payments (or receipts) and cash paid to meet financing costs.
We offer top-class Linear regression and Correlation Assignment Help from subject matter experts at viable prices to score A++ with quality solutions.
tutorsglobe.com description of a flower assignment help-homework help by online flower-a metamorphosed shoot tutors
tutorsglobe.com atp as high energy compound assignment help-homework help by online high energy compounds tutors
Purification–Recrystallisation of Benzoic Acid tutorial all along with the key concepts of Working example of purification, Experimental procedures, Buchner Funnel and Suction Flask, Dissolving Benzoic Acid
Alkene Synthesis from Alcohol tutorial all along with the key concepts of Preparation of Cyclohexene from Cyclohexanol, Dehydration, Laboratory display of Distillation
tutorsglobe.com hydrogen bonding assignment help-homework help by online intermolecular forces tutors
process costing - operating costing - cost accounting has been conventionally related with manufacturing companies.
tutorsglobe.com uses of bioinformatics assignment help-homework help by online bioinformatics tutors
Energy effects in Chemical reactions tutorial all along with the key concepts of Procedure of energy effects, Results of energy effects
Applications of the Benzofuran and Benzothiophene Ring tutorial all along with the key concepts of Amiodarone, Sertaconazole and Raloxifene
tutorsglobe.com thyroid gland and thyroxine assignment help-homework help by online co-ordination systems tutors
if the 1st phase, say r or a phase begins at slot no.1, the y or b phase should start at 1200/150 = 8 slots away that is, in slot (1 + 8 = ) 9, and the b or c phase should begin at (9 + 8 =) 17.
www.tutorsglobe.com offers the three oo principle homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
1933833
Questions Asked
3689
Tutors
1446450
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!