Exhibit 5.1

Loeb & Loeb LLP   345   Park Avenue New York, NY  10154-1895

Direct Main Fax

212.407.4000 212.407.4000 212.407.4990

July 27, 2017

Atlantic Acquisition Corp.

1250 Broadway, 36^th Floor

New York, NY 10001

Ladies and Gentlemen:

Reference is made to the Registration Statement on Form S-1 (the “Registration Statement”) filed with the Securities and Exchange Commission by Atlantic Acquisition Corp., a Delaware corporation (the “Company”), under the Securities Act of 1933, as amended (the “Act”), covering an underwritten public offering of (i) 4,000,000 units (the “Units”), with each Unit consisting of one share of the Company’s common stock, par value $.0001 per share (the “Common Stock”), and one right to acquire one-tenth (1/10) of a share of Common Stock (the “Rights”), (ii) up to 600,000 Units (the “Over-Allotment Units”) which the underwriters will have a right to purchase from the Company to cover over-allotments, if any, (iii) an option (“Unit Purchase Option”) to purchase up to 250,000 Units (the “Purchase Option Units”) granted to Chardan Capital Markets, LLC, the representative of the underwriters (the “Representative”), (iv) all shares of Common Stock and all Rights issued as part of the Units, Over-Allotment Units and the Purchase Option Units, and (v) all shares of Common Stock issuable upon exercise of the Rights included in the Units, Over-Allotment Units and the Purchase Option Units.

We have examined such documents and considered such legal matters as we have deemed necessary and relevant as the basis for the opinion set forth below. With respect to such examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as reproduced or certified copies, and the authenticity of the originals of those latter documents. As to questions of fact material to this opinion, we have, to the extent deemed appropriate, relied upon certain representations of certain officers of the Company.

Based on the foregoing, we are of the opinion that:

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A limited liability partnership including professional corporations

Atlantic Acquisition Corp. July 27, 2017 Page 2

We are opining solely on (i) all applicable statutory provisions of Delaware corporate law, including the rules and regulations underlying those provisions, all applicable provisions of the Constitution of the State of Delaware and all applicable judicial and regulatory determinations, and (ii) with respect to the opinions expressed in paragraph (2) above, the laws of the State of New York.

In addition, the foregoing opinions are qualified to the extent that (a) enforceability may be limited by and be subject to general principles of equity, regardless of whether such enforceability is considered in a proceeding in equity or at law (including, without limitation, concepts of notice and materiality), and by bankruptcy, insolvency, reorganization, moratorium and other similar laws affecting creditors’ and debtors’ rights generally (including, without limitation, any state or federal law in respect of fraudulent transfers); and (b) no opinion is expressed herein as to compliance with or the effect of federal or state securities or blue sky laws.

We hereby consent to the use of this opinion as an exhibit to the Registration Statement, to the use of our name as your U.S. counsel and to all references made to us in the Registration Statement and in the prospectus forming a part thereof. In giving this consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Act, or the rules and regulations promulgated thereunder.

Very truly yours,

/s/ Loeb & Loeb LLP

Loeb & Loeb LLP