The behaviour of 2-benzyl-4H-3,1-benzoxazin-4-one towards nitrogen nucleophiles namely, amino acids, aromatic amines, sodium azide, and secondary amines has been investigated. Also the reaction of 3-amino-2-benzylquinazolin-4(3H)-one and 2-[2-benzyl-4-oxoquinazolin-3(4H)-yl]acetohydrazide with carbon electrophiles has been discussed. As well as The novel synthesized compounds were evaluated as chemosensor for detecting formyl, carbonyl group and revealed high-selectivity and specificity to detect metals ions in water samples and, agricultural crops. Qualitative and quantitative assays indicated appreciable selectivity of novel compounds 13 and 15 as a chemo sensor for Optical detection of Hg 2 + and Cr 2 + respectively.Recently, detecting, and quantitative determination of cations especially toxic heavy metals such as Cd 2 + , Pd 2 + , Hg 2 + , Pb 2 + , Cr 3 + , etc. by using Colorimetric sensors is one of the scientists aim in the synthetic organic chemistry, environmental, water analysis, and medical laboratories. [1][2][3][4][5][6] Among these toxicants' heavy metals, Cr 3 + and Hg 2 + ions have gotten significant attention due to their widespread pollution. [7,8] In the last decade or so, many organic chemosensors were prepared for the detection of various ions. [9][10][11][12] Herein, we will synthesis colorimetric chemosensors showing high selectivity and specificity toward toxic heavy ions present in water samples and agricultural crops namely tomatoes and courgettes. Due to their biological significance and other properties, 4H-3,1benzoxazin-4-one derivatives are vital class of compounds. [13][14][15][16][17][18][19][20] On the other hand, dynamic 4H-3,1-benzoxazin-4-one derivatives bearing saturated aliphatic substituents at site 2 such as À CH 3 , [21] À C 3 H 7 , [22] À C 3 H 7 (iso), [23,24] CH 2 COCH 3 , [25] CH 2 CN, [26] CH 2 CH 2 COOH, [27] and NHPh [28] are interesting heterocyclic derivatives of this group of compounds. The electronically unsaturated character of these rings made it easily opening and detect of nucleophile easily, (so called chemo sensors). Compounds 1a so called metastable benzoxazin-one derivative easily prepared and due to the benzyl group at the site 2 rises the electronically unsaturated character of the oxazinone ring and increases its affinity towards nucleophile. This is the target, which are wanting to prove it in this study. The other aim of this article is valuation of the synthesized compound as a chemosensor for detecting toxic ion. Quinazolinones have involved notable interest in medicinal chemistry and organic chemistry, while limited reports were achieved for checking the sensor activity of quinazolinone derivatives. Ailin Yuan et al., synthesized novel quinazolinone compound as a fluorescence sensor for the ferric ion. [29] Quinazolinone based sensors for amine vapors and Cu 2 + ion [30] have been developed. As an extension of our awareness in synthesis of quinazolinone heterocyclic, we report that some quinazolin-4(3H)-ones can be used as a simple and efficient...
